Hey guys,

I took my 88 5.7 iroc on a bit of a road trip this past weekend, and i made the mistake of letting a relative of mine drive the car in an effort to save myself some money on parking at my destination.

anyways...

I got back to car and it had been left in the accessory position and the battery was completely dead, i jump started the car, and it immediately began to run like complete crap. the car usually runs with a check engine light for the mass air flow sensor, but that was no longer being displayed, and had caused me no issues before.

in an attempt to better understand the situation, i took the car for a drive, and after about 3 mins of driving around town, the check engine light came ON and the car began to behave normally again, which was great, because i had a ferry to catch. the car continued to drive perfectly fine and i pulled onto the ferry without issue.

on the other side however, the car began running like crap again, and i tried to drive the car in an effort to get it to behave properly again. but 20 mins on the highway later, the problem continued. being close to home, i decided to keep going and just limp home.

it was then that the service engine light came on again, and the car ran better, but was stumbling a little, and made it home and just left it over night.

NOW, when i finally got around to looking at the car this morning, i could not get the codes to display on the check engine light, not even code 12. i checked the continuity between the aldl connectors and the ecm, all good, i checked all of the fuses, and even swapped out a replacement ecm (except chip) to no avail, additionally, the car will idle high and run the same regardless of whether or not the MAF sensor is connected or disconnected.

has anyone had any issue similar to this before?

I'm kinda stumped, and cant help feeling it wouldnt have happened if i hadnt let someone else touch the car lol.

thanks in advance!

 

If you know that the spare ECM is good, it points to a bad MEMCAL. The PROMs do lose data, given the years. When the car acts up, and even when it doesn't:

Look for the SES/CEL light blink. The blink proves whether the ECM is running from the PROM or not. This is:

At key-on, engine-off, the SES/CEL should turn on briefly, blink off (!), then turn on solid.

Can repeat the test after ten seconds of key-off.

No blink off, ECM is out to lunch. But can be caused by a bad PROM.

RBob.

 

Rbob,

The ses light flashes on when the key in on position for a fraction of a second, and then remains off....

Is that equally definitive?

Thanks again

-Greg

 

Yes, either the ECM or the PROM (on the MEMCAL) is bad. No SES means it is out to lunch in limp mode.

RBob.