Ignition woes: runs on top or bottom but not both

914986 · 05-14-2017, 06:38 PM

This car had ignition problems just prior to my purchase, which the prior owner's mechanic attributed to a bad coil. Coil was replaced and no problems for about 800 miles.

Then I got an occasional flash of the CEL for a couple days, followed by severe bucking but made it home. Then it would try and start but either run rough and die, or not start at all.

If I unplug the rear ignition module lead (which I believe to be the lower) it will start, idle and run. I can also plug the front lead into the rear module, and it will run. I believe based this test and a visual on the distributor tells me both are working.

It will not run using only the rear lead into either module or with both leads plugged in.

My guess is maybe a bad wire in the rear ignition module lead, but I'd like to tap the collective experience and wisdom before I start throwing too much time or money at the problem.

Any and all help is greatly appreciated!

I'm getting re-acquainted with the 964 after 17 years away.

914986 · 05-23-2017, 04:54 AM

Problem was a plug wire was left disconnected when the engine was pulled for a re-seal and clutch job.

johnrod · 07-29-2018, 08:32 PM

I know this is an old post but I am having the same problem. When you said a plug wire was disconnected did you mean sparkplug? I looked at the sparkplug wires and they are all correct. I can run the upper or lower distributor with the longer module plug, but it run at all with the shorter plug.

914986 · 08-20-2018, 05:07 PM

Quote:

Originally Posted by johnrod

I know this is an old post but I am having the same problem. When you said a plug wire was disconnected did you mean sparkplug? I looked at the sparkplug wires and they are all correct. I can run the upper or lower distributor with the longer module plug, but it run at all with the shorter plug.

I had a sparkplug wire that was totally disconnected, and laying up on top of the engine. I think it would find ground when it got tousled around to the right position, and that's what caused the "Christmas Tree Effect".

Have you made sure both rotors are turning, and in sync?