the ECM in my '86 IROC died today, I have a complete TPI setup from an '89, can i swap ECMs and use the PROM from the '86 in the '89 ECM without trouble?
I know the '89 has VATS but isn't that coded into the PROM not the ECM itself?

thanks,
Colin


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Webmaster: www.IROC-Z.org

 

The VAT's is in the EPROM. I think someone replied to you before that both the '86 and '89 use the 165 ECM, so you should be good to go using the '86 EPROM in the '89 ECM.

 

actually I posted it on the PROM board because I wasn't sure which board would be best to ask one

i'm happy about that because I definitely need to get this car running, it died on me on the way home from getting some supper last night, had to walk over 3 miles home

i'm sure it's the ECM, the check engine light was flashing in time with the missing of the engine and then it just shut off.. i can crank it and it will fire but it will not idle, runs very rough and the check engine light will flash off each time the car stumbles and flash on each time it catches..

the lights both in the gauges and the headlights don't dim while the car is missing so i know it's not a ground..

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Webmaster: www.IROC-Z.org

 

well, i just got back from changing the ECM to the '89 one..

there's no difference in how it runs compared to before this last ECM died..

i'm starting to wonder if maybe the ECM isn't being shorted somehow..

the only thing i can think of that might cause this would be that i didn't reconnect the ground to the rear passenger side of the head.

My Dad told me that i shouldn't have to bother with it becahse the engine is already grounded through the motor mounts.

I 'did' have the ground hooked up to one of the bolts on the TPI system until yesterday, though..

ideas? I know this new ECM is good, it's a brand new remanufactured that was put in my friend's car about 6 months before it was totalled..

could the PROM be bad? I can't see why since the car runs with the new PROM and wouldn't with the old ECM..

how can I test my ECM as the car is now so I don't run into this again?

thanks for the help guys, I really appreciate it
Colin

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Webmaster: www.IROC-Z.org

 

Motor mounts are rubber.

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yes but there are metal bolts going through the brackets

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Webmaster: www.IROC-Z.org

 

Connect the ground strap.

The grounding property's of the Motor Mounts is Questionable In My Book.




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver 14.82 @ 91.1 (faster than Ed)
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well..

i had the ground strap temporarily grounded on my plenum, i don't think this is the problem..

there's been no change in how it runs no matter whether the strap is on or off..

man, i dunno, i'm about ready to sell this time sometimes.. anyone want an '86 IROC with 4.11s?

seriously, though.. i don't understand why the car runs like a top with the EST disconnected but connect the EST and the engine runs so bad

ideas?

 

btw: car runs the same as before the other ECM went, EST on == bad idle, no power, misfiring, EST off == good idle, lots of power (even a bit of wheelspin , no misfiring)..



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Webmaster: www.IROC-Z.org

 

could it be the PROM?

i used another ECM i had (same model) but used the '86 PROM from the old ECM and put it in the new one..

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Webmaster: www.IROC-Z.org

 

CO, What was the codes stored in the ECM? Have you looked into the MAF? Fuel pump? Try one thing at a time, however, the first thing to do is hook up that ground strap and reset whichever ECM you want to use. Also, had you performed any maintenance on this car previous to the problem arising? Wires in correct order? sticking injector? Also have you checked the wiring going to the knock sensor? If all else fails it may be the PROM itself.

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"Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason, than that of blind-folded fear."

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Since you mention grounds, did you jook the small strap up from the engine to the firewall?