The VeeCU

ArchiveBot · May 23, 2021, 5:00am

The VeeCU

Posted: Tue Mar 23, 2021 1:06 pm

by WesRagle

Hi Guys,

Retirement is supposed to be the time you do all those things you always wanted to do but just didn’t have the time while you were working. I’ve been retired for over three years now and I’m chipping away at the list. I wanted to build a Onex from the day it was introduced, check. The wife and I always wanted to get a travel trailer and visit the state parks, in work. And, I always wanted to work an engineering project outside the corporate environment, just for the sheer fun of it.

Well, it’s time to start on #3. The project will be an Engine Control Unit for my Onex. I am serious about the product but now that I have no title, no company, and no reputation to uphold, I can poke fun at myself. While I’m at it I’ll poke some fun at corporate America and all of characters that play a part.

Enter the first character, Bud. Bud’s a BD (Business Development) guy. Ref. (“https://www.urbandictionary.com/define.php?term=BD%20guy”). Bud is responsible for the title of this thread. He caught wind of what I was doing and immediately called a brain storming session to name the product.

The second character is Harold. I met Harold right out of school. Harold is the prototypical insecure engineer. He obsesses over every single detail. He wears dark rim glasses and the right ear piece is held on with adhesive tape. Harold comes complete with pocket protector and lives in constant fear of making a mistake. One more thing, Harold’s personal hygiene is somewhat lacking. Harold is a hardware guy. Last time I saw Harold he was walking in circles muttering something about load dumps, slew rates, electromagnetic radiation, and input signal conditioning. I’ll leave him alone for now. He’ll calm down eventually.

I’ll play a small part myself. I enjoy the software more than hardware. Like Harold I’m a bit of a social invalid. And…, I don’t have a very good filter between my brain and my mouth. That’s caused me grief my entire life, especially with the Suits.

Oh yes, the Suits. The Suits are an exceedingly odd group of folks, not like the rest of us. A Suit is likely to have their very own bathroom. I’m not sure why they want to live with their flatulence but it seems to be a status symbol. One things for sure, Suits have no sense of humor. You have to be very careful with these guys, they hold the purse strings. If a Suit ever approaches you with an “idea they’ve had”, even if it is a hopelessly and obviously flawed idea, don’t say a word. If you have to say something just say “Wow”. Freeze, stare off into space as if awe struck by a truly original thought. After a few moments ask for some time to think about it. Now, you need to train for this situation, just like pushing the nose over on a loss of power, the response needs to be automatic. If you’re lucky that will be the end of it. If not there are multiple full back positions. For those I charge a consulting fee.

Project details to follow.

Wes

Re: The VeeCU

Posted: Tue Mar 23, 2021 5:12 pm

by WesRagle

Just a reminder, I know this is not an economically viable project. This is therapy for me. All in good fun.

All I have is a text editor, no word processing software, I probably need to fix that.

So, here is a first cut at a top level document. If you think the verbiage sounds a bit like marketing fluff you’re right. Top level documents always start off that way. It’s an attempt to capture the intent of a product. From an engineering standpoint the top level document provides a place to record some basic system characteristics that can later be fleshed out into full blown requirements. If anybody sees a problem with the content let me know and I’ll fix it.

VeeCU Top Level Document Rev 0.01

Introduction:
The VeeCU is a microprocessor based Engine Control Unit designed specifically for air cooled Volkswagen engines that have been converted for aircraft use. The VeeCU is not designed to replace the engine’s existing induction and ignition systems but rather it is designed to augments those systems. The VeeCU provides all of the the benefits of port fuel injection and electronic ignition while retaining the existing manual systems as a proven backup.

In addition to the benefits of a traditional port fuel injection system the VeeCU allows the installer to trim each injector individually eliminating the fuel imbalance common to many VW conversions. The electronic ignition works in conjunction with fuel injection and provides optimum spark advance for rock solid idle and maximum fuel economy while cruising lean of peak.

The VeeCU’s compact size and rugged design allow it to be installed in the engine compartment thus minimizing wiring clutter in the cockpit.

Inputs:

Secondary Ignition Module Output (Front Cylinders)
Scaling 0 Hz = 0 RPM, 60 Hz = 3600 RPM
Range 0 - 5000 RPM

Secondary Ignition Module Output (Rear Cylinders)
Scaling 0 Hz = 0 RPM, 60 Hz = 3600 RPM
Range 0 - 5000 RPM

Primary Ignition (P-Lead)
Scaling 0 Hz = 0 RPM, 60 Hz = 3600 RPM
Range 0 - 5000 RPM

Manifold Air Pressure
Scaling TBD Volts = 20 Kpa, TBD Volts = 110 Kpa
Range 20 - 110 Kpa

Inlet Air Temperatre
Scaling TBD Volts = -40 Deg. C., TBD Volts = 70 Deg. C.
Range -40 - 70 Deg. C.

Mixture Control
Scaling TBD Angular Deg. CCW = -50 Pcnt., TBD Angular Deg. CW = +50 Pcnt.
Range -50 - +50 Pcnt

Communication Port
ARINC 825 data bus @ 1 Meg bit per second

Outputs:
Secondary Ignition Coil Input (Front Cylinders)
Secondary Ignition Coil Input (Rear Cylinders)
Four (4) High Impedance Injector drives.
Fuel Flow output. Open Collector output most likely simulating a Red Cube.
ARINC 825 data bus @ 1 Meg bit per second

Dimentions:
TBD

Weight:
TBD

Pinout:
TBD

Environmental:
In accordance with D0160X …

Re: The VeeCU

Posted: Fri Apr 16, 2021 1:18 am

by WesRagle

Hi Guys,

Some progress on the ECU.

The CPU is up and running with a small Real Time Kernel.

The four pulsed input channels have been implemented using one of the 32 bit timers. The edge on which the timer capture happens is programmable, so right now I’m just using a spare timer to drive the inputs for both front and rear coil secondary inputs. One captures on the rising edge and the other on the falling edge. Frequency and pulse width measurement is made to one micro-Sec.

The internal AtoD is a 12 bit SAR type with with 18 possible inputs. By the time I allocated all the pins needed for coil drivers, injector drivers, etc., there were 11 pins left for use as analog inputs. Right now I am measuring 11 external pins and two internal signals, core CPU Temp, and internal reference voltage. The AtoD is running in batch acquisition mode with all channels sampled and summed 8 times, shifted right 2 bits (so as to leave a rounding bit) and then dumped to memory via a DMA channel. The DMA terminal count ISR sums the new readings to four groups of readings. Each secondary ignition capture generates an interrupt which grabs the group with the most samples, copies it to a working group, and then zeros that group. Anyway, that gives me an average of the AtoD readings over the last two revolutions of the engine. I may change strategy during testing, but that’s the plan for now.

Two output bits have been allocated to verify/test timing.

The pics below shows timing bit #1, timing bit #2, and one edge of the “engine” timer. Timing bit #1 is toggled by the “idle” task. Any gap in toggling means either an ISR or a higher priority task is executing. In this pic Timing bit #2 is toggled at the beginning and end of the AtoD DMA terminal count ISR.

Looking at timing bit #1 you can see the AtoD DMA terminal count ISR, the Kernel timer tick ISR every mSec (along with the tasks triggered by the timer tick), and the input capture ISR (and the input capture task) generated by edge on trace #3. At present the input capture ISR just stores the captured value and signals the input capture task. In the future it will also output pulses for ignition and fuel injection. As you can see, the CPU is very lightly loaded at present.

The input capture task buffers the captured reading in a 30 reading circular buffer, calculates the period of the last revolution, the RPMS based on that period, and an RPM based on 0.3 second gate time (for display). This task also scales all of the AtoD readings to engineering units for use in calculating pulse width and phase for output.

I also bought the evaluation board for an ASIC (Application Specific Integrated Circuit) which targets 4 cylinder engine engine control. The ASIC provides a CAN bus driver, power for the CPU, two five volt outputs for sensor excitation, four injector drives, four pre-drives for the IGBTs that drive the ignition coils, and a lot of outputs that will go unused.

Up next is pulse generation followed by bringing up the Arinc 825 bus for communication with the control head.

Forever Forward,

Wes

Re: The VeeCU

Posted: Sat Apr 17, 2021 10:33 pm

by WesRagle

HI Guys,

I’ve been working on ignition pulses today. I want to feel comfortable using the secondary ignition for ground operations so I want to minimize current draw at lower engine speeds. So… the focus today has been timing AND “dwell”.

The following simulation sweeps the input from the secondary ignition module, the bottom trace (remember it will be adjusted to TDC) through a start sequence. The top trace is the wire that will be routed to the forward ignition coil and will trigger a spark on the falling edge of that signal. To test the control, below 500 RPM the spark is fired at TDC for 3 mSec. Above 500 RPM the dwell is adjusted to 25 mSec and advanced 90 Deg. (because it’s easy to look at). Exact advance and dwell will be calculated later.

The sequence:

Zoom at the transition from Start to Run (500 RPM).

Latency from ignition module input (the highest priority interrupt in the system) to spark generation during TDC firing.

Based on the following pic provided by Chris Madsen, 25 ms of dwell (on time) should be more than adequate to charge the coil. At idle (900 RPM) that amounts to a duty cycle of 0.375 which should cut the current consumption of the secondary ignition by at least half at idle. Using 5 Ohm coils should bring the secondary ignition current down to between 2 and 2.5 amps total at idle.

Recent testing has shown that there is just over 1 micro second of jitter in interrupt latency due to short critical sections in the real time kernel. That amounts to 0.0216 angular degrees of uncertainty at 3600 RPM. Nothing to worry about.

Also, the CPU is so low power that the core temperature only increases 2 centigrade degrees over ambient while running.

Did I mention that my Wife bought a travel trailer? Off on another vacation.

Wes

Re: The VeeCU

Posted: Sun Apr 18, 2021 11:54 am

by pappas

I’m kind of excited about your project and your postings. Of course, the only thing I understood in all of these posts was, “My wife bought a travel trailer”.

Nevertheless, I would love to see this working, and in the fleet. Keep at it!

Re: The VeeCU

Posted: Sun Apr 18, 2021 3:32 pm

by WesRagle

Hi Lou,

Thanks. I’ll keep at it and see where it leads. After this upcoming trip I’ll clean up the ignition code and add the injection pulses. That will probably be about a week of testing and study. Then I’ll bring up the communication bus.

You probably noticed me talking about the “Real Time Kernel”. The neat thing about having a kernel is that you can have multiple tasks (sub-programs) running on the same CPU with the highest priority program (that has something to do) running at any particular time. I mention this because the communication bus (CAN bus) can be initialized in “loop back” mode. In loop back mode the CAN transceiver receives what it transmits. In that mode I can insert a task that mimics the control head and perfect the communication protocol before I actually have to start wiring things together. The longer I can keep the project confined to a single CPU the faster I can make progress.

Anyway, it really is great fun and very inexpensive compared to building an airplane. The CPU board I’m using to breadboard the proof of concept cost a whopping $15.

My wife works jigsaw puzzles and I do this

Wes

Re: The VeeCU

Posted: Sun Apr 18, 2021 9:43 pm

by GordonTurner

Maybe we should talk some more about the jigsaw puzzles. I’m on the same apparently sink8ng ship as Lou…

Cheers, Gordon

Re: The VeeCU

Posted: Mon Apr 19, 2021 12:42 am

by WesRagle

Hi Gordon,

The VeeCU will intercept the ignition pulses coming from the secondary ignition module and use those pulses, in lieu of a crank sensor, to time fuel injection and the actual ignition pulses delivered to the secondary ignition coils. The secondary ignition will be adjusted to TDC (0 Deg. advance). The longer I can keep the project on the desk top the faster software development goes. So, simulation is key to rapid software development.

Since the MPU (Micro processing unit) has 16 timers on board, I am using one of the spare timers to simulate the pulses coming from the secondary ignition module. In it’s final form there will be input signal conditioning circuitry between the secondary ignition module and the MPU but I can ignore that for now.

Thinking about the end game, there will be two pulse streams coming from the secondary ignition module. One pulse per revolution on each stream with the pulses occurring 180 Deg. apart. Since the pulses are accepted on an edge and since the edge on which they are accepted is programmable, for the sake of simulation I can program the forward coil (from the secondary ignition module) to be accepted on a rising edge and the rear coil to be accepted on the falling edge. That way I can use the same square wave to drive both MPU secondary ignition inputs. Clear as mud?

Back to the previous image:

The bottom trace is the square wave simulating both pulses coming from the secondary ignition module with edges occurring at TDC. Looking at the top trace, those pulses will be driving the circuitry that actually fires the front ignition coil. While starting, that signal is driven low for 3 mSec right at TDC. The signal then goes back high to recharge the coil. Once the engine speed is up to 500 RPM ( 8.33 Hz) The ignition pulse is driven low 90 Deg. (1/4 of the signal period) before TDC. The signal is then driven high to recharge the coil ~25 mSec before it is fired again at 90 Deg. before TDC and so on.

Kinda hard to talk about but that’s what’s going on

Wes

Re: The VeeCU

Posted: Mon Apr 19, 2021 7:24 am

by GordonTurner

I’ll continue to monitor and input my my keen guidance to help you keep the project on track.

Re: The VeeCU

Posted: Mon Apr 19, 2021 10:37 am

by pappas

OK, great, give me a poke when you get to the part about how the inverse relationship between interest rates and bond prices in the secondary market begins to have an effect on the ignition firing sequence, and I may have some helpful input!

Re: The VeeCU

Posted: Mon Apr 19, 2021 11:54 am

by GordonTurner

Everything is connected.

Re: The VeeCU

Posted: Wed Apr 28, 2021 5:26 pm

by WesRagle

Hi Guys,

I’m back from vacation. While away I spent some time reading and trying to plot a way forward. My main reference for ECU specific information is this book:

A couple of sticking points I’m trying to figure out:

What I envision is a system that is implemented “According to Hoyle”. That is to say I don’t want a lot of unknowns floating around that get “baked in” to the VE table. So, I need fuel injectors that are perfectly characterized. In need dead time (as a function of voltage), the non-linear region of the flow curve (just as the injector opens), and the linear portion of the flow curve. I haven’t determined how to get that information. I’m afraid I will have to generate the information myself. That will take some time Anyway, if done correctly, changing injectors will only involve entering the correct information for the new injectors, not a lot of mucking around with the VE table.
I don’t have a dyno. I need to be able to vary load at a given RPM to build the VE table. The author points out, in a couple of places, that VE for a given RPM is linear with load. That implies that if I had a variable pitch prop I could make two (maybe three) runs at different pitch settings, stabilize at a given RPM, adjust Lambda to 1, record the fuel injected, and calculate VE at that RPM and load. I could then fill in any missing data using linear interpolation.

So, where do I get a variable pitch prop without breaking the bank? IVO? Has anyone used an IVO on a VW? Do you think an IVO would be OK for ground runs? The guys at IVO seem to think they are OK for VWs.

Thanks,

Wes

Re: The VeeCU

Posted: Sat May 01, 2021 9:50 pm

by WesRagle

Hey Guys,

I’ve been polishing up the ignition code. The finished code will have a “watchdog timer” that will reset the CPU within 5 mSec should it lose it’s way for some unknown reason. There will also be an R/C constant on one of the spare I/O pins to allow for a warm boot (no CRC of the code segment) if the watch dog triggers. I don’t think there is a good way to prevent a bad timing pulse if the watchdog triggers, but I want to ensure that there is no bad timing pulse when the system restarts. Before leaving the ignition code (for now) I simulated a watchdog event by tapping the reset button.

Each edge of the center trace represents a blade. The system is initialized to eEngineStopped state with the ignition coils de-energized. If both blades are seen within 2 seconds, the eEngineCranking state is entered and the ignition coils are energized. Once two blades are seen on the same channel and the RPM is greater than 650, eEngineRunning state is entered. During engine cranking, the coils are fired TDC. In this example during engine running the coils are fired 45 Deg advanced. As you can see, the system first fires on the third blade after reset. That occurred at TDC as the system spent one blade in the cranking state. Subsequent ignitions occurred at 45 Deg. advance. No bad pulses. Good enough for now. On to injection.

Wes

Re: The VeeCU

Posted: Sun May 02, 2021 12:48 pm

by Frankart

When I read your first post, i thought, that’s really cool. I wonder if I might have some knowledge that he could benefit from. I’ve used arduinos in my work to trigger bowling balls to get thrown by providing a ground to a an air cylinder.

After reading through the rest of the thread, you are clearly working at a level beyond what I have done or understand.

It sounds like a fun project. I will follow your updates and stay out of the way!

Re: The VeeCU

Posted: Sun May 02, 2021 3:18 pm

by WesRagle

Hi Frank ,<?>

Everybody has some nuggets to share.

Frankart wrote:After reading through the rest of the thread, you are clearly working at a level beyond what I have done or understand.

I spent my entire career working on projects of this type. It’s not beyond, above, or below, It’s just different. I have never written a Windows program and wouldn’t know an arduino if it walked up and smacked me in the face, but this type of programming I understand.

It’s that narrow slice of programming known as “Deeply embedded hard real time”. The processor and all the peripherals are your responsibility, reset to reset. BTW, “hard” in this context doesn’t mean difficult, it just means the deadlines are hard.

In the end I will have been entertained for countless hours and end up with a program that is only about 32 K Bytes in size. Contrast that with the size of a typical windows program. Like I said, it’s just different.

If you’re interested, the board I’m working with cost about $10 and the development environment is free. If you can flash an LED exactly once a second, you’re a hard real time programmer

Wes

Re: The VeeCU

Posted: Tue May 04, 2021 10:31 am

by WesRagle

Hi Guys,

I’ve pretty much beat ignition pulses to death. (Ref. https://sonexbuilders.net/viewtopic.php?f=66&t=6203#p47024).

The real focus of this project is fuel injection. But, since I intend to use my existing ignition system to time fuel injection I couldn’t resist adding ignition control.

The anticipated benefits of ignition control are:

Reduced current consumption during ground operations.

I intend to use 5 Ohm coils and control dwell to reduce current consumption at low RPM. At present the ignition pulse widths are controlled by two hard coded constants. MAX_DWELL = 25 mSec and MIN_BURN = 2 mSec. At low speeds MAX_DWELL dominates, at higher speeds MIN_BURN dominates. Again, the center trace is the simulated input, the top and bottom traces are the ignition pulses going to the forward and rear ignition coils (28 Deg. BTDC).

A pic of what works out to be 984 RPM with MAX_DWELL dominating.

A pic of what works out to be 3078 RPM with MIN_BURN dominating.

Hopefully I reduce the ignition current enough to cover the fuel pump and injector current during ground ops.

Smoother starts and Idle.

Initially I won’t/can’t fully map the ignition. So …, in that time honored engineering tradition of “Plagiarize what you can and invent the rest.”, I’m going to do what this guy did (sans ATDC timing):
Ref. page 4 of https://skycraft.ltd/docs/Leburg/EI10A_Electronic_Ignition_System.pdf.

Optimum spark advance during LOP operation.

Time will tell.

Anyway, we got some rain so it looks like the grass is actually going to grow this year. I need to take a break for ground keeper chores. My wife has scheduled another state park visit next week in her new travel trailer. I’ll get back to injection when we return.

Wes

Re: The VeeCU

Posted: Tue May 04, 2021 11:24 pm

by WesRagle

Guys,

I know I said I would go away for a while but … It’s hard to turn it off.

I’ve been thinking about what Brian said about ATDC firing during start/hand propping. And Brian, you’re right. All I’ll have to do is adjust the secondary ignition input to 10 Deg. ATDC and use the input the same way I am now during start and then adjust the arithmetic to remove the 10 Deg. once normal advance resumes. It will have the added benefit that the data used to calculate the delay until next spark during normal running is a little less stale. I’ve been staring at a scope and measuring pulses referenced to TDC for days now and just got a little case of tunnel vision.

Thanks,

Wes

Re: The VeeCU

Posted: Wed May 05, 2021 12:12 am

by Bryan Cotton

Attaboy Wes! Us ‘Y’ Bryans know our stuff too. I’ve also studied the Leburg unit and that is where I got the idea from. One of my future projects is a microprocessor based ignition for my 1981 Suzuki GN400. All the old CDI units are on borrowed time as the caps don’t last forever.

Re: The VeeCU

Posted: Wed May 05, 2021 12:35 am

by WesRagle

Sorry Bryan. I’m fried.

Mesley

Re: The VeeCU

Posted: Wed May 05, 2021 8:36 am

by Bryan Cotton

No worries! It was shocking as I’ve never seen my name misspelled before.

(That is a joke…)
Keep the cool stuff coming!

Re: The VeeCU

Posted: Mon May 17, 2021 2:36 pm

by WesRagle

HI Guys,

Back from the park and working on injection pulses.

Here is a shot of three of the injector pulses. One pulse has zero delay and 10 micro second duration. The second has 10 micro seconds of delay and 20 micro seconds of duration. The third has 30 micro seconds of delay and 30 micro seconds of duration. The forth was too hard to get to

The delay and duration are controllable in 10 micro second increments up to (delay + duration) = 65535. Setting the timer to 10 micro second increments allows 0.65535 seconds as the maximum pulse width. I can’t imagine every needing more than that. And, 10 micro second resolution on injector pulse width seems more than adequate. It makes for simple code so I’m calling that good enough.

It’s time for what new grads call re-factoring. It’s what we used to call clean up. I’ll start a new project in the development environment and bring the code over piece by piece improving/simplifying where ever possible.

Looking to the future, I’ve implemented the 3-D lookup routine for typical VE lookup. Not sure that is the way I’ll go but I’m ready if that’s what I decide. It’s interesting to see all the hoops folks jump through trying to get a good start (Ref.https://www.hptuners.com/help/vcm_editor_parameters_gm_eng_fuel_general.htm). We’ll see how that goes

It’s time to start considering signal conditioning. Can I really replace my ignition coils with optical couplers?? Hum…

EDIT: So, I couldn’t resist. I went to the shop and replaced one of the ignition coils with a 10K just for a test. When the DYNA-S fired the low end of the resistor went to 0.5 volts and then back all the way to bus voltage while “charging”. The DYNA-S hung in all the way to below 5 Volts at which point it just turned on (0.4 volts). So, looks like appropriately sized resistors and opto-couplers is a viable option for acquiring the secondary ignition pulse.

Forever Forward,

Wes

Re: The VeeCU

Posted: Wed May 19, 2021 5:47 am

by sonex1566

Hi Wes,
While you, Peter and a couple of others are chasing the perfectly smooth running engine down the electronic rabbit hole…I’ve gone down the opposite path using steam power instead. I’m almost finished machining up my own custom slide needle with two difference angles to cope with the different fuel demands of idle and high power settings. If nothing else it would make a good conversation to have over a beer whilst we work out who is crazier!. Good luck.

Re: The VeeCU

Posted: Wed May 19, 2021 11:29 am

by WesRagle

HI Richard,

“Crazier” is right. Anyone who builds an airplane in the garage/shop is certifiable to begin with.

That looks like a fun experiment. Me, I took the “Red Pill” and I’m way down the rabbit hole. If you’re able to balance fuel to the individual cylinders with that needle I’ll be out in a heart beat and begging for a copy

Wes

Re: The VeeCU

Posted: Sun Jun 20, 2021 12:15 am

by WesRagle

Hi Guys,

I’m down a rabbit hole in a rabbit hole. I going to attempt to “glue” four boards together to form the “Proof of Concept” unit for what will eventually be the VeeCU. In order to do that I need signal conditioning circuitry. So …, full speed ahead and damn the torpedoes. I’ve been trying to figure out how those folks I used to work with laid out PCBs.

I just sent off for my first attempt. What comes back may make for a good laugh. It costs about $60 total for a small two sided board (minimum qty. 5). BTW, the real deal will be laid out by a professional.

If there are any PCB designers and or EEs on the list, I would love your contact information so I could ask some questions

Now, back to the display board.

Forever Forward

Wes

Re: The VeeCU

Posted: Tue Jun 22, 2021 6:40 am

by sonex1566

Hi Wes,
I believe that there must be something wrong with me, but I was thinking about your problems today whilst stuck in traffic on my way to work this morning. Peter Henry put up his picture of his fuel manifold on the top of his injectors fitted to his inlet manifold and wondered how you were going to go fitting it inside your cowling. However, last year I wasted far too much time getting a mate’s Ducati Monster going after it had been sitting for years. But what I was thinking about was how Ducati got around supplying fuel to their injectors on their V-twin engine. They just used a banjo bolt in the top of each injector and used flexible fuel tubing to go from the pump and then from one injector to the other and then the fuel pressure regulator was tacked on the end where the unused fuel was returned directly back to the tank. I was wondering if that would be a simpler and more compact way of supplying fuel to your injectors. I’ll take the management role here and supervise you while you scratch your head and wonder how the hell you actually plumb it all together!

ArchiveBot · May 23, 2021, 5:00am

Re: The VeeCU

Posted: Tue Jun 22, 2021 10:06 am

by WesRagle

Hi Richard,

In the end analysis, I’ll have to keep the height of the injectors to a minimum. I don’t think there will be a way on the Onex to keep them inside the stock cowl. I can probably figure out the plumbing, execution may be a problem I like the simplicity of Peter’s setup/plumbing. Ref: https://sonexbuilders.net/viewtopic.php?f=66&t=6131&start=30#p46432

The worry is heating up the fuel while pumping without the engine running. Peter is using a lower power fuel pump than the Walbro which will mitigate the fuel heating problem. I just received one of the 45 L/Hr to use for initial testing.

Ref. https://www.aliexpress.com/item/32380160597.html?spm=a2g0o.productlist.0.0.32871f56sbQfsA&algo_pvid=4be4927d-f1cd-40a4-bda1-f182f03d1219&algo_expid=4be4927d-f1cd-40a4-bda1-f182f03d1219-0&btsid=0b0a555c16214710569158615ea0a0&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

The lowest profile injectors I have seen are the ones suggested in Jeff’s post.

Ref: https://sonexbuilders.net/viewtopic.php?f=66&t=6131&start=20#p46384

Or maybe these I just stumbled across. These make an attempt to spec the on/off times and are apparently sold with mating connectors.

Ref: https://www.aliexpress.com/item/32292413156.html?spm=a2g0o.detail.0.0.5b775719T2SjLE&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=eacc2810-3a5d-4133-8a8e-3d52f0784781&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:eacc2810-3a5d-4133-8a8e-3d52f0784781,tpp_buckets:668%230%23131923%230_668%230%23131923%230_668%23888%233325%2316_668%23888%233325%2316_668%232846%238109%231935_668%235811%2327179%2339_668%232717%237560%23252_668%231000022185%231000066059%230_668%233468%2315615%23642_668%232846%238109%231935_668%235811%2327179%2339_668%232717%237560%23252_668%233164%239976%23803_668%233468%2315615%23642

Bottom line, left to my own devices I’ll use the lower power pump and the one of the low profile injectors mentioned above. If I go with the 45 L/Hr pump for flight, I’ll probably run redundant pumps for takeoff/landing.

Anyway, I’ll probably have to modify the cowling no matter what. But …, I can’t look at all of the problems at once or I’ll vapor lock. Right now I just need to get a system together and go for an engine start. An engine start would be very motivating

Just gotta keep plugging at it.

Wes

Re: The VeeCU

Posted: Tue Jun 22, 2021 5:47 pm

by imamac96

Wes, have you ever thought of buying a 3018 or similar? Like this: (https://www.amazon.com/Genmitsu-3018-PR … B07P6K9BL3). It’s a small, cheap CNC router that a lot of people use for one-off boards. I think it’s an open-source design so there are a bajillion clones sold everywhere. You really shouldn’t do it in industry, but for you it might be good to have. Of course, the learning curve for CNC absolutely blows. My philosophy is that I don’t factor tools into cost because they hold some resale value if I decide I don’t want them anymore.

Cheers,
Connor

Re: The VeeCU

Posted: Wed Jun 23, 2021 2:00 am

by WesRagle

HI Connor,

I have never heard of that before. Looks pretty cool. But, I don’t really want to go off on another learning curve right now. I’m kinda learned out at the moment. It took much longer than I expected just to layout a simple two layer through hole board. First I had to evaluate several “free” design tools. And it’s hard to evaluate a tool which assists with a task you have never done before:-) Turns out that for a beginner probably the most important consideration is the tools ability to import available models/footprints so you can skip the “Parts Builder” part of the learning curve.

Wes

Re: The VeeCU

Posted: Sat Jul 31, 2021 11:55 am

by WesRagle

Hi Guys,

Quick update on the VeeCU project. Moving along at a glacial pace.

I received my PCB. We’ll call it PCBs for preschoolers. There was only one trace missing I assembled it and it passed a static check on the bench. Next I’ll have to hook up the sensors to the engine and see them work with the engine running.

Here is a pic of some of the bits and pieces that have been collected so far:

I’m going to copy Peter Henry’s fuel distribution scheme. During testing the fuel sump will be replaced with a temperature sensor so I can see how quickly (or not) the fuel pump heats up the fuel.

After a rather lengthy search I found the mating connector for the fuel injector and an affordable crimp tool here:

http://www.cycleterminal.com/index.html

I couldn’t very well start soldering and such on my Wife’s built-ins so I had to clean out a space in the shop. The office has never been used as an office. It turned into a place where discarded items go to die. So, I had to clean it up and give it a fresh coat of paint. Amazingly enough the air conditioner still works.

I don’t want to have to worry every time I fire up the test engine so I installed concrete anchors and bolted the Sonerai to the shop floor.

I need a portal into the ECU during development. So, I took time out to get the CAN interface and display up on what will serve as the control head during development. The CAN peripheral has been updated to support CAN FD (which I don’t need or want) so it took much longer than I thought it would since I had to learn how to make the new peripheral support “Classic Can”.

I can page through any number of displays with the blue button.

I’m going to retrieve my build table from Olney, set it up next to the Sonerai, and build an instrument panel on it. I’ll extend the engine controls and sensor signals so I can watch everything without poking my head into the cockpit. I’m going to mount the fuel system to the table as well. I’ll run both the low pressure and high pressure fuel sources from the table to the Sonerai.

The engine hasn’t been run in about two years. The left front cylinder exhaust valve is leaking badly. But, I’m not going to worry about that just yet. I’ll just change the oil, torque the prop, and see if I can get an engine start running on the carb. That will allow me to hook up sensors and scope the inputs and outputs of the input signal conditioning circuitry and see how well that works.

Forever Forward,

Wes

Re: The VeeCU

Posted: Tue Aug 03, 2021 10:19 am

by WesRagle

Hi Guys,

OK, trouble in paradise.

I took the stubby pipes off the Sonerai and did a test fit of the second hand Sonex pipes I bought.

I should have known it wouldn’t be that easy

I took the pipes, the O2 sensor, and the sensor bungs to the exhaust shop this morning and learned (re-learned) that most shops don’t have the capability of working with 1 3/8" pipe, regardless of the material.

I may have to build a stainless deflector, mount it forward of the firewall, and leave the extensions off but that would put the O2 sensor too close to the exhaust port (24" minimum recommended).

So, this is a problem in search of a solution … Wishing I had an engine test stand.

Wes

Re: The VeeCU

Posted: Tue Aug 03, 2021 11:00 am

by Bryan Cotton

Are you flying the Sonerai or will you just be ground running? You could turn the pipes around backwards.

Or just build some mild steel pipes.

Re: The VeeCU

Posted: Tue Aug 03, 2021 11:16 am

by WesRagle

Hey Bryan,

Just ground runs. That’s an interesting idea. I’ll go check prop clearance (I do have to load the engine). Back in a flash.

Wes

Re: The VeeCU

Posted: Tue Aug 03, 2021 11:23 am

by WesRagle

Good thought, but the same problem.

Wes

Re: The VeeCU

Posted: Tue Aug 03, 2021 11:39 am

by WesRagle

Hi Bryan,

Bryan Cotton wrote:Or just build some mild steel pipes.

The guys at the exhaust shop can’t do anything with 1 3/8" except weld it. I went through an pretty exhaustive search of shops in the past and nobody has the equipment for anything smaller than 1 1/2". I would have to find pre-bent pieces that could be welded together. I’ll see what I can find.

Wes

Re: The VeeCU

Posted: Tue Aug 03, 2021 12:06 pm

by Bryan Cotton

https://www.greatplainsas.com/0286-/-u- … t-kit.aspx

Re: The VeeCU

Posted: Tue Aug 03, 2021 1:08 pm

by WesRagle

Hi Bryan,

Bryan Cotton wrote:https://www.greatplainsas.com/0286-/-u-build-exhaust-kit.aspx

Thanks. I’m looking. I do have to say though, I’m a little gun shy.

I haven’t been happy with my Zenith carb. It’s not going to let me down but I have to set it slobbery rich to keep my right rear cylinder from over temping in both EGT and CHT during takeoff/climb. Then in cruise I have no way to dial it back. So …, I want to switch to an AeroInjector. Just like my exhaust situation, it’s not as easy as it looks. I need to change my “intake tubes”. I ordered a part from GPAS. The pic of the part on their web site showed this:

That’s not what I received. What I got I already had. I haven’t been able to contact them. Their phone mail box is full and they won’t answer my emails. For the time being I have a $200 paper weight. I think there have been some health problems that led to this situation. I don’t know. But until I can get some response from them I’m hesitant to place any more orders.

We’ll See,

Wes

Re: The VeeCU

Posted: Tue Aug 03, 2021 3:10 pm

by WesRagle

So here is a pic of the “stub” pipe I pulled off the engine slid over the forward part of the Sonex exhaust.

If I could get a bent piece of that I think the problem would be solved.

Wes

Re: The VeeCU

Posted: Thu Aug 05, 2021 1:34 pm

by WesRagle

Hi Guys,

I made the trip to KONY yesterday and picked up a “Build Table”. I mounted the fuel tank to the table this morning. I should have some pipes later today with 1 3/8" I.D. that I can use to cobble together some exhaust that will be good enough for development work.

BTW, at KONY they train pilots to fly militarized crop dusters. It’s fun to count the number of times new students touch down each landing Cool looking planes, and much larger than the pictures make them look.

If you look closely at the steps it gives you an idea of the size.

Wes

Re: The VeeCU

Posted: Thu Aug 05, 2021 6:53 pm

by WesRagle

Hi Guys,

Ok, turns out you can get 1.5" mild steel with 0.0625 wall thickness which makes for a perfect slip fit onto the 1 3/8" Sonex pipe. Pretty cheap too.

I won’t even have to sacrifice my Sonex pipes. I’ll just slip it on, apply a couple of SS pops (as close to the end of the Sonex pipe as practical), and seal the joint with aluminum tape. This will actually be better than using the Sonex end pipes because I can get farther from both the exhaust valve and the exhaust exit with the O2 sensor.

Forever Forward,

Wes

Re: The VeeCU

Posted: Sat Aug 07, 2021 6:31 pm

by WesRagle

HI Guys,

The pipes are now at the muffler shop to have the O2 bungs welded in.

While waiting on the pipes I needed to make sure the engine would run. The goal is to take this one step at a time. First step is to start the engine without changing anything. So, the first engine run will be with 100LL.

Hooked up the new battery and charged it.
Changed the oil and added some cam guard (better late than never).
Torqued the prop.
Checked the timing.
Checked the valve lash.
Pulled the plugs.
Crank until I had oil pressure + 10 seconds.
Replaced the plugs.
Ran fuel from the bench to the Sonerai and checked for and fix leaks.
Master on, Mag Hot, Throttle cracked, Mixture full rich, count 1 2 3, and Start.

After two years, the engine roared to life immediately. It scared me I had the throttle a little bit too “cracked” and the canopy hit me in the head. So, I took the canopy off. That took all of 30 seconds. 15 of that was figuring out how to take it off.

I shut the engine down and started wiring. Since there is nothing more frustrating than fighting grounding problems, I started there.
I ran a ground from the engine block to the negative terminal of the battery. Then I ran a 12 gauge ground from the negative terminal of the battery over to the work bench. I have a handy little widget that plugs into a three prong outlet and provides two connections to safety ground. The entire setup will be grounded to the safety ground. Maybe I won’t blow up any test equipment.

I made it as far as wiring the two secondary ignition leads and the P-Lead before I ran out of steam.

Oh yea, I also got an inexpensive 13.6 V (I think), 10 A power supply to power everything except the starter.

All of the signals will eventually get wired to terminal strips but I couldn’t resist having a look at the P-Lead and low tension side of the secondary ignition. I’ve been thinking about those signals a long time. It was nice to finally meet them.

P-Lead pics:

Looks like about 150 Volts peak. Easy to see when the plug fires, and for how long.

Secondary Ign. pics:

I turned the peak picker on for the first pic of the secondary. The scope measured a peak voltage of 468 V. You can also see two distinct steps in the wave form. It’s like one plug burned a lot longer than the other. Wonder if the wasted spark or the “real” spark burned longer.

There are a lot of questions that can be answered with a running engine. Like: How high would the voltages go if the plug never fired? The list is long but now I can start getting some answers. Great fun.

Forever Forward,

Wes

ArchiveBot · May 23, 2021, 5:01am

Re: The VeeCU

Posted: Sun Aug 08, 2021 2:05 pm

by WesRagle

Hi Guys,

I changed to 5 Ohm coils this morning. I took another look at the voltage at the trigger input. Virtually no change.

I did take the time to think about what I was looking at this time. Both plugs probably do fire at the same time. The spark lasts just about 1 mSec. When the spark stops the primary “rings” for a while and then settles in on 12V power until the trigger magnet passes at which point the secondary ignition grounds the lead again.

Wes

Re: The VeeCU

Posted: Tue Aug 10, 2021 6:22 pm

by WesRagle

Hi Guys,

A little progress on the test bed today. Trying to do machine work with a ruler and hand drill takes me forever but with some persistence I managed to make the adapter plate so I could use a clamp to mount the IAT/MAP sensors.

Since I started down kluge lane, I kluged in a MAP port as well (needed for the fuel pressure regulator reference). I sealed around the clamps with gasket maker and cinched the clamps down. I let them sit overnight and tighten them good in the morning. Keep in mind that this is not meant to be an airworthy setup. It’s only purpose is to support development of the ECU.

Tomorrow I’ll splice onto the sensor leads and wire them over to “Mission Control”

I’ve been thinking about how to measure engine temperature for “Warm Up Enrichment” without adding a thermocouple and all that that entails. The temperature reading doesn’t have to be super accurate, just an indication of Cold, Cool, Warm, etc. Poking around I came across the “CB Performance Gen 4 EFI Installation Manual”
(Ref.http://cbperformance.net/pdf/Gen4EFI.pdf). What’s shown on page 2 looks like a pretty good solution. We’ll see.

Wes

Re: The VeeCU

Posted: Thu Aug 12, 2021 2:54 pm

by WesRagle

Hi Guys,

I’ve reinstalled the modified induction system. Since I was still waiting on the pipes I decided to mock up the fuel system.

Since I don’t like the idea of pumping 10 to 20 gallons of fuel per hour through the cockpit, I’m basing my fuel system on what Peter Henry presented with some minor modifications.

The front of the mock up:

The back of the mock up:

Since I couldn’t find a 40 micron screen for the gascolator I caved and bought a 40 micron filter. That’s it on the back of the mock up. And, since I had a 40 micron filter, I decided to plumb it before the gascolator and remove the screen from the gascolator. With that done, what was a gascolator is now just a fuel distribution manifold. After staring at my blue manifold for a while what it started to look like a pretty cool manifold with a built in miniature vented surge tank. So, that’s how I plumbed it. The cheap temperature gauge, plumbed where the AeroInjector will eventually get it’s fuel, was pretty useless.

I plumbed all of the low pressure lines with clear vinyl so I could watch it work. I turned the fuel on at the tank and the lines filled pretty much like you would expect with the surge tank vent filling to fuel level much like a sight gauge.

So, I applied power.

First surprise, my 3 Amp bench supply went into current limit trying to drive my 2.5 amp fuel pump. Latter measurements showed that the pump consumes 3.5 amps in the configuration shown.

OK, substitute a 10 Amp, 12V power supply and a current meter for the bench supply. Power on and away it went.

Second surprise, the fuel pressure regulator started making vapor almost immediately. The vapor beneath the regulator outlet continued to build until if spanned the length of the connection between the regulator and the blue manifold input. It doesn’t show up in pictures very well but here is an attempt.

Every now and then the surge tank vent would just burp a bubble.

And no surprise, there was never any vapor at the fuel pump input.

I feel pretty good about that setup. I was hoping I wouldn’t have to plumb anything back through the firewall but I think I’ll have more confidence in the system if it can release vapor without passing it through the fuel pump.

After about 20 min. of continuous operation the fuel pump was too hot to hold your hand on it for over 5 seconds. The gold manifold was just a little less hot. I didn’t expect it to take that long to heat up.

It might be better to move the 40 micron filter to the bottom fuel outlet. That way switching to the AeroInjector would also serve as an emergency fuel filter bypass. We’ll see.

Wes

Re: The VeeCU

Posted: Thu Aug 12, 2021 7:06 pm

by GraemeSmith

So is the vapor associated with the heat from the pump, or negative pressure, or both?

Can you submerge the pump in the fuel tank to keep it cool? (Not necessarily as dangerous as it sounds)

Re: The VeeCU

Posted: Thu Aug 12, 2021 11:10 pm

by WesRagle

HI Graeme,

GraemeSmith wrote:So is the vapor associated with the heat from the pump, or negative pressure, or both?

I’m not sure whats causing it. The rate of formation isn’t as strongly correlated with fuel temp as I would have expected. Some of it may just be air that was trapped in the gold manifold. When you turn the system on stone cold the down run from the fuel pressure regulator fills and then the little bubbles start forming at the regulator output until they totally fill the down run. It’s funny though, the bubbles seem reluctant to enter the “blue manifold”. It’s almost as if the bubbles form simply as a reaction to the pressure drop and turbulence as the fuel exits the regulator.

GraemeSmith wrote:Can you submerge the pump in the fuel tank to keep it cool?

Actually I was very happy with how long it took the fuel to heat up. What I was testing was a worst case scenario of the fuel pump left on with the engine not running. Since the volume of fuel in the closed loop is small I expected to heat rapidly. That 40 watts of power consumed by the pump ends up either heating the fuel or radiating. It looks like equilibrium is going to be reached at somewhere around 30 F. Deg above ambient. I would know better if the POS temp gauge would have worked. In normal operation, even at idle, the fuel will be changed out several times an hour so it shouldn’t heat much above ambient.

I drained the system to hook up an injector. When I powered it back up the air in the system was purged quickly through the vent line. I had the end of the vent about 16" above the fuel level the air came out so quickly the vent was puking fuel. Once the air is out and the system stabilizes the fuel level in the vent line is about 1" below fuel level reflecting the slight vacuum inside the blue manifold. I’m pretty happy with the way it’s working.

Now the bad news for the day. I got my pipes back from the exhaust shop. The guy at the shop bent one of the pipes and I brought it home to make sure it would work and check where I wanted the bung welded. I marked the bung on the pipe and wrote a note telling him the bung was marked on the bent pipe and to make both pipes identical. My wife was going to town to get new tires and volunteered to pick the pipes up for me. This is what she came back with.

He remade a pipe out of some stock he had but it looks like the slip joint may not work. I’ll check tomorrow.

I did a flow test on one of the injectors. The seller gave the flow in grams per min. I somehow convinced myself that what they really meant was cc per min. Looks like I was wrong again. I bought 190 grams/min injectors. Here is a pic of 1 min. worth of fuel.

The fuel regulator that came with the gold manifold is 2.7 bar. The injectors were rated at 190 grams per min at 3 bar. The flow correction factor for differing pressures is (square root (P/P0)) Where P is the actual pressure and P0 is the referenced pressure.

So back calculating the specific gravity of the blue stuff in the beaker.

Specific Gravity = (grams/min * (square root (P/P0)))/Volume

Specific Gravity = 190 * square root (2.7/3) /250

Specific Gravity = 190 * .94 / 250

Specific Gravity = 0.7144

Sound about right? Dang it! I’m looking at 4 gal/hour per injector @ 100% duty cycle.

Anyway, minor set backs. Tomorrow is another day.

Wes

Re: The VeeCU

Posted: Fri Aug 13, 2021 4:47 am

by GraemeSmith

100LL ATSM - SG 0.68-0.74 @ STP

Re: The VeeCU

Posted: Fri Aug 13, 2021 10:38 am

by Bryan Cotton

Wes,
What fuel pressure are you running? I looked back through the thread and if it is there I missed it.

We have replaced the fuel pumps in our 80’s vintage motorcycles with Holley pumps. There are solid state electronics on the pump that turn it on and off to regulate pressure. The advantage of an on-off pump is much less power demand for low flow demand. The old pumps did the same thing but had contact points in them to work.

Re: The VeeCU

Posted: Fri Aug 13, 2021 3:57 pm

by WesRagle

Hi Bryan,

Bryan Cotton wrote:What fuel pressure are you running? I looked back through the thread and if it is there I missed it.

I’m running 2.7 bar. That’s what the regulator Ross provides with the “Gold Manifold” produces. A beautiful piece by the way.

Bryan Cotton wrote:We have replaced the fuel pumps in our 80’s vintage motorcycles with Holley pumps. There are solid state electronics on the pump that turn it on and off to regulate pressure. The advantage of an on-off pump is much less power demand for low flow demand. The old pumps did the same thing but had contact points in them to work.

I think the type of system you are describing is a returnless type. While discussing FI off line with another builder he mentioned the possibility of using PWM to control power consumption. I poked around the web for a while and came across this:
https://walbrofuelpumps.com/walbro-fuel-pump-kit-sniper-fitech-efi.html

Of particular interest is the statement:

This kit must always be installed with a return line to the fuel tank and may never be powered with a Pulse-Width Modulated (PWM) power source. PWM operation can seriously damage Walbro gerotor pumps. These pumps are not benefitted by PWM speed control. Simply disable the PWM feature if you are running a FiTech GoEFI system with PWM fuel pump speed control capabilities.

So, I think I’ll leave well enough alone and just provide whatever current the motor requires.

The burning question for me is how low can the voltage go and the pump continue to make rated pressure? I don’t have the equipment to answer that question … yet

Wes

Re: The VeeCU

Posted: Sat Aug 14, 2021 12:25 am

by WesRagle

Hi Guys,

A little progress today.

I have six injectors. While set up to do so I flow checked each injector. I was pleasantly surprised that the flow of each injector is the same. Also, the resistance of the injectors is more than 12 Ohms.

I relocated the fuel system to a more permanent temporary location below the fuel tank

I knocked the anatization <sp?> off of one of the plugs in the fuel tank. I drilled and tapped the plug so I could add the tank to the ground system. It all Ohm’ed out good.

I put the injectors away. The fuel pump apparently had some oily “stuff” in it when I received it. I decided to use the last of the 100 LL to flush as much of it as I could out of the system. I ran the hose that had been connected to the injectors to an old fuel can and turned the pump on. I heard the fuel pump start cavitating. A quick look showed an empty vent line. Turns out at zero pressure the fuel pump flows enough fuel to start sucking air through the vent. I hadn’t considered that.

So, back out with the injectors. Hooked everything back up. I turned the pump on, waited for the system to stabilize, and marked the fuel level in the vent line. Then I turned the injector on which produces an approximate 4 gal/hour flow. I marked the new fuel level in the vent line. The 4 gal/hour flow sucked the level down about 1 1/2 inches. Assuming a linear relationship 8 gal per hour (~ max flow) would pull the level down 3 inches. If I end up installing the system I’ll ensure 5 inches of head from the fuel tank outlet and the “blue manifold” vent in the three point attitude. That should allow me to run all of the fuel out of the tank without sucking air.

Edit: After thinking about it some more, it has to be the restriction of the 40 micron filter that is causing most of the suction on the vent line. I’ll try moving that filter to the bottom of the “blue manifold” sometime in the future.

EDIT #2: After thinking about it even more, the 40 micron filter has to be moved downstream of the vent line else a partially clogged filter would cause the pump to suck air.

Forever Forward,

Wes

Re: The VeeCU

Posted: Tue Aug 17, 2021 9:28 pm

by WesRagle

HI Guys,

Well, the pipe the man made me from local stock to replace the one he messed up didn’t work. So, new pipe on order.

Meanwhile I’ve been working on “Mission Control Center”. Most of the wiring is done and the signals have been run to terminal strips. I pulled the fuses in the Sonerai and wired the various power switches over to the table. I’ll fuse and switch them at the panel on the table. The control panel on the table is in work. Throttle cable 2 weeks out.

Wires secured:

Panel in work:

I’ve been obsessing over the P-Lead signal. The more I look at it the more I hate it. Noisy, high voltage, probably varies from plane to plane and engine to engine. I didn’t want to but I think I’m going to cut into one phase of my alternator and get my backup signal there. The only thing the “backup signal” will be used for is to support straight batch injection in the event of a secondary ignition failure in flight.

The engine I’m working with has three identical (except for phase) signals. I wonder if someone could tell me what the AeroVee has available at the alternator output?

Thanks,

Wes

Re: The VeeCU

Posted: Wed Aug 18, 2021 3:45 pm

by WesRagle

Hi Guys,

I pulled a single phase of the alternator over to the bench. This is what I saw.

Alternator without regulator (Raw alternator):

Alternator through a 4.7K and a 3V zener.
Alternator with regulator in the circuit.
Alternator through an opto-isolator with output pulled to 5 volts.
Alternator with regulator in the circuit.
P-Lead showing six alternator pulses per revolution.

I think I’ll go with the isolated solution to keep the digital ground as isolated as possible.

Wes

Re: The VeeCU

Posted: Wed Aug 18, 2021 8:50 pm

by WesRagle

Hi Guys,

I know I’m jabbering so please, if you’re not interested ignore me. It’s just that I find data acquisition fascinating.

I hooked up the MAP sensor for the first time to get a feel for what that looked like. I took a reading at ambient and according to the altimeter setting at the local airport the reading was 1 In. Hg. off. I’ll study that more later but it appears that a single point cal is probably called for.

Edit: A fellow builder pointed out that by comparing my MAP reading with altimeter setting I had neglected to account for my elevation above sea level which is right at 1000 ft (~1 in.Hg). So it looks like my MAP reading was pretty much spot on. I feel much better now.

Most folks would guess that it’s pretty turbulent in the intake manifold. I wanted to know: Just how turbulent is it? The manufacturer of the MAP sensor says it has a response time of 1 mSec. They never say exactly how that’s calculated but I assume that at worst it means that a step change in pressure will move to within 63% of the final reading with in 1 mSec (one time constant). Anyway, pretty fast. The following image was taken with no analog filtering. Again, I included the P-Lead as a reference.

As you can see, there is approximately 600 mV of peak to peak noise. That amounts to about 4 InHg of peak to peak noise. You can study the image and read more into it as far as timing and when an intake valve is open and a cylinder is sucking etc.

Anyway, now I know. I will add some analog filtering and average the AtoD readings over an integer number of cycles of the waveform (revolutions).

Wes

Re: The VeeCU

Posted: Wed Aug 18, 2021 9:10 pm

by GraemeSmith

I’m loving your Rigol scope!

Re: The VeeCU

Posted: Fri Aug 20, 2021 12:07 am

by WesRagle

Hi Guys,

GraemeSmith wrote:I’m loving your Rigol scope!

I’m having a lot of fun with it. It has a lot of “Nice to Have” capability I’m not using. One thing I would like to do with it is mount a knock sensor to the VW and use the FFT function of the scope. It would be cool to see if you could pick out knock, valve lash, etc in the spectrum. But, I’m going to run the current project to ground before going off on a science project.

Speaking of which, I have to gloat just a little.

I totally lose focus switching back and forth between Nust & Bolts and Bits & Bytes so I’m going to finish setting up the test bed before switching back to electronics. Obviously fuel flow is an important parameter for ECU development. From my experience the FLOSCAN transducer is much more accurate than the Gold Cube I am using in the Onex. I want a FLOSCAN. The problem is the current price at Aircraft Spruce is $366.00.

There aren’t many perks to being an Engineer but one perk is being able to talk sales reps out of free samples. I had a flashback today and remembered talking a FLOSCAN rep out of a sample some 15 years ago. I rummaged through the boxes of unused airplane parts and found it!

Complete with K-Factor. 3499 pulses per gallon @ 16 GPH.

SCORE!!!

Wes

Re: The VeeCU

Posted: Thu Aug 26, 2021 12:52 am

by WesRagle

Hi Guys,

I’m waiting parts. While waiting I decided to fool around with the fuel system some more. One thing I wanted to try was substituting a small manifold for the gascolator (surge tank) I had tried previously. I also relocated the main fuel manifold over to the firewall and moved the 40 micron fuel filter down stream of the vent. The relocation of the main fuel manifold resulted in approximately 7’ of high pressure supply hose and 7’ of low pressure return hose. So, much more fuel volume being circulated.

Here’s what the manifold lookes like.

Top left is the pressure regulator return line. Top center is the vent. Top right is fuel in from the fuel tank. Bottom left is fuel to the RevFlow carb. Bottom right is fuel into the fuel pump.

When I turned the system on for the first time (dry) the vent did a decent job of eliminating air from the system. It didn’t get it all the first pass but within a few circulations everything was steady state.

This test was run with Shell 93 octane. After about five minutes I took note. The fuel wasn’t at all hot but the vapor forming at the fuel pressure regulator output seemed more pronounced than what I had seen with 100LL.

Here is what it looked like at the regulator output.

It didn’t matter how long I waited, the fine bubbles just kept coming. They formed a steady parade in the return line making the 7’ trip and entering the previously pictured manifold.

Again, the manifold would catch some of the bubbles but not all. I could definitely hear it and see the pressure fluctuate on the pressure gauge when a bubble slipped by.

Tomorrow it’s back to the “surge tank” and I’ll see how that does with auto gas.

Wes

Re: The VeeCU

Posted: Thu Aug 26, 2021 1:13 pm

by WesRagle

HI Guys,

OK, I took the screen back out of the gascolator and replaced the small manifold with the gascolator. Again, fuel inputs and vent on the top and fuel outlets on the bottom.

This is the same thing as the small manifold I tried except the diameter of the path from fuel input to output is much larger so the vapor can’t get caught up in the flow. Problem solved, no vapor at the fuel pump input so no fluctuation in pressure.

Pic of the vapor making its way around the last turn and into the gascolator.

Things I think I learned:

Fuel pressure regulators make vapor at the outlet.

EDIT: I just walked out and turned the pump on again. There was a delay before the vapor appeared at the regulator output and then it appeared suddenly. So …, it might be that the pump itself is generating the vapor. Wish I could see through high pressure hose

The vapor is not in a hurry to condense back into the surrounding fuel.
Fuel pumps don’t like vapor at their input. Vapor causes the pump speed to surge and the pressure to fluctuate.

In my opinion the vapor in the lines needs to be eliminated. It may be that the easiest way to eliminate the vapor is to stay on the beaten path and return fuel to the fuel tank. I’ll have plenty of time to think about that but for now I’ll just leave it alone and press on.

BTW, I did finally get two pipe extensions I could use.

Wes

Re: The VeeCU

Posted: Fri Oct 29, 2021 1:34 pm

by WesRagle

HI Guys,

This time of year is perfect around Tx. for camping in the state parks. So …, I’ve been totally distracted.

Just back from Caprock Canyons State Park.

One problem with park camping is: What to do after you have walked all you want to (and all the beer is gone)? A friend had an eBike along on this trip and I’m hooked. These things are great. The only problem is finding a good Old Man Bike that will actually haul you out of a canyon on the multi-use trails. Since the inexpensive hub drive bikes aren’t up to the task I’m going to try and build an inexpensive 1000 Watt mid-drive bike. I hope to build one like that shown in this video with different bars and a smaller front sprocket to help with hill climbing. I know nothing about bikes so a bit of a learning curve involved. Parts on order. Another distraction.

https://www.youtube.com/watch?v=Qg5Z9csJZl8

OK, back to the VeeCU.

I attached the injectors I chose to the red logs. I don’t consider the install airworthy but it will keep the VeeCU project moving along. You have to mount the injectors a low as possible in the “Red Log” to get a straight shot down the intake. Installing the Red Log on this conversion requires a spacer to clear the plugs.

I found an inexpensive CHT sensor to enable warm up and cranking enrichment. I tapped a 1/8" NPT hole in the fin. I’ll screw the sensor in and secure it with an NPT nut and high temp lock tight.

Data from 100 Deg F upward is available here:https://www.autometer.com/sensor_specs I generated the curve from 32 Deg F to 100 Deg F by placing a thermometer and the sensor in an ice bath and taking data as the water warmed up after the ice melted. I also got one more data point a -7 Deg. F by placing the thermometer and sensor in the freezer. That will be “good enough” for its intended purpose.

I have a Walbro fuel pump I’ll be testing. I also have a MAP sensor for the EIS to help verify the accuracy of my calculations.

I’m currently working on a cooling shroud to extend run time without over-heating.

The long vernier control cables finally came in last week. Now I can route everything over to the work bench.

I truly wish one of you mechanically minded folks would consider taking on the task of designing a generic EFI intake that would bolt right on to the VW heads.

Wes

Re: The VeeCU

Posted: Sat Oct 30, 2021 5:23 am

by GraemeSmith

How are you going to handle getting (outside preferred?) filtered air into the “red log” manifolds?

Re: The VeeCU

Posted: Sat Oct 30, 2021 1:28 pm

by WesRagle

Hi Graeme,

The general idea is to simply modify the intake logs and leave the rest of the induction system in tact. The ideal throttle body would be an AeroInjector but I intend to use what was supplied with the plane, a RevFlow.

The builder of the test bed simply took intake air from beneath the cowl with no filter. I’ll do the same for the “Proof of Concept”. If the experiment makes it to “Prototype” and is installed on my Onex I’ll use the filtered cold air induction I have. The problem I’ll have with the Onex is switching from the Zenith to an AeroInjector so as to provide idle cutoff while running on EFI.

Wes

Re: The VeeCU

Posted: Sat Nov 06, 2021 3:55 pm

by WesRagle

HI Guys,

OK, I’m just about finished with the cooling shroud.

It started life as a Sonex baffle kit. I didn’t use much of the kit but it did get me started. Mostly made from leftovers, scrap, and Home Depot aluminum. I think it’s plenty stout.

I need to secure the wiring and add some fasteners and then I can move on to making sure all the sensors are working properly.

Now for a break. Santa Clause came early so I need to get the Fat Tire assembled, take some measurements, and get the parts on order for the electrification.

Wes

P.S. I forgot to turn the flash off on the camera so the pics look pretty bad. Sorry.

ArchiveBot · May 23, 2021, 5:02am

Re: The VeeCU

Posted: Wed Dec 01, 2021 8:27 pm

by WesRagle

Hey Guys,

I got some time in on the project.

I drained the fuel and donated it to my lawn mower. Inserted the FF transducer into the fuel system, got 5 gal of fresh fuel, and calibrated the FF. I left the gascolator (used as a vapor separator) in the system so I could measure FF with fuel injection using a single FF transducer. I also left the original fuel pump in place. I will wait to test the Walbro until I have a variable voltage bench supply so I can see how the capacity of each pump varies with voltage.

I moved most of the switch functions over to the bench and wired the “Central Command” instrument panel. The only control left in the aircraft is the Master Switch which enables the starter to run off of the battery. All other power is provided by the bench supply.

Looking ahead, I will probably implement variable timing first. So, I decided to fashion a pointer to help me watch timing changes. The case has a very convenient place to mount a pointer.

It was at that point that I realized that I wouldn’t be able to see the pointer from a safe position so I remade the top of the cooling shroud from Lexan so I could safely observe a timing light.

I plumed and wired all of the fuel injectors. I also plumed manifold pressure to both the EIS MAP transducer and the fuel pressure regulator. I pressurized the fuel system. No runs, no drips, now errors. A lot of FI hose. Seems like a fuel rail might be neater.

I added fuel and fired the engine to make sure I hadn’t introduced any severe manifold leaks. All good there. I got to see the 02 (Mixture) gauge work for the first time. Very noisy and a very lean indication at idle. That is probably due to misfires rather than an induction leak. The indication settles down as throttle is added.

All of the pertinent signals have been wired to the bench ready for use.

Really the only thing I need to add to the test bed is a timing light. I’ll probably install it in the timing shroud so it’s easy to turn on and use.

Just about out of excuses. Going to have to switch back to electronics soon. Oh yes, I have a low oil pressure indication of approximately 20 PSI at power. Swapped sensors with identical results. I might try one of these: https://www.jbugs.com/product/9198.html?utm_content=shopping&gclid=EAIaIQobChMIp6zS0urD9AIVxStMCh2zuwtAEAQYAiABEgLb3_D_BwE

I also need to go through the EIS as make sure the limits are set properly.

Forever Forward,

Wes

Re: The VeeCU

Posted: Wed Dec 01, 2021 10:47 pm

by GordonTurner

Onwards to infinity Wes!!!

Graeme says flux gates are on backorder…so keep hacking.

Following…far behind. Gordon

Re: The VeeCU

Posted: Thu Dec 02, 2021 11:40 am

by WesRagle

Hey Gordon,

GordonTurner wrote:Graeme says flux gates are on backorder…so keep hacking.

I believe it’s out of production. Per O’Reilly, “This item is not available for purchase”. I picked up the last one:-) Rumor is that ACS will have some in “New Old Stock” soon.

Wes

Re: The VeeCU

Posted: Thu Dec 02, 2021 8:11 pm

by GraemeSmith

WesRagle wrote:I believe it’s out of production. Per O’Reilly, “This item is not available for purchase”. I picked up the last one:-) Rumor is that ACS will have some in “New Old Stock” soon.
Wes

We had a 182 and engine out at a local airport a couple of years ago. The reporter got the inside scoop…

Re: The VeeCU

Posted: Fri Dec 03, 2021 2:53 pm

by WesRagle

Hi Guys,

Just about finished with the test setup.

I jumped the trigger on my old timing light and strapped it to the top of the cooling shroud.

I checked the mag timing and it was dead on. I added a 3 Deg. after TDC mark and adjusted the secondary timing to 3 Deg. after TDC.

As expected, the engine starts easier but even at idle runs like crap on the secondary.

I couldn’t resist running the engine some to get my feet on the ground. I anticipate that the initial fuel map will be generated by running on the RevFlow, leaning to peak power, and dividing FF by 4 to calculate injector pulse width. So, I wanted to work vernier mixture control some and see how the A/F indication and engine parameters responded. I was surprised at the amount of fuel savings available and how sensitive the mixture control is as the engine starts to lean. Here are a couple of data points. Left to Right, Top to Bottom: RPM MAP FF Oil Temp/Oil Pressure CHT/EGT

Full Rich:

Just Rich of Rough:

I forgot to check the EGT spread Oh well, there will be plenty of time for that. At the end of the run I did return the mixture to full rich and the CHTs started dropping indicating that the cooling shroud will be sufficient. The Oil Pressure adjustment gizmo is on order.

Wes

Re: The VeeCU

Posted: Sat Dec 04, 2021 11:52 pm

by n502pd

I have followed along for a bit, but I now have to chime in: WOW!! What a great undertaking, and I really appreciate your methodolgy and process! Again , WOW!!
And I do think a fuel rail would be better, but the proof of performance of your design and process would not be altered very much from what it is now if a fuel rail is used.

I am intrigued with the F/A mixture system you have, and wonder if it is applicable to non injected engines> I did have one on a truck many years ago, but was not pleased with it. Should I assume you use O2 sensors, in just one stack, or do you have some other setup?

Again, WOW, I am impressed, Wes! Carry on!!!

Re: The VeeCU

Posted: Sun Dec 05, 2021 2:59 pm

by WesRagle

HI Joe,

Thanks. I’m having fun with it. But …, I haven’t really done anything yet. I’m just fix’in to begin to start to get ready to do something. I woke up this morning with visions of sugar plums dancing in my head but soon realized that I’m not finished with the test bed yet. When I started thinking about patching the various boards together and testing concepts I came to the part where I had to wire to the terminal strip. That’s not going to work. I need an interface panel so I can unplug, modify, plug back in, and test.

n502pd wrote:I am intrigued with the F/A mixture system you have, and wonder if it is applicable to non injected engines> I did have one on a truck many years ago, but was not pleased with it.

The old O2 sensors weren’t very good. They switched quickly from rich to lean indication at stoichiometric. The newer wide band sensors have a much less abrupt transition and so can be used to read the A/F ration. The system I’m using is made by “Innovate” and is readily available. The sensors are not compatible with leaded fuel.

n502pd wrote:Should I assume you use O2 sensors, in just one stack, or do you have some other setup?

I have a bung in each stack but right now I’m just reading the right stack. The reading is still a little noisy but that’s no different than what I’ve seen on YouTube videos. It might be that I have the sensor too close to the end of the exhaust pipe and my exhaust gasses are being polluted with fresh air :-).

Wes

Re: The VeeCU

Posted: Sun Dec 05, 2021 8:38 pm

by Zack

WesRagle wrote:The VeeCU will intercept the ignition pulses coming from the secondary ignition module and use those pulses, in lieu of a crank sensor

I’m just getting caught up on this interesting thread. Check out how these guys picked up timing from an equally old engine design. Go to 10:20 https://www.youtube.com/watch?v=HKIjsXUMvhc

Re: The VeeCU

Posted: Sun Dec 05, 2021 9:52 pm

by WesRagle

Hi Zack,

That was interesting. I watched the whole thing. What’da’you think? $250,000 for that engine? I wish that guy would spend a little on us and develop a casting for a good universal FI ready intake log

When I first started thinking about fuel injection I was interested in sequential FI. The only CAM sensor I could find was this: https://thedubshop.com/mini-cam-sync/. The more I read the more I became convinced that sequential isn’t needed for an aircraft application. As I understand it the automotive market was driven to sequential FI to meet emission requirements. The idea is to always inject fuel against a hot, closed, intake valve, just before the intake stroke, to better vaporize the fuel and help with hydrocarbon emissions. Not sure though.

Using the secondary ignition pulses at least gives the opportunity to implement true semi-sequential injection. The injectors I installed will operate at just below 50% duty cycle at 100% power. So, I can inject twice on either the up strokes or the down strokes. One of the experiments I look forward to conducting is switching between those options. If I inject twice against a closed intake valve will it help with cylinder head cooling? If I inject once against a closed intake valve and once on the intake stroke will the intake stroke injection help cool the charge and improve cylinder filling? I don’t know. It may make no difference at all but it will be fun to find out.

Wes

Re: The VeeCU

Posted: Mon Dec 06, 2021 11:20 am

by Zack

It’s a great show, and like an apprentice of old you can pick up some interesting things watching a master at work.

I think the reason for sequential FI is quicker response to changing conditions (RPM, manifold pressure) in an automotive application. I think you’re right, it’s not needed for an aircraft application. I look forward to your testing!

Re: The VeeCU

Posted: Mon Dec 06, 2021 5:13 pm

by WesRagle

Junk again.

China seems to always disappoint. I wish Amazon would clearly identify the country of origin on products they promote so I could avoid this type of stuff.

Do you see a male connector?

Wes

Re: The VeeCU

Posted: Mon Dec 06, 2021 7:15 pm

by GordonTurner

Chinese stuff, including the plague itself, is a plague of awful stuff. I try really hard to avoid it but it’s not always possible.

Amazon is really not a source for stuff that’s not made in China.

Re: The VeeCU

Posted: Mon Dec 06, 2021 8:28 pm

by WesRagle

GordonTurner wrote:Amazon is really not a source for stuff that’s not made in China.

Yea, I know. It’s so easy to get seduced with a kit that’s cheap and will be on your doorstep tomorrow, free shipping. I’m just anxious to get past setting up the environment so I can move on to the fun stuff.

Found this: https://www.displaythisway.com/Middle-Atlantic-UCP-Module-4DB9.aspx. Thought I would be past this quickly.

Wes

Re: The VeeCU

Posted: Fri Dec 30, 2022 7:14 pm

by WesRagle

Hi Guys,

I’ve been away for a while and will be away for a while longer but …, I intend to get back to this project as soon as I finish with another long over due project.

In the meantime I’ve been trying to plot a path forward with the VeeCU. When I last worked on the project I was getting somewhat depressed. I was trying to cover every failure mode and the solutions always added complexity, cost, weight, current draw, … I know that the AeroInjector is supposed to be the ultimate backup and mitigate a lot of my concerns but imagining a failure on initial climb out from a short strip kept bothering me. In fact, air restarts in general bother me.

Long story short, while considering per cylinder fuel trimming, it occurred to me that per cylinder trimming is just making adjustments to the base fuel map on a cylinder by cylinder basis. Then it occurred to me that the AeroInjector supplies a base fuel map that just needs some per cylinder trimming. You can probably see where this is heading. Why not just run the two systems in parallel?

The tuning process would consist of adding fuel to lean cylinders to bring them in line with the rich cylinders. I can imagine this working with the results of an EFI/Fuel Pump failure being a momentary lean condition which could be corrected by manual mixture control.

Anyway, If this is a workable approach a lot of good things happen. No redundancy needed, no reversionary modes needed, no complex control head needed, smaller fuel pump (less current) required. Can’t wait to finish what I’m working on so I can get back to this project and explore this approach.

I don’t know, The Veequalizer

Happy New Year to All,

Wes

Re: The VeeCU

Posted: Sat Dec 31, 2022 11:29 am

by Area 51%

WesRagle wrote:Do you see a male connector?

I see a couple that possibly “identify” as male.

Re: The VeeCU

Posted: Tue Oct 17, 2023 9:44 pm

by WesRagle

Just a snippet of information archived here so it won’t get lost.

I contacted Dynatek and asked:

I have a pair of 5 Ohm (black) and a pair of 3 Ohm (green) dual fire coils I am testing. What I would like to know is: What is the ideal dwell (~12 V) for these coils? Any advice appreciated.

I received this response:

Dear Mr. Ragle,

Thank you for your interest in Dynatek ignitions. We would recommend a dwell time of 8-10ms for the 3 ohm coils and 10-12ms for the 5 ohm coils. If we can be of any future assistance please feel free to contact us anytime.

Regards,

Technical Support
Toll Free: 800-928-3962

Re: The VeeCU

Posted: Wed Dec 06, 2023 6:04 am

by WesRagle

HI Guys,

After spending time on other projects, I find myself with some slack time. I’ve been using the spare time to advance the VeeCU project. I wired the evaluation board for the CPU and the MC33810 “Automotive Engine Control IC” together to make sure the IC performed as advertised. Everything worked fine, including being able to shut down the coils without a spark (soft shutdown). I felt I needed that so I could allow for prop start and still shut down the coils (after a 10 second delay) without a puff, pop, or fire. Don’t want to make a dangerous task even more dangerous.

For those interested, the CPU will be an STM32L476RGT3 and the Engine Control IC will be an MCZ33810EKR2.

IMHO, for this to be a viable solution for VW efi, power/current consumption has to be controlled. Especially at idle.
Toward that end, the dwell time for the ignition coils has to be controlled.

I tested both the 5 Ohm and the 3 Ohm coils. Both had similar spark duration and fired down to about 5-6 volts with a 12 mSec dwell (see previous post). I had no way of measuring spark current but I assume the 3 Ohm coil has a “hotter” spark. I did a rough measurement of the ignition current at 1000 RPM and 12 mSec dwell. It was below 1 amp for 3 Ohm and about 1/2 amp for the 5 Ohm.

Other than the fuel injectors, which shouldn’t draw much current at idle and not more than 3 amps at WOT, the other high power device is the fuel pump. I wore Google out looking for a good candidate. After days of searching it occurred to me to search for “motorcycle fuel injector pumps”. One popped up that looks like it’s in the sweet spot for this application. Name brand, proper size, and readily available. Walbro GSL414.

Ref. https://jdtracing.com/products/walbro-gsl414-external-fuel-pump-for-1999-2001-victory-v92c-v92sc

So, about 3 amps for the pump, 1 amp for the ignition, and less than one amp for the injectors and you’re at less than 5 amps for an EFII system at Idle. That’s much less than the stock secondary ignition with 3 Ohm coils that I currently run on the Hummel.

Wes

Re: The VeeCU (Finding Injectors)

Posted: Sun Dec 10, 2023 10:44 am

by WesRagle

Hi Guys,

Another problem you run into while considering fuel injection is finding injectors with the proper flow rate, impedance, form factor, …

For a four cylinder engine generating about 80 HP, the automobile market isn’t a lot of help. I finally found a web site that gives you most of the information you need, allowing you to search by flow rate, form factor, etc.

Ref. https://www.injectorplanet.com/

This one for a Polaris Rzr might be about right.

Ref. https://www.injectorplanet.com/products/bosch-0280156208-polaris-1202863

Wes

Re: The VeeCU

Posted: Mon Dec 11, 2023 6:15 pm

by lakespookie

I would order from digikey for any component/electronics needs you will have all the details and country of origin but no free shipping.

Re: The VeeCU

Posted: Tue Dec 12, 2023 7:59 am

by WesRagle

lakespookie wrote:I would order from digikey for any component/electronics needs you will have all the details and country of origin but no free shipping.

I would but Mouser’s global headquarters and distribution center is one county east of me and UPS Ground arrives next day.

Wes

ArchiveBot · May 23, 2021, 5:03am

Re: The VeeCU

Posted: Tue Dec 12, 2023 8:32 am

by Dave Wolfe

Wes,

For the injectors, if you pick injectors with lower flow rates, the required current goes up. SDS indicates their system works good if you keep the minimum idle injector pulse width above 1.5 ms. With that, I get a maximum injector flow rate of 200 pph. The minimum flow rate I calculated at 14pph.

Heres what I calculated for injector current vs flow rate:

Inj Size / Duty cycle and amps
15 pph = .75. tot amps 3
20 pph .5. Tot amps 2
50 pph = .2 tot amps .8

Re: The VeeCU

Posted: Tue Dec 12, 2023 12:20 pm

by WesRagle

Hi Dave,

I understand your point.

I am attempting to do everything “According to Hoyle”. I will attempt to properly characterize the fuel injectors so that a good tune will not be affected by changing injectors. The attributes I worry about are the injector offset (open time - close time), the offset as as a function of voltage, and the non-linear section of the injector flow at low pulse width. The only thing I won’t attempt to characterize is the small non-linear section of the curve.

If you take a look at this document it illustrates the above attributes of a randomly selected fuel injector.
https://cdn.shopify.com/s/files/1/0414/1681/8852/files/02J-XX-1000-X_Injector_Characterization_Summary.pdf?v=1618867983

Since those attributes are a little harder to model (may not be exact) than the static flow rate, it would be good to keep them as small a percentage of the total overall pulse width calculation as practical. To do that I want the smallest fuel injector possible (largest pulse width), without violating any other constraint.

For my particular situation, using Ross’s number of .55 lb /hp/hr:

85 hp * 0.55 = 46.75 lb/hr.

To keep the duty cycle down to 75%.

46.75/0.75 = 62.33 lb/hr.

Since the mixture knob will allow you to dial in up to 1.5 times that amount, the flow goes to:

1.5 * 62.33 = 93.5 pph.

So, the minimum flow rate for each injector is:

93.5/4 = 23.375 pph.

Again, using 0.55 lb/hp/hr, at a typical cruise of maybe 50 HP you get 50 * 0.55 or 27.5 pph total or 6.875 pph/injector.

6.875/23.375 gives a duty cycle of 0.3 in cruise. Assuming 1 amp per injector that gives ~ 1.2 Amps total cruise current.

The injectors I will begin with have a static flow rate of 190 grams/min = 25.1327 pounds per hour.
Ref:https://www.aliexpress.us/item/2251832106098404.html?spm=a2g0o.detail.1000060.3.36792e41mrUtk7&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.291025.0&scm_id=1007.13339.291025.0&scm-url=1007.13339.291025.0&pvid=52b0053d-5f15-4459-a60e-dd1973f36c8a&_t=gps-id%3ApcDetailBottomMoreThisSeller%2Cscm-url%3A1007.13339.291025.0%2Cpvid%3A52b0053d-5f15-4459-a60e-dd1973f36c8a%2Ctpp_buckets%3A668%232846%238114%231999&pdp_ext_f=%7B%22sku_id%22%3A%2264409778182%22%2C%22sceneId%22%3A%223339%22%7D&pdp_npi=2%40dis%21USD%2134.0%2132.3%21%21%21%21%21%402103222216720226395406415e5e48%2164409778182%21rec&gatewayAdapt=glo2usa

Are you running SDS EFI?

Wes

Re: The VeeCU

Posted: Tue Dec 12, 2023 1:49 pm

by Dave Wolfe

SDS is my plan. Thats a long way off at this point… Need to build wings, then tackle the engine.

Your project is looking good! Keep up with the updates.

Re: The VeeCU

Posted: Wed Dec 13, 2023 9:59 am

by WesRagle

Hi Dave,

Thanks for the encouragement.

I’ve spent the last month or so working on the hardware design. The schematic, a series of eight and a half by 11 sketches and parts lists, has been been delivered to a PCB designer. He’s backed up until after Christmas. Once he gets freed up I can get a good schematic and a 3D model of the unit.

For now, I’m back on software. Until now I’ve been focused on signal acquisition and proper pulse generation (phasing and duration). I haven’t concerned myself much with fuel and spark maps. So, that’s the focus now. Fuel maps, spark maps, warm up enrichment, …

Example of details being worked out.

Do I want to apply a one time primer pulse when I see the first blade after power is applied?
If so, how big a pulse. What are the units of a primer pulse? Can’t be mSec. That would make it injector specific. Maybe a number of “cylinder fills (A/F = 14.6)” on a standard day at sea level. What is the valid range of a primer pulse? I don’t know maybe 0 to 5.

Anyway, you catch my drift. I’m working on all the details that make up an engine tune.

I have all the signal inputs of the breadboard hooked up to potentiometer so I can test code on the bench as I go.

Wes

Re: The VeeCU

Posted: Wed Dec 13, 2023 5:41 pm

by BRS

The SDS Primer pulse is part of their accelerator pump (one in the same). With the pumps on just moving the throttle from idle to about 1/2 throttle give a little pulse through the injectors. So, for starting (in my case on an IO-360) I just need to pump the throttle three times and then hit the starter button. If it does not catch right away I do one more pump while starter is engaged. Would this work in your case?

Re: The VeeCU

Posted: Wed Dec 13, 2023 7:01 pm

by WesRagle

Hey Brock,

No, no TPS. I’m focused like a laser on VW conversions with slide carbs. I didn’t want to worry with trying to mount some kind of linear displacement pot.

I do intend to implement an accelerator pump function. The peripherals on the MPU really scream. All calculations will be based on the running average of the each parameter during the most recent two engine revolutions. That will be somewhere in the neighborhood of 100 to 200 samples at WOT.

All that to say that I will try using the time rate of change of MAP instead of throttle position to implement the accelerator pump.

As a side note, originally accelerator pumps were implemented in carbs (also in throttle body injection) to replenish the lost fuel on a wetted intake under rapid acceleration. If the data acquisition is responsive enough, port fuel injection shouldn’t need much of an accelerator pump. All of this from books. I’ll have to verify it. That’s part of the fun

Wes

Re: The VeeCU

Posted: Thu Dec 21, 2023 5:17 pm

by WesRagle

Hi Guys,

The list is a little slow today so I’ll jabber some.

For those interested in EFI:

The genesis for the VeeCU was the podcast : http://www.sonexflight.com/58/index.html . It’s very interesting and informative. Highly recommended. It got me fired up

When I first started down this road I bought any and every book I thought was relevant to EFI.

Some of them are useless, some are OK, and one is excellent.

If you are interested in EFI I highly recommend this book.

The author is an OEM tuner by day and a performance tuner by night. An easy read and mixes theory and practice of engine tuning nicely.

As for the VeeCU project, I’ve been working on memory layout. I’m keeping things as simple as possible. As of right now here is what an engine tune will look like. It won’t format right when posted, but you get the idea.

eTuneTypeDef eTuneType; // Version of the tune template.
char cTuneName[80]; // The name ex. “High Compression Hummel 2400”.

uint16_t u16TotDisplacement; // Total displacement in cc.
uint16_t u16ComRatio; // Compression ratio * 100.
bool bIsTurboed; // True if turbo charged.
uint8_t u8AltPPR; // Alternator pulses per revolution.

int16_t as16RPM [RPM_POINTS]; // RPM break points for the VE and Spark tables.
int16_t as16Spark [RPM_POINTS]; // Ignition advance at RPM points.
int16_t as16VE [RPM_POINTS]; // Volumetric efficiency at RPM points.

int16_t as16EngTemp [TEMP_POINTS]; // Temp break points for warm up enrichment.
int16_t as16CSEnrich [TEMP_POINTS]; // Enrichment Pcnt. * 10 for warm up enrichment.

int16_t s16Cyl1Trim; // Percent * 10 Trim for cylinder 1.
int16_t s16Cyl2Trim; // Percent * 10 Trim for cylinder 2.
int16_t s16Cyl3Trim; // Percent * 10 Trim for cylinder 3.
int16_t s16Cyl4Trim; // Percent * 10 Trim for cylinder 4.

uint16_t u16FuelPressure; // Fuel Pressure regulator in mBar.
uint16_t u16FuelCutRpm; // RPM for over speed fuel cut.

uint8_t u8PrimerSize; // # of cyl fills for primer pulse.
uint16_t u16APSens; // Sensitivity of Accel Pump.

The unit can store any number of tunes.

For you C afficionados, anything I forgot?

Oh yea, I spoke with Peter Van Schalkwyk and he said he didn’t have a throttle position sensor on his second SDS EFI VW aircraft and he didn’t notice any difference with out the accelerator pump function. For starting, he said if the engine didn’t fire immediately he would use the mixture knob to add more fuel.

Wes.

Re: The VeeCU

Posted: Mon Jan 29, 2024 2:53 pm

by WesRagle

HI Guys,

Here is a link to a web site that actually provides some specifications for the sensors they sell.

Ref. https://www.bmotorsports.com/shop/index.php/cPath/129?osCsid=p2r9p1f7qf76k3afa1vuislj27.

In the interest of long term availability and universal applicability, I’ve decided to go with this 2 bar sensor.

Ref. https://www.bmotorsports.com/shop/product_info.php/cPath/129_143/products_id/1582?osCsid=p2r9p1f7qf76k3afa1vuislj27

Wes

Re: The VeeCU

Posted: Tue Jan 30, 2024 5:59 pm

by WesRagle

Hi Guys,

The PCB designer on this project has generated a preliminary schematic of the VeeCU and has estimated the required board area. I can now proceed with enclosure selection.

The unit is being designed for mounting on the engine side of the firewall. That requires that the unit be semi-sealed. To keep cost down a commercial off the shelf (COTS) enclosure and cable system will be used. See attached. It looks like the enclosure, connector, and mating connectors will add about $100 to the Bill of Materials. As a side note, I found a “Hydro-Phobic” patch to keep fluids from entering the vent hole.

https://www.interstatesp.com/products/vents/.

Right now I’m defining the Pin-Out. I want to design the simplest, from a users point of view, Speed-Density EFII system possible. Toward that end I would like the unit to be usable without an intelligent control head. I do have a CAN bus and an RS232 interface which will allow for tuning via a laptop or an intelligent control head in the future, but for now I would like to “Keep it simple”.

So the question is: “What is the minimum interface required for operation?”.

I envision:

A mixture knob.
Four SPDT Center off momentary switches for cylinder trim.
A single red LED to report system status.
Maybe a Store switch to make trim changes “permanent”.

I could use a POT with an OFF switch, similar to a volume knob, which would allow the user to turn the injectors off as part of the shut down procedure. Or I could just let the installer wire the injector power on a separate switch if that function was desired.

Does that sound reasonable? What am I forgetting? Any thoughts?

Thanks,

Wes

Re: The VeeCU

Posted: Sat Feb 24, 2024 11:30 pm

by WesRagle

Hi Guys,

I’ve gotten some more time in on this project.

As a side note, when I started looking at fuel injection systems I was intimidated. So, when I started down the path of building my own ECU my vision was to produce a simple to use and simple to understand system. It’s normal while designing such a device to dream/muse about solving all problems of all engines. However, if you go down that path you will never finish. So, the VeeCU is being designed to work only on VW’s with Open Collector/Open Drain secondary ignition systems like the Dyna S ignition on my Hummel, and I assume like the secondary ignition on the AeroVee . I also want the unit to be simple to install. So, the existing ignition system components are used for both spark and timing. The only sensors used are MAP, Engine Temp (for warm up enrichment), and inlet air temperature. That’s about $100 in sensors.

Having said that, some of the following will make more sense.

I’ve laid out the memory in such a way as to future proof the design as much as possible. The MCU has tons of FLASH (non-volatile) memory. Some of the memory will be used to store a data base of known good tunes. The vision is that as the VW fliers generate good tunes, those tunes will become a permanent part of the VeeCU program. There will also be a data base of tested/verified injectors. So, an initial tune will consist of selecting the tune of an engine similar to/exactly like yours and picking from the approved injector list. We’ll see.

It may seem odd, but implementing the tune is close to the final step in the software development process. There is a lot of head scratching that comes first. I’ve finally gotten around to implementing the tune.

To use the VeeCU, the secondary ignition is retarded to 3 Deg AFTER top dead center. The secondary ignition output is routed to the VeeCU used as a timing pulse. An output of the VCU is routed to the ignition coils and provides spark control. Right now I am simulating the timing pulses with a signal generator. The positive edge is assumed to be the forward ignition and the negative edge is assumed to be the aft ignition pulse.

As it turns out, starting the engine is the more difficult part to get right. Here is a pic of the forward signals as the signal generator is sweeping from 1 Hz (60 RPM) to 15 Hz (900 RPM) in one second, simulating a start. The yellow trace is the timing pulses The light blue trace is the ignition signal. The coil fires on the falling edge of that signal. As shown, while the engine is cranking (RPM < 450) the system acts as an impulse mag. That is the spark fires when the timing pulse hits, 3 deg. ATDC. As the engine moves from cranking to starting, timing is taken from the table in the tune. One of the few serendipitious things is that changing the idle state of the ignition timer output from high (for impulse) to low (for dwell control) causes the coil to fire. So, I don’t have to do anything hokey to get the last TDC fire before changing to timing/dwell control. You can also see where the initial dwell is much longer than the final dwell. That’s because the engine will try to “run over” the timing pulse as it accelerates rapidly from starting to run. Worst case, if the engine starts very fast, the effect will be timing is retarded to TDC. As the engine reaches steady idle the dwell is further reduced to the 12 mSec recommended by Dyna Tec.

The dark blue trace shows the injector pulses. If you look closely you can see the phase changes as the engine accelerates to run. That’s because during cranking and starting the pulse is phased to hit an open intake valve (half the time, remember wasted spark/semi-sequential). Everything I’ve read says to aim at a closed valve during run. That will allow the fuel to fully vaporize/evaporate against a hot valve and hopefully provide better cylinder head cooling by evaporating a gallon of fuel per hour on each head.

Here is a pic generated by powering on the VeeCu while the input signal is at 15 Hz (900 RPM). The yellow trace is the timing pulses. The light blue line is the ignition pulses. The magenta trace is fuel injection pulses. The dark blue line is /OE. No output will be delivered to the coils or injectors if /OE is high. /OE will not be driven low until two blades are seen. It’s just to insure that the ignition coils aren’t energized if the prop happens to stop right at the edge of one of the hall effect sensors. Another nuance is that fuel will not be injected unless a pulse has been seen on the “other” coil since last time fuel was injected by “this” coil. The first ignition pulse is generated as if the engine was cranking. That’s because it takes two pulses to calculate an RPM so it can be determined that the engine is running.

You can also see where the first two injector pulses are wider than the others. That is the primer fuel being added to the calculated fuel quantity. The primer pulse(s) are calculated by multiplying the pulse width of the normal fuel pulse by two. Again you see two due to wasted spark. Calculating prime this way naturally causes the primer amount to increase due to “warm up enrichment”, low OAT, and rich mixture setting. The two double wide pulses are the result of one (1) being set as the prime value in the tune. If two was set you would see four double wide pulses.

And lastly, a pic of me cruising at 3000 RPM with all input parameters pretty much normal
The first injector in the data base is the one I selected for my plane. As can be seen, the injector duty cycle is right at 20% in cruise. The only way to saturate the injector is to fly at red line with very cold cylinder heads, very cold IAT, and the mixture set full rich. While looking at the yellow timing trace, roughly speaking, the top part of the trace is while the piston is going down and the bottom part of the trace is while the piston is moving up. You can see that the injection pulses occur while the piston is moving up during both the exhaust and compression stroke, so the intake valve is closed during the injection. You can also see that the ignition is advanced 26 Deg (based on the tune). One last thing, you can see the constant 12 mSec dwell.

All of the injection and ignition pulses are hitting within 10 micro-seconds of target. That’s within 0.2 angular deg at red line. I do have one more somewhat big thing left to implement. Since our alternator is fixed to the crank it can be used as a timing source in the event of timing signal lost from the Dyna S. The phase relation will be determined after the engine is in run state. I’ve already done this once but it got too ugly. I now understand how to implement the feature with minimal impact on the remainder of the software.

Forever Forward,

Wes

Re: The VeeCU

Posted: Sun Feb 25, 2024 10:10 pm

by WesRagle

Hi Guys,

Just implemented the rev limiter. This pic shows the /OE (Output Enable Bar) disabling spark and fuel. /OE is the bottom trace. Outputs are disabled while /OE is high. The rev limit comes from the tune. For the Hummel, published red line of 3600 RPM, I’ll set the rev limit to 3800. The hysteresis if fixed at 100 RPM. So, once the outputs have been disabled they will not be re-enabled until the RPM drops 100 RPM.

This pic was generated by sweeping the input up and down across the limit and repeating every 0.2 Sec. The limiter runs asynchronously to the trigger pulses. But, since the engine control IC performs soft shutdown of the ignition, no harm no foul. This is a harsh way to rev limit. It would be much kinder to limit RPM by retarding the timing. However there is probably a fixed primary ignition running so that won’t work.

Wes

Re: The VeeCU

Posted: Mon Feb 26, 2024 10:37 pm

by WesRagle

HI Guys,

My “Pic of the day”

This pic shows individual cylinder trim on all 4 cylinders. I manipulated the inputs so that the untrimmed duty cycle of the injector pulses was 50%. The injectors are “ON” while the signals are high.

I pared the injectors for the front two cylinders on the top two traces. The bottom two traces are the aft cylinders. In operation the trim will be limited to ± 20.0 % but I killed the limit while testing. The first trace shows a cylinder trimmed to 0.0%. The second trace shows that cylinders mate cylinder trimmed to +50.0%. The third trace shows the first cylinders of the other pair trimmed to 0.0%. The forth trace shows it’s mate trimmed to -50.0%. I don’t have enough inputs on the scope to show the phase relation of the injector pulses to the timing pulses, but the pulses are all timed to end at the same phase BTDC. And of course trace #1 and #3 are 180 deg out of phase.

If the pic is clear enough to see the grids on the scope screen, you will be able to tell that the second trace is just shy of 1.5 x the length of the first trace. That is because the injector offset (open time - close time) is only applied once.

I also applied limits to all of the inputs, in part to detect sensor faults. Of course the sensor that worries me the most is the MAP sensor. That got me to thinking (maybe too much), …

What if when the MAP sensor fails, instead of defaulting to a set value, I calculate a value based on RPM? If there was a small table that correlated MAP to RPM near ground level where ever you fly most, that would eliminate a lot of my concern about the MAP sensor failing during takeoff or landing. If the sensor happened to fail at high altitude, the panel light would indicate the sensor had failed and the mixture knob could be used to lean things back out. You would then have to walk the airplane back down by adding fuel with the mixture knob as you descend. Of course this would only work with a fixed pitch prop. Hmmm…

I have to get back on the hardware now. I need to do a final, thorough review of the schematic before PCB layout begins. There are currently two non FI/IGNITION outputs. One for simulated FF and one to de-energize the fuel pump relay if the RPM transits from run to stopped very quickly. I’m thinking of adding an RPM output, just for convenience.

Thanks,

Wes

Re: The VeeCU

Posted: Wed Feb 28, 2024 7:00 pm

by WesRagle

Hi Guys,

I had an interesting experience yesterday.

For software development I have everything mocked up in the “office”, including a 5 Ohm Coil and a 3 Ohm coil with spark plugs connected.

On a whim I decided to see what happened if I disconnected one of the plug wires at the coil.

I disconnected from the 5 Ohm first and ran the system. The plug that was connected continued to fire but the spark looked a little weaker, orange instead of blue.

Then I disconnected the a plug from the 3 Ohm coil and ran the system. Holly crap!!! It sounded like the cannon on the front of an A10 only angrier!!! My computer screen went black so I couldn’t hit the pause button. Next was me dancing around trying to remember which switch to turn off.

Since inquiring minds want to know, I contacted Dynatek tech support.

Long story short, there is only one secondary winding on Dynatek dual plug coils. Both plugs are in series with the secondary winding. This insures that the plugs fire simultaneously. The 3 Ohm coil stored enough energy to cause an internal arc, maybe to the core. In any event, the advice from tech support is “The internal arcing is not healthy for the coil though so should be avoided altogether.”.

Why the 5 Ohm coil continued to fire on the connected plug (without the audible arc) is still a mystery.

Wes

Re: The VeeCU

Posted: Wed Feb 28, 2024 8:59 pm

by BRS

Well that sounds exciting. Too bad you didn’t have the whole thing on video.

Re: The VeeCU

Posted: Thu Feb 29, 2024 9:45 am

by WesRagle

Yep, it would have made it on America’s Funniest Home Videos

Wes

Re: The VeeCU

Posted: Wed Mar 20, 2024 5:05 pm

by WesRagle

HI Guys,

I’ve been hammering on the VeeCU. Here is a trace of a normal engine start.

Since I don’t have hardware yet, the bread board is programmed to accept rising edges of the top trace as the front secondary ignition inputs and the falling edges as rear cylinder secondary ignition input. It’s just an easy way to get pulses 180 degrees out of phase with a single input.

So, …
The yellow trace is/are the secondary ignition inputs which will be robbed from the secondary ignition coils.
The light blue trace is voltage to the secondary ignition coils. It replaces the inputs I stole
The magenta trace is the output enable pin. While low the engine control IC outputs are enabled.
The dark blue trace is the injector pulses going to the right front cylinder.

For safety reasons, I don’t allow any ignition or injector pulses until both the front and rear secondary ignition pulses have been seen during the most recent 10 seconds.

So the sequence goes like this:

The first falling edge of the top trace signals that the rear secondary ignition pulse was seen.

Then, when the rising edge is seen, both forward and rear have been seen withing 10 seconds and the outputs are enabled as seen on the magenta trace.

As soon as the outputs are enabled, since this is the first start since power up, a primer pulse is applied to all cylinders. This can be seen by the “wide” first pulse on the dark blue trace. This is a one time thing per power cycle unless the prime is manually rearmed.

On subsequent rising edges you can see the ignition pulses on the light blue trace. The pulses are initially in “impulse mode” behaving much like the secondary always has except the secondary has been retarded to 3 Deg. after TDC, hence like an impulse mag. As the engine passes from “Cranking” to “Starting” the ignition switches to Dwell control and pulls the ignition advance from the “Engine Tune”. As the engine passes from “Starting to Running” the Dwell time is further reduced to 12 mSec as per Dyna Tec’s advice.

So, it takes a minimum of three blades to fire the engine.

A lot of words for a simple pic

One more scope pic. This pic turns off all but the secondary ignition pulses and the injector pulses. During the early starting phase the pulses are “aimed” at the center of the down stroke. Since this is a “semi-sequential/staged sequential” system every other pulse hits an open intake valve. The other will hit half way down the power stroke. As the engine speeds up the injection pulses are timed to end just before TDC.

I implemented the reversionary mode and it works great on the bench. Right after engine start, a stability check begins. Once the engine is stable, the phase relation of the alternator pulses to the input secondary ignition pulses is calculated. If during engine run the secondary ignition pulses go away (for a heart stopping 1/2 sec), or has 10 percent missing pulses, the alternator takes over to drive ignition and injection. All of this is reported by the only means I currently have, winks and blinks of the panel LED.

I couldn’t resist buying a copy of the enclosure for motivation. I like it. Every VeeCU electronic component is extended temp range. I intend to install the unit forward of the firewall. This enclosure is just about perfect for that purpose.

Just the right size. The right number of pins. Optional ferrites on all pins. Optional vent with “hydrophobic” membrane. Very tight/nice seal. Very affordable with sealed mating connectors.

Anyway, if you can’t tell, I’m get’n stoked. The user interface (i.e. switch reads and de-bounce, LED flash patterns etc. …) is as far as I can go on the bread board. Software is just about ready to hook up to a real engine for “FMEA”. It’s gonna be fun The schematic is complete and layout is under way.

The Design Engineer did this just to get an idea of how crowded, or not, the board will be. Not all components dragged on yet, most notably the IGBTs for ignitiion drive, but it’s not going to be bad.

Forever Forward,

Wes

ArchiveBot · May 23, 2021, 5:03am

Re: The VeeCU(Plugs & Coils)

Posted: Mon Mar 25, 2024 10:13 pm

by WesRagle

HI Guys,

While I’m set up to test coils and plugs I had to go ahead and compare the 3 Ohm Coils and the 5 Ohm coils. The VeeCU monitors the output of the 5V pre-regulator which feeds the 3.3 V regulator which provides CPU power. When the 5V regulator drops out of regulation the system resets. The 5V regulator is low drop out so the VeeCU will reset at about 6 volts. So, I wanted to know if the plugs would still be firing at 6 V, at least in air. I had read where Brock and others were using, or switching to, iridium plugs so I tested those as well to see if I got a little better/longer spark.

Here are the results (same plug gap):

3 Ohm Coil @ 13V with standard plugs (removed at last annual).

3 Ohm Coil @ 13V with iridium plugs.

3 Ohm Coil @ 6V with standard plugs.

3 Ohm Coil @ 6V with iridium plugs.

=========================================================================

5 Ohm Coil @ 13V with standard plugs.

5 Ohm Coil @ 13V with iridium plugs.

5 Ohm Coil @ 6V with standard plugs.

5 Ohm Coil @ 6V with iridium plugs.

Not a lot of difference in the spark between normal and iridium plugs. Of course the iridium spark didn’t dance around in the gap like the normal spark does. Both the “regular” and iridium plugs were miss-firing on the 5 Ohm coil at 6 volts. I just happened to catch a worse spark on the iridium plug.

The 3 Ohm coil was still firing nicely down to 6 volts.

Under normal operating conditions (13 V) the 3 Ohm coil produced a 2.5 mSec spark while the 5 Ohm produced a 1.5 mSec spark. Exactly the ratio you would expect.

BTW, the tests were done with 12 mSec dwell. I took a brief look at the sparks with longer dwell times and it didn’t make a noticeable difference.

Anyway, I’m still on the fence on whether to switch to 5 Ohm coils or not.

We’ll See,

Wes

Re: The VeeCU

Posted: Tue Mar 26, 2024 4:50 pm

by WesRagle

HI Guys,

I’ve been re-running some power dissipation numbers and wanted to know what normal power dissipation will be. It dawned on me that I should just measure the current through the coils instead of using calculated numbers.

I was told by Dynatek Tech Support that the max recommended dwell for the 5 Ohm coil is 12 mSec., 10 mSec for the 3 Ohm coils. I’m going to set 12 mSec as the standard Dwell so I can use whatever coil I like.

Here are some measurements taken at 13 V power:

During start each 3 Ohm coil draws just about 3.5 Amps (No dwell control).

@ 15 Hz (900 RPM) each 3 Ohm coil draws 0.4 Amps.
@ 65 Hz (3900 RPM) each 3 Ohm coil draws 1.8 Amps.

With dwell control the current increases linearly with RPM.

If I mentally rewind to when I decided I had to control dwell, it was so I could get the entire EFI system current to below what my present secondary ignition draws at Idle.

With 3 Ohm coils, dwell at 12 mSec., and using a Walbro GSL414 fuel pump, at idle I’m down to:

2 x 0.4 Amps for ignition
3 Amps for the fuel pump.
Less than a 1 Amp for injection.
Way less than 1 amp for the ECU.

Less than 5 amps total for the entire system.

That’s less than my present secondary ignition system draws at idle.

So, I’m going to quit worrying about which coils to use and just keep my 3 Ohm coils. Besides, I have a 35 amp alternator to pump the battery back up

Wes

Re: The VeeCU

Posted: Tue May 07, 2024 2:59 pm

by WesRagle

Hi Guys,

Some progress on this project. I bought a couple of CAN (Controller Area Network) interface adapters and interfaced a display board to the “bread board”. The buss is running at 1/2 speed, 500 KHz. To keep the software neat, I overlaid an ARINC 825 API over the CAN bus. The API allows for “peer to peer” and “broad cast” messaging over various channels (Exception Event Channel, Normal Operation Channel, …). Of course this took longer than it should have, but for me it was worth the effort.

The display board is an STM32F746G-DISCO and will be used for initial “live” testing.

Ref: https://www.mouser.com/ProductDetail/STMicroelectronics/STM32F746G-DISCO?qs=KuGPmAKtFKV4xEByQ7IKqA%3D%3D&mgh=1&utm_id=17222215321&gad_source=1&gclid=CjwKCAjwouexBhAuEiwAtW_Zx7HBJxDnTAglweFiJR2stzzQUsqL_RWEvyj4-BgnDtVWhdX4W-IcGhoCiZQQAvD_BwE

All of the analog signals are being input with POTs. The pulsed signals are being input with a signal generator.

There will be some minor adjustments needed when I receive the actual hardware. I will have to change the sensor definitions from POTs to the actual sensors and adjust the clock initialization for the crystal used. And, I almost forgot, the switch read routine. Other than that I’m set. I can force execution of every line of code. I can polish the software to my hearts content.

Wes

Re: The VeeCU

Posted: Tue May 07, 2024 4:13 pm

by WaiexB22

I’m late to the party, but I have been trying to read along and catch up on your project. I just wanted to let you know I have enjoyed reading through your posts and I am impressed by your experimenting and your results thus far. Keep it up!

Re: The VeeCU

Posted: Tue May 07, 2024 10:37 pm

by WesRagle

Hi Robert,

Thanks for the encouragement. And I’ve been watching your engine installation. Exciting stuff!! I wish I could weld

Me, I can’t wait to hook up to an actual engine. It’s going to be a lot of fun.

Wes

Re: The VeeCU

Posted: Thu May 09, 2024 8:16 am

by WesRagle

Hi Guys,

I’m getting close to the finish line of implementing the software of the VeeCU. I’d like to bounce some ideas off you guys.

A little background. Listening to Jeff’s pod cast on SDS EFI is what sent me off on this adventure.
Ref.: http://www.sonexflight.com/58/index.html

I wanted to implement an EFI system with the AeroInjector as a backup. I started studying the available solutions and,
since I knew nothing about fuel injection, I was somewhat intimidated. So I started studying EFI and envisioning what I wanted. What kept popping into my head was simple. I want it to be safe and simple.

Here is what I came up with: As currently designed the cockpit interface to the VeeCU consists of four miniature momentary SPDT toggle switches for cylinder fuel trim. A store push button to transfer user settings and fault codes to non-volatile memory. A potentiometer to adjust mixture setting. And finally a status LED to indicate operating status. That’s it.

User settings consist of:

Fuel Flow Trim (%) used to make fine adjustments to the simulated Red Cube output.

Four cylinder trim (%) [-15.0 to 15.0] used to balance fuel flow between cylinders.

Prime Strength [0-5] is a multiplier for the first injection pulse during engine start to prime the engine.

Accelerator pump sensitivity (mBar). Wanting to keep the number of sensors to a minimum, I don’t want to add a Throttle Position Sensor. Instead, manifold pressure change is used to sense increased load and the need for a little extra fuel. The Accelerator pump sensitivity is a threshold below which a MAP change will not trigger any extra fuel.

Accelerator pump gain [0-5]. A scaler for How much fuel to add during an accelerator pump event.

A set of fault codes. Any fault code, even if it clears, that occurred during the last flight is retained and displayed again at engine shutdown. Since all that is available is a LED to flash codes, a press of the store button saves the codes in non volatile memory so the pilot can shut down and go find the list of codes to see what happened. All user data is retrieved when the unit is powered again. The codes are then stepped through/cleared by toggling one of the trim switches with the engine shut down. Another press of the store button will permanently clear the codes. A bit of a pain but it eliminates the cost and complexity of a display. BTW, No changes are made permanent without a press of the store button.

So what do you guys think? Am I crazy? Do you have to have a display to have fuel injection? There isn’t one in my pickup

And here’s a decision that I’ve been postponing. One of the aux outputs is intended to drive a fuel pump relay. The intent is to disable the fuel pump in the event of a mishap. Exactly what logic should be used to disable the pump. One thought is to enable the relay at power up and disable it after RPM has been above maybe 2400 and then returns to zero. I’m open to suggestions.

Edit: BTW, here is what Ross from SDS has to say about it in his EM5 manual.

Optional Fuel Pump Relay
SDS units can be equipped with an optional output to control a relay to switch the fuel pump off when the engine
is not turning over. This feature is designed to prevent the pump from emptying the tank in a serious accident.
The pump relay is energized for 2.8 seconds when power is turned on to pressurize the fuel rail until the EM-5
detects crank rotation. If the engine stalls the EM-5 will shut off the relay in 2.8 seconds. There is nothing
programmable for the fuel pump relay.

Re: The VeeCU

Posted: Thu May 09, 2024 10:30 am

by BRS

Wes,

Your progress is exciting and I’m looking forward to the completion. What an improvement this would make to these VW engines.

As an SDS advocate (used on 3 different aircraft) I’ll give me 2 cents. I don’t think a display is needed at all. On one of my aircraft after the intial setup I completely removed the SDS programmer/display head. Setup is always, even with the SDS display, something that takes patience and plenty of reference to documentation. If it’s done via toggle switches and indicator light, that’s fine as long as documentation is clear. From your description above it was hard to envision what you were doing. Look forward to seeing it in a video.

On the fuel pump relay. I used this feature on one of the three installations I’ve flown. It was nice that I could turn the key to ‘on’ and the pump(s) would pressurize then cut off. This greatly reduced the battery draw before I would start the engine in case there was a delay in getting going. With the sonex airframe the fuel shutoff is something that most pilots are very used to using since the AeroInjector (and others) can siphon. So for an engine failure of some sort where the pilot has time to prepare for a forced landing the relay is not needed. On the otherhand if there were a botched landing or takeoff excursion then this feature would be helpful. My only hesitation with this relay is that it introduces another potential failure point. In the case of SDS it is an option the builder can use or not. Seems like a good policy to me.

Are you proposing two fuel pumps and would they both go through the relay or each have their own relay or only one wired through the relay?

Re: The VeeCU

Posted: Thu May 09, 2024 5:17 pm

by WesRagle

Hi Brock,

Thanks a lot for the reply.

From your description above it was hard to envision what you were doing. Look forward to seeing it in a video.

I’ve never made a video before but I will give it a shot once I have an engine up and running. I’ve already borrowed a camera from my daughter and will learn how to use it. It is hard to describe how things work without pictures, but here goes.

The evaluation board that is standing in for the VeeCU has a spare LED so I’ve been able to program that to act as the panel LED.

For the moment assume that the tune has already been done and you are sitting in the cockpit getting ready to fly. When you power up the ECU this is what you will see: The LED will illuminate steady (assuming that all sensors are in expected range). The LED will initially act as a simple pilot light indicating power on status. Once the engine has started, the LED will flash a specific sequence a couple of times to indicate that the ECU is locking on the the alternator pulses so they can serve as a backup to the secondary ignition pulses in the event of a secondary ignition module failure. Once the phase of the alternator pulses are determined, the LED will flash at a 50% duty cycle, once per second, until the engine completes warm up (presently set at 60 Deg. C CHT). At that point, the LED extinguishes and will remain off (again assuming no faults are present) until the engine exits the “Running” state/stops.

Once the engine is running, the toggle switches can be used to trim the individual cylinder fueling. The panel LED flashes on for 1/10 of a second each time a trim switch is activated to acknowledge the action. Presently the switch adds or subtracts 0.5 % fuel for each activation. If the switch is held on for one second the switch will begin to repeat every 300 mSec. If the trim is driven to the +/- 15.0% limit, the LED will flash on for a full second each switch activation to let you know you are at the end of the range. If you are happy with the trim, a press of the store button will make the change permanent.

The only problem I see with this is getting too far off center and hitting the trim stops. With no display you can’t tell how close you are to the stops. I’m hoping that can be handled by using a specific trim procedure. That is, trimming two cylinders up and two cylinders down to achieve balance. Anyway, I know, a video

As for the fuel pump relay, I’ve never checked whether or not the Walbro fuel pump leak back through the pump while the pump is off. If not, the method Ross uses is perfect. Left to my own devices I would have already done it the way that I mentioned earlier except I suspect a violent upset might cause a momentary power interruption causing the pumps to reactivate.

So, do the Walbros have a check valve or otherwise not allow backward fuel flow?

Are you proposing two fuel pumps and would they both go through the relay or each have their own relay or only one wired through the relay?

I’ll start with one pump. Take off and landings will be done using the AeroInjector. As far as wiring for two pumps, I would use two relays. One of the last minute changes to the schematic was to use a larger FET (with integral fly back diode) for fuel pump relay. Driving two relays should be no problem. Of course if one of the relay coils fails shorted, both relays would be lost unless fuses were used for the activation coils. That would add another possible failure mode

I feel the same way as you about the relays. I wonder if the risk of the added failure mode is worse than the risk of a takeoff or landing mishap. But, I don’t like the thought of being trapped in the cockpit and fuel being pumped out in the engine compartment so I intend to use a relay. If someone doesn’t want to use it that’s fine too.

Wes

Re: The VeeCU

Posted: Sat Jun 08, 2024 8:08 pm

by WesRagle

Hi Guys,

When I get too much muck floating around in my head I have to stop and make some decisions just so I’ll quit worrying about it.

Today was the day to decide on whether or not to use a vented enclosure. The little vent hole and “hydrophobic” patch costs $10 a copy. The enclosure has a very tight silicon seal, so maybe no vent and some appropriate desiccant.

Seems to me a severe test would be to boil the enclosure, pull it off the fire, ice it (while still submerged), dry it, and open it up to check for moisture.

So…

Into the pot.

Bring it to a boil.

I set a timer for 10 min. and set down at the computer to study wire diameter/ampacity etc.

A couple of minutes later I heard a small explosion.

Obviously the seal is every bit as good as I thought

OK, that settles that. I need a vent. I thought it might leak, I didn’t think it would eject the connector.

Wes

Re: The VeeCU

Posted: Sun Jun 09, 2024 2:18 am

by WesRagle

Hi Guys,

So this is how the enclosure is shaping up in qty 1.

Enclosure w/Breather $22.24
Header w/Ferrites on all pins $32.25
Mating connector 30 Pos $11.47
Mating connector 18 Pos $10.69
Contacts Qty 41 $10.25
Cavity Plugs Qty 7 $00.70

$87.60

Not too bad.

The bad news is the crimp tool for the contacts.
Ref. https://www.mouser.com/ProductDetail/Cinch/599-11-11-615?qs=2w1RXwkPRjghTlaKVCFXWA%3D%3D&mgh=1&srsltid=AfmBOopj-FlEY0BloQoHC6hVah7ceNOCq6ZEABrrNU83M5IPsXW_DHUnKPM

$900.53

I contacted Cinch and they said they only supplied the crimp tool through distributors.

Good News/Bad News

The mating connectors have grommets that form a seal against the wires. There is a minimum diameter for the insulation for the seal to function as intended. Since this is an automotive connector the expectation is that I would be using wire with either TXL or GXL insulation. I intend to use tefzel wire which has thinner insulation. In order to meet the minimum insulation diameter I will have to use 16 Gage wire.

The good news is that with 16 gauge wire I don’t have to worry about current capacity on any of the conductors. I will also like the mechanical integrity of the 16 gauge wires running around the engine compartment. The bad news, well, I have to use 16 gauge wire.

A pic of the enclosure with a mating connector attached.

The mating connector instructions specifies at least 2" from the connector before applying a tie-wrap. So it looks like about 10 inches of clear space will be needed to install the unit. I intend to install it on the sloped section of the Onex firewall.

We’ll See,

Wes

Re: The VeeCU

Posted: Tue Jun 25, 2024 3:08 pm

by WesRagle

Hi Guys,

I made a video in which I attempt to explain my work on the VeeCU. It’s pretty rough, and the audio is horrible, but it’s my first video. I’ll do better in the future.

https://www.youtube.com/watch?v=n0_ms2Nh4tY

Wes

Re: The VeeCU

Posted: Mon Jul 01, 2024 9:09 am

by WesRagle

HI Guys,

A little progress. Just in from the shop. I’ve been working nights due to the heat. I just about have Frankenpanel built up to enable testing of the prototype.

I still have to wire it.

Does anyone know how long I can dry snap those injectors before they fail. What’s the failure mode? Do they burn up or just seize the pintle?

Forever Forward,

We

Re: The VeeCU

Posted: Mon Jul 01, 2024 9:21 pm

by Dave Wolfe

Looking Good Wes!

I got a chuckle out of the standard secondary ignition drawing more than your entire EFI! The standard secondary could use a ballast resistor or hei module to control dwell or something.

Re: The VeeCU

Posted: Tue Jul 02, 2024 11:39 am

by WesRagle

Hi Dave,

Over heating the secondary ignition coils has been a long standing problem. The guy right behind me at the airport is running a similar system on an O-235. He forgot to turn off his secondary and it fried the coils. The coils failed shorted and that took out his ignition module.

I’ve been told that Sonex has addressed that problem by using a secondary ignition module that shuts off the current after a couple of seconds of inactivity. I assume they act as before at idle, drawing about 3.5 amps per coil.

Talking to Dynatek tech support they suggest that if using the first generation Dyna-S ignition (which is what I have) for street driving use the 5 Ohm coils. They heat less and so are less likely to fail. If racing use the 3 Ohm. At the high RPM some of the drag guys turn the VW, the 5 Ohm coils run out of dwell time.

A lot of the Steve Bennett’s information is disappearing from the Great Plains web site. But before it went away I grabbed this concerning the secondary ignition coils.

"NOTES CONCERNING USE: The coils must be mounted in a position where you can direct cooling air on them. If mounted on the back of the accessory case, the coils must be insulated from the case. They must be grounded to the engine. The maximum operating temperature of the coils is 180°F. degrees. Keep them cool.

I’m still arguing with myself about how long I want to leave the secondary coils energized with no activity/rotation seen. It’s currently set to 10 seconds which would presumably allow for hand propping. But, do I really want to be party helping someone with a compromised electrical system get his/her “semi-electrical dependent” airplane started?

Don’t’ know. I have never hand propped an aero-VW.

Wes

Re: The VeeCU

Posted: Wed Jul 03, 2024 12:04 pm

by bvolcko38

My secondary coils, the red ones,draw 10 amps. 5 amps each I suppose as indicated by my ammeter. But this is only if the engine is spinning. If the engine is shut down the secondary draws zero current. On initial switch on of secondary,there will be a short 10 amp surge then nothing until you turn the engine over.

Re: The VeeCU

Posted: Thu Jul 04, 2024 12:12 pm

by WesRagle

Hi BIll,

That’s a lot of current. There is a lot to be said for bone simple, but …

Wes

Re: The VeeCU

Posted: Thu Jul 04, 2024 12:38 pm

by BRS

WesRagle wrote:Hi BIll,

That’s a lot of current. There is a lot to be said for bone simple, but …

Wes

My thoughts as well. I’m hoping that can be reduced. I’m thinking my toatal draw on a the Sportsman (SDS & avionics) is only around 17 amps.

Re: The VeeCU

Posted: Thu Jul 04, 2024 1:28 pm

by WesRagle

Preliminary testing indicates that with a constant 12 mSec dwell, and 3 Ohm coils, at 14 volts, maximum possible ignition current draw will be about 3 amps at 4000 RPM (AeroVee red line). I think a good rule of thumb for fuel injectors selection is 3 to 4 GPH static flow per injector. That produces about a 25% duty cycle at cruise (one amp total). So, in cruise, current consumption will be in the neighborhood of 3.5 amps plus fuel pump. Well under 2 amps + fuel pump at idle.

Wes

Re: The VeeCU

Posted: Fri Jul 05, 2024 11:00 am

by BRS

WesRagle wrote:Preliminary testing indicates … So, in cruise, current consumption will be in the neighborhood of 3.5 amps plus fuel pump. Well under 2 amps + fuel pump at idle.

Wes

Ah, well that paints a different story. Much more manageable. Thanks for the explanation.

Re: The VeeCU

Posted: Fri Jul 05, 2024 9:41 pm

by WesRagle

Hi Brock,

The secondary ignition module is a low side driver that normally grounds one side of the ignition coil primary with the other side connected to 12 V. The current flow through the 3 Ohm primary is only interrupted while the magnet is aligned with the hall sensor, which fires the plugs. So, most of the time current is flowing in the primary. Bone simple but very inefficient.

The VeeCU takes over the secondary ignition driver and uses it to drive/ground a 2.5 KOhm resistor in series with the IR LED of a high speed Optocoupler which delivers the pulse to the CPU.

So, instead of driving a 3 Ohm load the secondary module is now driving a 2.5 KOhm load. That will presumably eliminate most of the secondary ignition module failures. The CPU then drives the coils, but controls dwell time, which greatly reduces the coil current consumption. This will hopefully eliminate most of the ignition coil failures.

The other failure mode of the secondary ignition system is mechanical. Some units have thrown the magnet. That failure mode is mitigated by synchronizing an alternator pole with each of the secondary ignition pulses. Should either of the secondary ignition pulses go missing (for 0.2 seconds), while the engine is running, the alternator will take over to time ignition and injection. This will not be quite as accurate as a functioning secondary so the timing is retarded by three deg. while in this mode.

Wes