tylercamaro

iTrader: (1)

91 Trans Am, 305TPI 700r4. Started a few months back i was having drivability issues, car would idle high stumble places etc, turns out my TPS was bad (actually bad, i say this now for reason) as well as EGR was stuck wide open. I deleted the EGR, tuned that and Vats out and took a percentage of fuel enrichment out since she was pig rich for some reason (verified sensors before doing so),replace the TPS replace a few hoses that are in poor shape and hook the scanner up to it. OTC real time data scanner. Car runs fine for a week or so, then out of the blue 30 minutes into driving each time the car will stall and stumble all over the place. Hook the scanner back up and i have no TPS signal, test the sensor its fine, test for power to the connector and signal out of it and both are fine, No resistance with the computer and sensor unplugged in the harness so that verifies no breaks in the harness, plug it back in still no TPS signal. Like i said it idles and drives fine for about 25-30 minutes and then barely runs, CEL pops up and it runs like ****, CEL goes away and its temporarily fine. CEL stored code says TPS voltage low. Im lost here! HELP! This is what happens when i leave things alone!

RBob

iTrader: (1)

ECM is going bad.

RBob.

tylercamaro

iTrader: (1)

for reals? without a doubt? i know your a knowledgeable figure for you to say that, reading what ive done without any further diagnostic question baffles me.

RBob

iTrader: (1)

Drop the ECM down and leave it connected. Start engine. Rap on the ECM case such as knocking on a door. Does the engine change?

Can also leave it warm up and do the same. Heat makes the ECM fail easier.

Twisting the case a little can also show whether the ECM is getting intermittent or not.

If none of the above make a difference, engine-off, remove the top cover from the ECM. Start engine, gently press on various points on the board.

RBob.

tylercamaro

iTrader: (1)

Info i forgot to mention, could my moates g1 adapter be bad? what do you mean by twisting the case? the cover is off currently, its wrapped in saran wrap because the cover doesnt fit with the chip and adapter in

tylercamaro

iTrader: (1)

drive it around for 20 minutes let her sit in the driveway til she did it. still no data retrieved from the TPS at least not at idle, i cant multitask well enough while driving to monitor it.

rapping on the ECM itself causes no change. pressing on the board also no change.

RBob

iTrader: (1)

Grab the case by opposing corners and twist/flex it.

Shouldn't do that as the case is the heat sink for the ECM.

RBob.

Tootie Pang

iTrader: (2)

tylercamaro,

Whatever you find out, PLEASE post up and close the loop on this once you find your solution. SO MANY of these threads, the OP just disappears. I know you won't since you are a regular on this board. This is such a common problem on these cars. I am working on a very similar problem and will post up what I find out when I solve it.

I would suggest checking your grounds from the block and chassis.

My car has a stumble as well though it is a little more consistent. I am planning on running extra grounds with some #10 stranded house wire (THHN) from the block in two locations to the battery. Also from the ECU to the chassis.

I am also going to be taking a very close look at my EST circuits and making sure that the "signals" are perfect. One of my suspicions is the EST is getting whacked out.

I am also getting setup with ALDL Bluetooth to chart all of this junk.

I really want to get to the bottom of this.