Symptoms of a dead ECM

[dguy]

Check engine light is on solid, in run/engine off, start, and in run/engine on.  It remains  solid with the ALDL diagnostic pin grounded & the key on.

Engine idles at ~500rpm, smells rich.  Very easy to kill with even a gentle foot on the throttle; dies as though it's flooding.

The ECM fuse is good.

The failure follows more or less on the heels of an incident where a +^ve battery connection was sufficiently crudded up to have absolutely no power after shut-down.  I can't help but wonder if the battery connection failed in mid-flight, and a voltage spike killed the ECM.

Any thoughts?

[Kevin]

Sounds like it could be in limp mode. But what do I know? I have a four cylinder one if you need it. I don't like the side terminal batteries for the reasons above, they crud up too easily.   Kevin

[aaron88]

There is a chance that low voltage due to the resistance at the terminal can cause the computer to faut into limp mode (open loop no doubt).  It also means that your computer reset every night for the last little while.  The car was probably running odd for a few weeks.

Was the power disconnected for at least 20 min while you were charging the battery?

Aaron

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[dguy]

Thanks Kevin, but it's the car with the 2.8 which is the patient.

There is a chance that low voltage due to the resistance at the terminal can cause the computer to faut into limp mode (open loop no doubt).

That's what I'm hoping, though at this point the chief culprits should be taken care of.  I've had a once-a-year chronic problem with two terminal lugs, but hopefully that has been solved for good this time.

Was the power disconnected for at least 20 min while you were charging the battery?

I had the battery disconnected for a couple of days while I repaired the terminals.    I'm going to spend some time today checking/cleaning the remainder of the power and ECM-related connections...

[FieroBUZZ]

I probably have a couple of 2.8 ecm's here.  If I can find them..... auto or 4 speed?

[aaron88]

I have an 88 2.8 ECM but I don't think that one will work for you.

It also seems odd to me that even in limp mode (not sure if it's limp mode yet) your car doesn't run right.  Rich yes, but it shouldn't stall out.  There is at least one other problem, even if all esle is well.

Aaron

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[dguy]

It also seems odd to me that even in limp mode (not sure if it's limp mode yet) your car doesn't run right.  Rich yes, but it shouldn't stall out.  There is at least one other problem, even if all esle is well.

Neither am I...  but after checking out everything else I could think of, swapping ECMs was the only thing which cured it.