Hi all,

I have a 1994 LT1. I took it out for a drive a couple weeks ago and everything was fine until I got about 20 miles into the drive. The motor began to stumble and was losing power. I pulled off the road and the motor died completely. I still had power to everything...just no motor. Engine temp was around 180 to 195. I waited a few minutes and got the motor restarted and headed home with no problem. It ran fine. Once in the driveway I connected my scanner and got a code 36... ign trouble/high pulse resolution fail A few days later I started the car up again in the driveway and let it run for about 30 minutes. I monitored the engine temp gauge and as it approached around 180 to 185, the engine died...like someone just turned off the ignition......no stumble or sputter. I did notice a slight stumble a few minutes before the engine quit. I checked with the scanner again but this time no codes at all. However I did a "check engine" light. The first and only time I ever got a code 36 was when I took it out for the drive when I first encountered this issue. From what I have read on previous posts concerning this problem I know that all of this most likely points to a bad opti-spark... but I had the opti-spark replaced with a new one last summer along with a new water pump. So assuming my new opti-spark and water pump are good, would the ECM or ECM harness be the next candidate?

 

Doesn't sound like an ECM issue, almost certain it is opti related.. Start by checking your opti wire harness for corrosion.

 

Thanks for the reply STL94. I will check the opti harness. I did forget to mention one thing that happened when I did one of my static startups in the driveway. I noticed the fan came on well before the engine got up to temperature. It stopped a couple of minutes later but the temp was still well below being hot. Would this indicate a possible opti harness problem as well?

 

Read the electrical part of this

http://www.mainstreamtopics.com/foru...rt-diagnostic/

Fan run ( usually key on ) generally indicates the ECM is in " limp home " mode because it is not getting all the inputs it expects to see and requires to run the engine

 

Thanks for the reply vetteoz. Your info adds another clue to the solving the problem. I had a new opti-spark installed last summer but I don't think the opti-harness was replaced with it. The water pump was also replaced when my mechanic (Corvette Care, Columbus Ohio) told that the old pump probably was throwing water and/or coolant into the original opti-spark eventually damaging it to the point of it needing to be replaced. I guess it's logical to assume that the old water pump could have damaged the harness input to the opti as well and may now be corroded.