Over the past year or so, my 86 iron duke has eaten no fewer than six ignition control modules- all from various sources, high buck ones (including an NOS GM), low buck ones and several in-between. The outcome is always the same, install new ICM and it starts/runs great for a few weeks/months, then random hard starts/missing for a while, followed eventually by dead on the side of the road. No codes, no other problems. Plugs and wires replaced, gapped, inspected, etc several times without effect. I even replaced the distributor with a new one. Each time, I used the the heat sink paste, cleaned and inspected leads, connectors, grounds, etc. Yet the pile of dead ICM's grows.
So... has anyone found anything better from GM or aftermarket ? I've searched pertronix, MSD etc without success.
Blowing ICM like that Is Not an ICM problem but 1 or more other things are causing ICM death. Can be issues on low volt side, high volts side or combi of both.
Just 2 Example: F'd plugs or wire to them can "short" high volt anywhere often frying the Coil shorting internally then fry ICM. Many install ICM wrong w/o silicon or heat sink grease &/or use crap screws cause crap Grounding for ICM both can kill it.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
After that many ICM replacements, it would seem the problem is elsewhere. The ICM is being affected by that problem. Example, when I purchased my 86 2.8 I had a break-down several weeks later. It was as if someone turned off the ignition switch. I steered off the road to a safe area and popped the decklid. Battery cables were clean & tight, I wiggled the wire harness around the dizzy area. All seemed ok and the engine started up with no issues. This happened a few more times over a long period of time (several months) as I recall.
Long story short, I began tugging on wires while the engine was idling including right up to the ECM behind the center console. Bingo!!, it was a wire at the connector to the ECM. I could move it using an ink pen and the engine would hesitate. I believe it was a white wire that led to the ICM connector. I used an ohm meter to check that wire for continuity end to end. Recrimped as required and never had an issue since. Perhaps high resistance in that wire could kill an ICM .
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
Originally posted by Spoon: Long story short, I began tugging on wires while the engine was idling including right up to the ECM behind the center console. Bingo!!, it was a wire at the connector to the ECM. I could move it using an ink pen and the engine would hesitate. I believe it was a white wire that led to the ICM connector. I used an ohm meter to check that wire for continuity end to end. Recrimped as required and never had an issue since. Perhaps high resistance in that wire could kill an ICM .
Iffy Wire(s) to/from ECM won't kill the ICM but sure won't help.
Think White is ECM Timing to ICM after ECM controls timing after starting the engine & only 5v pulses.
While all of the above can be true, don't underestimate the absolute crap quality some brands' ICMs are. I used to go through ICMs like crazy too until I stopped being a cheap-ass and got myself an ICM from a reputable brand - which was quite a bit more expensive than the ones I used to buy. Haven't had a problem since (and I'm guessing it was 15 years ago I replaced that ICM).
PS: Can't remember for the life of me which brand it was unfortunately...
Oh - didn't read properly. You already tried the expensive ones. Still, it could very well be that if you get an original from a junked Fiero or so, it will last a lwhole lot longer.
1st thought was an NOS GM but that died too and that's not easy. Just a guess but have you tried replcing the coil? It could be there is some high voltage leakage into the coil primary to a degree that it functions but will eventually fry one of the semiconductors in the ICM.
Any of the secondary ignition components can put a strain on the ICM. Bad wires, plugs, or even the ignition coil can cause a failure. A weak pickup coil in the distributor can be at fault, too.
Why haven't you replaced the ignition coil. Does your tach flutter when you are at a deep throttle position at low RPM? If so your ignition coil may have compromised insulation allowing secondary high voltage shocking the ICM to death.
Problem is even the "high quality" ones are made in the same chinese factory as the "low quality" ones. Only difference is just the brand name. Not saying that is your problem but I wouldn't be surprised if the one you claim is "high quality" is made alongside the "cheapo" one.
I had a similar problem back in the day. Go for a spirited run at night, park somewhere real dark, and check to see if the bottom plate the ICM mounts to on the distributor is glowing hot. Mine was. Turns out the inner shaft on the distributor was binding, heating everything up, and cooking the ICMs.
I suppose you could just feel the bottom of the distributor, but be careful, mind was blistering hot.
