Demo man

Well I (usually) like to meet new people, so I might just do that.

I see on the related thread below, that the OP had to have his ECM rebuilt to correct his similar problem. I suspect that I may have to do the same.

antfarmer2

Try the Fonzie trick smack the ECM while running and see if it changes.

Demo man

Haha..! Yeah I disconnect the battery everytime I park it in the garage, otherwise it will pull the battery down over a couple of weeks. That obviously doesn’t help, but I haven't tried hitting it with a hammer yet... although the temptation is getting stronger all the time.

antfarmer2

Not a hammer just a good smack and not kidding.

Demo man

Yeah, I knew you were serious. Was just attempting to add a little levity. Actually, I would probably tap it with a hammer anyway, to be truthful. A sharper lick would be more likely to produce the result we are looking for.

C4vettrn

What size injectors was it replaced with ? Should retune regardless.

Did you verify the IAC valve is adjusted and functioning correctly ?
If you haven't already I would start by following the FSM steps to setting up the TB blades/idle and sensors also check the play and bushings on the blades shaft.

Demo man

I did, yeah... and went through all that on the '86 as well. Didn't change a thing...

I don't remember the difference in injector size. I know it wasn't a major increase. It didn't make a noticeable difference in the way that it ran.

Demo man

Just to let you all know; the problem is definitely in the computer.

I tried hammering on it with my fist as someone suggested, and that fixed the problem temporarily each time.

Haven't had time to drive the car in the last year, but I need to either figure out how to repair the lose connection in this one, or swap it out.

Preferably I'll be able to fix this one... Otherwise I'll need to take the new one to a tuner, and have it reprogrammed to compensate for the long duration cam, etc...

Kevova

The 92-93 LT1 ECM are not always easy to find most have to be rebuilt or exchanged. "You have to have one to get one". The programming (PROM) is a replaceable chip under door on ECM. There was a ECM on parts page. It's very possible problem is a circuit board or soldier joint within ECM, since banging on ECM has effect on how car runs. Carefully wiggling or moving wires at different connectors trying to cause and correct condition, would indicate a connector issue. Lingerfelter maybe able to steer you to tuner or supply PROM.

If you have to rebuild your ECM ,remove PROM prior sending it out. You may need to keep door and screws, contact rebuilder to be sure.

JimLentz

I used SIA Electronics to rebuild my '92 ECM.

Natrlone93

Me too on my 93. Great job.