Just bought a 91 RS 3.1 auto and it's missing both ecms. I'm just curious if you have to get a ecm from the same model car(V6 auto). I have done some searching and seem to be finding mixed answers. I'm sure the future holds a ls swap but I just wanted to get it running and driving for now as I have to many current projects. Any and all information is greatly appreciated and thanks in advance.

 

When you say "both ECMs" , It begs the question, what, exactly are you missing? You car only had one ECM from the factory, a big silver box that is mounted where most cars have a glove compartment...

 

You are correct but it also has a chassis ecm or some call it the safety ecm which I believe controls air bags but I'm not positive on what all it controls. It is located to the right of the steering wheel under the dash.

 

There were a handful of ECMs that were used among other cars...like my research showed the ECM from a 4 cylinder S 10 is the same as a TPI car...how accurate that is though im not sure as I didn;t look hard into it lol
but the PROM is what tells the ECM what its operating....the 2.8 and 3.1s used different ECMS though I believe...


The air bag one im not too familair but a quick ebay search turned up this

"90-92 CAMARO SAFETY COMPUTER 16081221 AIR BAGS SEAT BELTS MODULE CONTROL ECM"


the engine ECM you can probably buy used from e bay as well or you can grab one from rockauto but those rock auto ones cost more...
you'll need to get a PROM though specifically for your 3.1 / auto trans from ebay or a salvage car....those aren;t available as far as I know.... unless you get a ECm with the PROM still installed...

"Prom Chip AUJW 1990 Chevy Camaro Pontiac Firebird 3.1L 1227730 Memcal 16150975"

i THINK it was the same from 90 - 92 as other listings list it as 90 - 92 ...youd have to do a little more research though.
You can get everything from ebay now for probably less than $200 Id say

 

I love rock auto...hate their shipping prices....


i clicked the part number and it shows what cars the ecm fits...what specific model / engine though im not sure...

BUICK CENTURY 1987-1988
CHEVROLET BERETTA 1987-1993
CHEVROLET CAMARO 1990-1992
CHEVROLET CAVALIER 1987-1993
CHEVROLET CELEBRITY 1987-1990
CHEVROLET CORSICA 1987-1993
OLDSMOBILE CUTLASS CIERA 1987-1989
OLDSMOBILE CUTLASS CRUISER 1987-1989
OLDSMOBILE FIRENZA 1987
PONTIAC 6000 1987-1991
PONTIAC FIREBIRD 1990-1992
PONTIAC SUNBIRD 1990-1993

 

https://www.ebay.com/itm/114995962006

Wouldn’t worry about the derm unless you want drivers side airbag.

 

Thanks for the replies, I appreciate it and I actually learned something.