n1ffer

I was hoping some of you fine folks could maybe help me out. I have a 1983 Trans Am with 5.0 Crossfire. I bought the car about a year ago and have been doing work on it slowly.

I was going through some paper work that came with the car and found an ECM installation instruction guide. Written on the guide in handwritten ink was some part numbers. One part number - 1226865 - is an ECM for a 1985 Trans Am 5.0 with a carburetor according to many web sites. None of the other part numbers written are able to be associated to an ECM.
I checked the ECM in the car (which was not mounted and extremely clean compared to the harness connectors, and the connector tabs were broken) and the only number I could find on the ECM was 8671754 on a sticker on the housing, and a bar code - 85202810207193. I wasn't able to cross either.
I am guessing that based on the paper work, the unmounted ECM unit, how clean it is, the broken connector tabs and the bar code starting with "85" that I probably have the wrong ECM - one for an 85 carb TA.
Either way, for $80.00 I can get a reman and gain piece of mind.
What I am running into is that four websites, Autozone.com, Advanceautoparts.com, Rockauto.com and ACdelco.com all show two ECMs for a Crossfire 83 TA. Either a 1226025 or a 1226026. They state it would be labeled on the ECM. There is no label on my ECM. Any guesses or direction or resources on how I can find out if I need a 1226025 or 1226026?
Any thoughts about if a 1985 carb ECM could run a 1983 Crossfire?
Most importantly, if anyone could help me with the correct part number for the correct ECM I would be very grateful.
Thanks!

82CrossFire Z28

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n1ffer

I see you have not gotten any responses yet. I have an 82 Camaro with the LU5 CrossFire engine. The ECM in my car is a 1225550 unit. I do not know if GM changed the ECM for the 83 cars. The ECM units contain a PROM chip which is a programmable read only memory chip. This contians the data specific to a cars engine and how it is controlled. A PROM for a carb car will not work with a CrossFire engine. The CrossFire engine has two TBI fuel injectors. The injectors are controlled by the ECM. A Carb car does not have the fuel injectors so its PROM chip will not have the information required to operate the injectors. It is possible that the 85 ECM in you car has had the PROM chip replaced or reprogrammed to work?? with the CrossFire fuel injectors. The only way to know for sure is to ask the individual you bought the car from how he modified the ECM to work with the CrossFire engine.

As for the correct ECM number for your car, have you searched this board to see if you could find anything??? Try CrossFire or LU5 for the keyword. You might also want to ask in the History board.

I would also suggest that you visit www.gmparsdirect.com and send them an email with your car type and engine code letter from the VIN. Ask them what the correct ECM is and if they have any in stock. For the 82 Camaros the CrossFire engine code was "7" in 8th position of the VIN. Your engine code letter/number will also be in the 8th position of the VIN. Make sure you have the correct engine code when you talk to the stores about a replacement ECM.

Here are two pictures of my ECM. The first has the service number, which is what AutoZone and the others stores are looking for. In the bottom center of the second picture is the PROM chip. It is replaceable, so that one ECM could be used in several different body types with different engines.

Dave

Jproz1167

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Ive used a 84 vette ecm in a 83 cfi car made it run much stronger

sofakingdom

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CFI, when you boil it down to its basics, is nothing but a simple speed-density FI with TBI.... the only twist is, it has 2 TBs. And even that is pretty minor.

When there were still a few of those cars left in existence, people used to talk about getting a newer ECM, such as out of a 88-92 TBI car. (preferably from the years before VATS... I forget when that was introduced) It all hooks RIGHT UP if you re-pin the harness appropriately, which is probably easiest by just cutting the late model ECM connector out of a car and splicing it onto your existing wiring. Obviously you need the service manual or similar documentation for both cars, so you know which wires are which. Not hard to obtain. You have all the same components... TPS, MAP sensor, CTS, O2 sensor, etc.; NO DIFFERENT from the later model cars, except that the injector wiring out under the hood is a different shape. The wire colors are even the same, for the most part. But all the parts are the same, work the same way and interchange directly.

For that matter, www.turbocity.com might still even offer a "kit" for doing this; they used to, a LONG time ago. They had various other "upgrade" parts for CFI as well.

Using the newer ECM means you get PROM programmability, the faster data link, altogether faster processing, etc.

I WOULD NOT bother with GM. They have basically forgotten how to service any cars older than about 7 years, and they don't keep service info for them. You're probably wasting your time even thinking about asking them a question. Your car is officially an antique in some states already; new car dealers aren't going to be of any help.

Ronny

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another option is to modify the newer ECU of choice(research this on choice) so it will mate up to your cars wire harness. that way you need only plug the ECU in and not butcher harness. see speedtronics.net for this service

coolram62

iTrader: (2)

The ECM was changed from '82's '550.The correct ECM for the '83 CFI is the '6026('6025 can be used).The '84 Vette CFI L83/Auto combo also used the same ECM(as Jproz mentined).You have to use the PROM for the correct appilication.But as sofakingdom and Ronny mentioned you can upgrade to a later ECM such as the '7747.

n1ffer

Hey everyone - thanks for the replies. I have an update.

I ordered a 6026 ECM and used the chip that was in the ECM that I was unsure about.

I didn't have much expectation, but it actually made the car run almost perfectly. I know I have low fuel pressure and will be replacing the pump with an '85 up TPI pump, but other than a weak WOT, during normal driving it drives almost perfectly. A HUGE improvement from where is was. It doesn't stumble on itself or surge like it used to and runs much more smoothly.

Hopefully a new fuel pump and all will be perfect.

Thanks again to all, I appreciate the info.

KITT1983

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any updates

n1ffer

As far as updates - I haven't replaced the fuel pump yet. It is parked for the winter and I hope to get the pump replaced next month or April.

It is so bad now that the car will literally stall at highway speeds. Still ok light to light, but need to get it changed.

I will post once the pump is changed. Thanks!

KITT1983

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Any updates?

chazman

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After chasing electronic gremlins for weeks and replacing the passenger side injector on my former '83 CFI, the culprit was the ECM, which looked like this after opening it up:








I replaced it with a rebuilt unit and all was good.

KITT1983

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the links are down