Hey all; I have a 1988 Camaro SC with a 1986 IROC Z engine,
vin F LB9 TPI 305. It's been running rich lately and I've been going through certain diagnostics and fixes and none seem to be working. So I figured I'd move onto the ECM and PROM next.

If you were to analyze my receipts for work done to the car by the previous owner, you will see that the ECM and engine were bought at the same engine place, but on different days. This makes me suspect that PERHAPS the previous owner who dropped the LB9 into my car may have been sold the wrong ECM and/or PROM. It could be possible he was given an ECM and PROM for a 350, which would explain why so much fuel is getting dumped into my engine, because a 305 is set up for 19 lbs/hour, and a 350 injects at 22lbs/hour.

So I need help in identifying my ECM and PROM to determine what they were set up for. Is there any codes I could use to see if they're from a 350 perhaps, or for the wrong engine?

Any help is appreciated on this one folks.

Kev

 

The ECM should have a white sticker on it. There will be a GM
service number on it like122????, and on the right upper corner
of the sticker will be a four letter code, this is the prom code.
Pull the trap door off the ECM and look at the prom, it has a silver
sticker on it that should have the same four letter code that is on
the ECM sticker.

If you give me the ECM service number and the prom code from
the ECM sticker and also the code from the prom if it is different,
I can tell you what ECM you have and what the prom is for.

 

Swapmaster is right on as for ID.

As for having a 350 chip in your 305, it would actually make you run way way lean, not rich. The MAF is the same 305/350 and all the input is the same (and the ECM doesn't care what size the engine is either in MAF). So if the ECM thinks you have bigger injectors, it simply opens the injectors less for a given reading on how much air is moving.

In other words, you are most likely on a wild goose chase as for wrong ECM/PROM. It certainly wouldn't have just become an issue. If you can spell out what you've checked so far we can probably help you more though.

 

Ed, you da man.

 

Having a different computer in your car wont do anything, I have a back up computer that is in my car that was originally out of a Grand Am, so if that tells you anything. My TA is an 86. The prom though could be something to look at...

BTW does it have a AFPR on it check that...

 

GM ECM's fit many cars. One service number may fit Camaros.
Cavaliers, S-10 trucks or more, it's the PROM that tells the ECM
what car it is in and how to act.