Hi Guys,
I found this interesting and thought I’d share.
A couple of years ago, when the VeeCU looked like this:
I got curious about what would happen if I pulled one of the plug wires. What happened was startling. The coil made a noise like a small machine gun. I called Dynatek tech support. It was then I learned that there is only one secondary winding on our secondary ignition coils. The plugs are wired in series. The spark jumps from the ground electrode to the center electrode on one plug and from the center electrode to the ground electrode on the other plug.
Evidence: Note the black insulation on only one plug of my bench test setup.
Anyway, I reinstalled the plug wire, checked that it still fired, and carried on with the project. When time finally came to “install” the VeeCU on the test engine I robbed the coils from the bread board shown above and installed them on the test engine.
Fast forward to yesterday. I did a mag check on the test engine and the secondary ignition failed with a drop of 300 RPM and missing and back firing. I switched the EIS to EGT and saw that the left front cylinder had gone cold. I switched the plug wires at the coil and saw that the cold cylinder was now the right front. That confirmed that it was the coil that had failed.
Here is a pic of the coils mounted when I pulled the plug wire.
Sure enough, the 3 Ohm coil marked 1w3 is the coil that failed. The machine gun sound could have been the secondary windings arching to the iron core. Regardless of exactly where the arch occurred, it must have damaged the coil, leading to its eventual failure. That very coil is now in the trash. I replaced it and the MAG check is normal again.
Moral: Never run a secondary ignition coil without both plugs connected and installed, or at the very least, with the body of both plugs electrically connected.
Wes
