Help!
My 86 IROC is completely losing ignition when in gear & the body shakes. Started as hiccups @ freeway speeds (stutter, stutter then run as normal). Now she stutters, flashes the SES lite a couple times & dies, SES lite stays on and radio loses power but headlinghts do not. So I'm now coasting @ 65 70mph for 5-7 seconds before she decides to run again then it picks up just fine until it decides to do it again which is usually the next slight bump in the road. It's now also happening at city speeds if the road is rough. The ECM has never set a trouble code for this event. The dealer looked for this problem in late may and couldn't positively identify it (much less frequent at that time) but changed the IAC valve as a precaution. That seemed to lessen the problem (only occurred 4xs over the next 2 months) until Friday when it came back w/a vengeance. Dealer now says they can't talk to my ecm even after reinstalling the factory PROM. They want to replace ECM AND PROM (350-400$?) just to continue diagnostics. PLEASE tell me someone else has had this trouble!! I may be naive but I really believe this is electrical somewhere & not in the ECM. Any ideas of other things 2 look for would be so GREATLY APPRECIATED!!!! (sorry 4 the run-on sentences)

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86IROC 305TPI
1-3/4" SLP Headers-HiFlo Cat-Flowmaster
B&M Shift Kit & Megashifter
3.73 rear
Mystery-Go-Fast-Chip (label says ZL Ind.??)
(All xcept SLPs instld by prev owner)

 

i feel ur pain my friend but my problem is worse. It happened a couple of days ago. I had the radio on and my lights as well. Anywayz i was driving then all of the sudden my car drops rpms and the radio goes off then it comes back on and everyhting goes back to normal. then it happend again this time killing my car. to this day I dont know what it is and now its to the point of as soon as my car is turned on it dies. what the hell?

 

Probably not what you wanted to hear, but my Corvette had similar symptoms. Every time I would hit a bump in the road the SES would light up and engine would bog down, then suddenly come back to life. Turned out there was a hair line crack in the ECM, and every time I hit a bump it lost connection. Got a new ECM for about $100, installs easy, fixed the problem.

 

Thanks everyone. Just came back from dealer after replacing positive battery cable that was severely damaged being pinched between frame rail & headers and trouble seems to be resolved. Of course, that's what I first thought last time too so time will tell, but she was smooth as silk all the way home.