Reman ECM relearn ? (Page 1/2)
johnt671 JUN 20, 02:48 PM
Can anyone tell me what the relearn procedure is for the ecm on an 84? I just put a reman in and the idle won't go under 3,000 rpms after two drives. Thanks
Dennis LaGrua JUN 20, 03:20 PM
Was the idle fine before you put in the rebuilt ECM?

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johnt671 JUN 20, 04:51 PM
Yes.
theogre JUN 20, 05:59 PM
There is no learning for old ECM like all Fiero has except to reset the idle when you drive > 35mph.
"learning" to run to engine otherwise is mainly Close loop operation and ECM try to run w/o being lean/rich for the engine load for the last few seconds.

High idle can be ECM or whatever connected to it but most times is vac leak(s) anywhere in the car.
See my Cave, Vac Leaks

Possible new ECM is iffy, a connector or sensor is loose/bad but can be hard to find w/o ECM scanner and other tools.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

johnt671 JUN 21, 08:02 AM
Thanks again. I'm so frustrated at this point that I've forgotten the basics. I did have a few vacuum lines off when I did the tune up. I'll be going out in a few minutes to recheck it.

Does the PROM have anything to do with the idle?
johnt671 JUN 21, 10:33 AM
I checked for vacuum leaks but there weren't any so I took the new ECM out and put one of my spares in. Without even driving it the cold idle was where it should have been instead of 3,000 RPM's and the idle dropped to where it should be after a few munutes. This is why I'd like to know if the PROM has anything to do with the idle speed. If it does I could take that PROM out, put it in the new ECM, and be golden.
theogre JUN 21, 01:21 PM
WTF?
"New" ECM from dealer or part stores doesn't have a PROM and you must save the old prom for for this.
Plus PROM is made for trans on the engine. Wrong PROM for the car can cause odd problems.
johnt671 JUN 21, 03:33 PM
This is what I think is happening. This ties into the the thread I posted about the bucking problem and no SES light. removing the MSD stuff and new plugs, wires, cap and rotor took care of that problem, but not the SES. After trouble shooting the SES light IAW your advise, I took the ECM out that was in the car out ( it wasn't original to the car )and swapped the replacement ECM in thinking the ECM was bad. The car ran and the idle adjust after a short drive as it should have. Every time I stepped on the gas pedal and then stopped the idle was high, but would drop after idling. At this point I ordered a reman, and when it got here pulled the one out that was in the car, removed the PROM and put it in the new computer, which gave me the really high idle and it never adjusted itself.

This morning I put the ECM in that was in the car and got the results I posted above. So I went back to the ECM section of the Cave and found a link to the PROM #'s for the Fiero. The one that I took out of the old spare ECM was no were close to and # listed, so I assume the PROM was causing the crazy idle. I'm not sure if the PROM that's in it now is the right one because the shift light is working right but at least can drive it now. Still no SES light. I may have messed up the circuit board, so I have a replacement on the way.

Any idea where I could find the correct one.
Gall757 JUN 21, 03:50 PM
There were two manual transmissions (MY8 or M19) in 1984, each with 3 different PROM numbers. Do you know which transmission you have?
johnt671 JUN 21, 04:04 PM
I have the MY19 4:10 4 speed. I'd need either an DDB 0203, DDB 3044 or AMPL 9338.