This Gremlin has been pocking inside my motor for two years. Now it's time to get him. I have a calif. 1981 Vette with a ZZ3 motor high performence coil, new wires,new plugs. The car runs about 170 degress and has been dyno (on the tread mill) tuned. When running about 3000-4000 rpm the car runs cool and fine. After about an hour or so, if I go into stop and go traffic, sometimes it starts to miss fire. As if someone is pulling plug wires off and on. Then if I hit the freeway at rpm 3000-4000 it might go away or stay. If I turn the car off and let it cool for several hours, the miss firing is gone. Then I can drive the car in stop and go traffic freeway speeds the works for moinths and it runs fine. Then out of the blue, it appears again. I have replaced the coil, wires, plugs, distributor cap, the computer chip under the dis. cap (but not the computer chip under the distributor). The car has all emmision controls connected and has the main computer brain (stock) mounted under the dash. I was told that my distrubitor needs to be replaced. But if that were the case, would it not act up all the time? My feeling is that the computer chip mounted under the distrubitor( the one where you have to remove the distrubitor to get to and replace) is heating up and shorting out. This event never happens when the car runs cold, only after freeway speeds then right into stop and go traffic. It has never occurred while operating at high rpms. Then there are those times when it runs hot and never happens. Please help..S.O.S. thanks :U

 

When you replaced the ignition module (the computor chip under the distributor cap) did you use a liberal amount of dielectic grease. The grease is used as a heat sink to pull heat away from the module. If the module overheats it will develope a miss as you described, then go away when thing cool down.

 

Yes, in fact I replaced that module thinking that was the problem., but it didn't work., the problem continued. I purchased that part from GM and used all the grease that was supplied with that part. Perhaps I should have used more grease?

 

I am having a similar problem with my HEI in my '69 except that the coil blows up. Been waiting to get released from called up Active Duty with the Navy before asking for help so that I can be with "the other woman" when suggestions come in. I will be follwing this thread to see some suggestions.

Good luck, it is agravating!

From Bahrain

River Rat (Desert Rat for now) :flag