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Morning DC... A good friend and I have been working on his 93 auto Vert. The main issue we have been dealing with is a bad idle. The car will start and run like a champ, until it reaches temp and BAMMM the idle will hit 1750 and not come back down. There has been so much time and money thrown at this car and we have not been able to get this bug out of the system. We are down to the ECM, when my buddy purchased his Vette it has what looks like an aftermarket ECM. Not having a way to test the ECM we were thinking a test swap. We have another friend that has a 93 6-speed. Our question, can we swap out the ECM's temporally to see if my buddies 93 auto will run right or will we screw something up if we start swapping out ECM's? Let me know what you think, Have a good day :thumbsup:
Scott
 

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I don't see why not ; calibration differences are mostly to do with trans operation.
Have you pulled the codes?

his Vette it has what looks like an aftermarket ECM.
Is it standalone unit or piggybacked to OEM ECM ?
If it is standalone then changing ECM won't affect anything
 

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Discussion Starter #3
I don't see why not ; calibration differences are mostly to do with trans operation.
Have you pulled the codes?


Is it standalone unit or piggybacked to OEM ECM ?
If it is standalone then changing ECM won't affect anything
Thanks for the reply :thumbsup: This is what I know, Saturday night we were getting (3) codes, (now keep in mind that this problem has been on-going for about three months) code 12, 34 & 44. 34 MAP sensor.... 44 running lean..... and I think 12 was running no problems. We put a new MAP sensor Saturday night and thought we had it fixed, but no, it started acting up as soon as it reached operating temp.
The current ECM is from a company here in Louisville and my friend acts like it is a factory ECM in a new box. I am not sure of that, but it is about the only thing that is left. I just wanted to make sure that we would not hurt the loaner ECM if we put it in my friends car as we try to get it running right.
 

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you can swap the ECMs, but you will need to take the PROM chip out of your current ECM and put it in the loaner ECM.
 

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you can swap the ECMs, but you will need to take the PROM chip out of your current ECM and put it in the loaner ECM.
OK so bringing the PROM chip from a car with issues to a loaner ECM wont bring any of the issues with it? Sorry for asking so many questions, this ECM deal is a bit out of my comfort zone.
 

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I have poor impulse control.
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OK so bringing the PROM chip from a car with issues to a loaner ECM wont bring any of the issues with it? Sorry for asking so many questions, this ECM deal is a bit out of my comfort zone.

The chances of the PROM chip being bad are slim to none. Typically the issue is going to be with the ECM itself. I'm on my 3rd ECM. My OEM ECM went bad on me (I had surging/ignition/power and no start issues), so got an aftermarket A1 Cardone unit (that went bad after 1 month), and then I got another OEM ECM from a corvette forum member. Haven't had a problem with the computer since, and I swapped my original chip into each of those. 92's and '93's will have the same ECM (part #16159278).
 
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