garrett376

I am curious how everyone's engine behaves when running on only one side of the ignition at idle. If you unplug one of the combination plugs at the coils (not the high tension wire), can you start your car and does it idle normally?

On one of my cars, if I unplug one of them for the lower bank, it won't start up. If both coils are plugged in, it runs fine otherwise.

One the other car, I can unplug one, it runs fine; if I unplug the other and plug the prior one in, and it idles but backfires.

Again, both cars run perfectly fine, no pinging, nothing! Sounds like it's time for some new coils? Thoughts?

KirkF

I tried this test last year on my car when I was trying to diagnose a running problem.

I disconnected the primary and secondary distributor coil leads one at a time. The car seemed happier runniing on the primary coil rather than the secondary.

I have heard it should idle equally well on both. ?

Kirk

Heirsh

Mine starts and idles fine on either. I originally had a bad coil so I did a few experiements to find the bad one.

tbennett017

Are you trying to diagnose a distributor belt problem? Mine runs/starts fine on either...

garrett376

I was actually diagnosing an oil leak on the right side, and if the lower plug was removed from the #5 cylinder, I could watch it leak (darnit!). Well, initially I tried to disconnect the entire lower half by unplugging the module at the coil for the primary distributor which runs the lower plugs, and it would not start. So I reconnected it and it started fine. That's how this whole thing began! I was not even looking at whether the ignition was healthy or not!! Then I tried my other car since I was curious, and found that car to be gurgling on one coil versus the other... hmmmm

I just ordered two new coils, in addition to the damn $1.50 gasket that I re-used this last time I had the cam towers apart!!!! Shame on me!!! I'll never learn! Now I gotta wait till Tuesday to get my gasket, and take it for a ride!!!

ddubois

I'll bet the new coils will fix it. After replacing the ignition wires, caps, rotors, the shredded distributor belt, and one coil that was bad, mine ran like crap on just the old 'good' coil alone. After I replaced the second coil, it purrs on either.

garrett376

Hope so!! The car's got to get ready to run Miller Motorsports Park in your home town at the end of September!!! Come check out the action!!! Sept 28-30.

ddubois

I plan to be there on Friday 9/28 for the DE and probably volunteer on race day. Don't often get the chance to run the full track! I was there yesterday for a DE on the west track with perfect weather - 4 sessions sunny/dry and 1 session of thundershowers.

Oracle

So, here's a question..
How do I know if both coils work? Is the difference from 1 to 2 coils really noticable?
Which wire should I pull out to test both?
Engine running or no?

Thanks
Jasper

springer3

Double-check the firing order on the distributors. On my car, two wires were reversed on one cap, but perfect on the other. It ran fine on both, and on the bank with the correct firing order. On the system with two spark plug wires reversed, it ran really crappy.

pete000

Do not drive the car on one coil. It will ping like crazy ! Yes it will run unless your belt is broken. Then it will only run on the first one.

dougn

it should start and idle smoothly on either ignition

springer3

Agree. Standard pre-take-off check on a dual-ignition aircraft engine is to switch to single ignition positions to check the magnetos. You lose a few RPM, but you should taxi back to the ramp if the engine runs poorly or dies on one ignition system.

garrett376

Ok, with new coils, car #1 runs fine idling on either ignition system! I'll have to order a new set of coils for the other car! At least they're just $50 each... but it sure adds up with two

garrett376

By the way, as a completely electronic part, how/why does a coil wear out?