Hey everybody, I recently bought a 1985 Pontiac Grand Prix, with the V8... The previous owner stated that it needed a new prom chip, I've had it checked at the local GM dealership to confirm the issue & it is indeed the prom chip, problem is, I can't seem to find one for it, I tried Hypertech but they don't make a chip specifically for that year model car, also have went to Autozone & they can get a stock replacement chip, which is what I need & want, but their vendor, CardOne, is saying that there are four letters & numbers on the chip & that number is needed to order the correct replacement, problem is, when I look on the stock chip, there is no such sequence, there is only a Malaysia 980 with the Delco stamp under it with some numbers which I can barely see due to the plastic tabs holding it in place, then at the bottom of the chip, there is a sequence 8518AF 34023, it also has the letters CPN stamped on it that Hypertech needed as a reference, but when told those letters they had nothing in their system that could be used..... If someone out there has had the same issue or has any information on where to go to get this chip it would be greatly appreciated.
Prom chip
- Thread starter CrownPrince78
- Start date
- Status
Appreciate the feedback DoubleV, I've looked into replacing the ECM & have been getting different answers for that too, the part number that they seem to have doesn't match up with what I have so I've been told that there "could be" different ECMs for that car, or that it doesn't have the chip I need... I've had G & B-body cars before & have never had this much trouble getting what I needed for them.
This is an example of prom identifier, along with ECM codes, etc. It's for an '87, but will give you an idea of what to look for.
http://www.3rdgenformula.com/87/promcodes.htm
If you are still running the 4bl CCC carb and dizzy, then I would think the ECM from just about any V8 G-body will work for you. I have an '85 Elky, and swapped in an '87 Monte Carlo SS ECM with no issues. THe ECM is really pretty dumb. It looks at O2 inputs, TPS inputs and a couple of others, and then adjust your carb mixture and timing. It has no idea what gears you are running, what tire size, etc.
Here's some more info I did by digging through the net. See if these numbers match anything you've got there:
ECM: 1226865
GM PN with PROM 16044239
PROM ID 4240CPN
Here's a link I found, although they are out of stock.
http://www.stockwiseauto.com/product_in ... _id/526616
Might also try these guys:
http://www.carcomputerguys.com/store/
http://www.3rdgenformula.com/87/promcodes.htm
If you are still running the 4bl CCC carb and dizzy, then I would think the ECM from just about any V8 G-body will work for you. I have an '85 Elky, and swapped in an '87 Monte Carlo SS ECM with no issues. THe ECM is really pretty dumb. It looks at O2 inputs, TPS inputs and a couple of others, and then adjust your carb mixture and timing. It has no idea what gears you are running, what tire size, etc.
Here's some more info I did by digging through the net. See if these numbers match anything you've got there:
ECM: 1226865
GM PN with PROM 16044239
PROM ID 4240CPN
Here's a link I found, although they are out of stock.
http://www.stockwiseauto.com/product_in ... _id/526616
Might also try these guys:
http://www.carcomputerguys.com/store/
Hey darbysan, thanks for the info... Everything on the car is still stock, 305V8, 4bl Quadrajet carb, etc... I was looking at the diagram of the chip for the '87 & my chip does have the letters CPN stamped on it but unfortunately there are no numbers, although there is the 8518AF on it under the Delco stamp but there are some more numbers shortly printed on the chip after that, which are 34023. As for the ECM part number 1226865, I've been given that number from all the auto part stores & have been told that that part number should be on the ECM, but when I showed them the numbers I had on there, Number 7-7169, DC Code 0713MT, & then there is the bar code with 131977716906632 REMFG on it, & that's when they say that it could be another ECM used for this car... If I can use another ECM for it off another Gbody without any issues I will, but I just want to make sure I get the right parts.
Can't help much more. Your code 7-7169 leads me to think this might be a 1227169 ecm, which was for an '86 305 4bl pontiac. That, or a 1226870 should be equivalent of what you are looking for, as long as the pins in the connectors line up the same.
Why do you think your Prom is bad. What are the indications?
Why do you think your Prom is bad. What are the indications?
The previous owner had stated that according to his mechanic the reason the check engine light was on is because it needed a new Prom, I took it to a local GM dealership & had them put it on the diagnostic machine so I could confirm the issue, they came back & told me that it was indeed the Prom chip but they couldn't get the part I needed because it was discontinued through GM... The car is using a lot of gas, running a little rich, has a hesitation at a stop light/sign, & after turning off the car the motor continues to sputter for a few seconds... Given the numbers you've provided, it leads me to believe that they may have replaced the ECM at some point with one out of another vehicle, I've found a replacement ECM that fits an '85 GP through Cardone, states on the description that it is programmed at the factory with everything it needs, but I'm not sure if the chip comes with it, or if it has been bypassed & I just plug it in & go. There are ECMs for other model cars that need the old Prom chip to be transferred into the new ECM & it specifically states it for those models but doesn't say for the ECM that I need... I do appreciate all the info you've provided, it is helping, just trying to make the best move.
You are right darbysan, the ECM that's currently in the car, 1227169, is from an 1986 GP 4bl V8, that is one reason for all the confusion regarding the ECM, I ran the numbers on Autozone's website, they have it listed as part number 77-7169 & if I replace the ECM I need 77-6865 which according to them is the correct ECM for the '85 GP V8 5.0... Still doesn't say if it needs the chip, only states that OEM #1226865 units are pre-programmed at the factory and ready for installation with no further programming required.
I think you're making to big a deal of this. You have the chevy 305 with the Rochester 4bbl and a 1 wire oxygen sensor. That 1 wire o2 sensor isn't really doing much as far as adjusting air/fuel mix or timing. Just get the ecm from an 85 Monte carlo v8 and or SS and you'll be fine. Plug and play. I imagine any Monte SS 85-88 ECM would work fine. 50$ on ebay, it will take 10 minutes to install yourself. My car has a 92 Chevy full size pickup 5.7 ecm in it. These things are pretty interchangeable.
Appreciate the input oldmansmonte, think I have the issue taken care of, if not, I'll see about switching the whole ECM out as suggested.
- Status
