912 ignition issues

[avidflyer]

Hi all, a while back I picked up an 80 HP 912 that I knew had ignition issues. I figured I would try to sort out the problem before I mounted it on a plane, and so I built a test stand to mount it on. Did that over the last couple of days and this morning it was ready to crank over. I didn't have the chokes hooked up, so I splashed a bit of gas in the carbs and then put the aircleaners back on. It turned about 1/2 a turn and fired off. It did die almost immediately, but I manually engaged the choke on the carb that was closest to me and tried it again. It took off real quick then and ran relatively smooth for no carb sync other than eyeball on the throttle cables and such. It would die on the one mag every time. Swapped modules and such back and forth, and checked other things, and this is what I found out. I had hooked up a tiny tack for an rpm gauge, and so I took another one I had and started moving it from one spark plug wire to the next. I got no reading on #1 and #3 bottom cylinder spark plugs. I would guess that means no spark on them. #1 and #3 bottom plugs both fire off the same ignition module, but different coils. Can a coil be half bad? And then what are the odds of it happening to two of them? Ran out of daylight or I would have swapped plugs to see if I could make it move around, I'll buy some new ones if I can tomorrow. Can the spark plug wires be changed out in the coils, and if so what wire should one get? Thanks, JImChuk
https://www.youtube.com/watch?v=PWTE...ature=youtu.be