1989 Firebird Formula ECM/Prom Question - Third Generation F-Body Message Boards

bobscar · 07-06-2009, 06:17 PM

I have a 1989 Firebird Formula with a tune port fuel injected 305 engine and an automatic transmission. The ECM and prom need to be replaced. The ECM part number is 1227165 and the prom part number is 16133473.

I cannot seem to find the stock prom anywhere. I have been able to find an ECM (part number 1227165) with a high performance chip. I've been told they came from a Camaro. Here's the question. Will this ECM with the performance chip be compatible with the Firebird?

Any help would be appreciated.

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RBob · 07-06-2009, 06:36 PM

When replacing the ECM the stock MEMCAL is usually used. IOW, the ECM when purchased does not have a MEMCAL. So the MEMCAL from the original ECM is used in the new ECM. They plug right in under the small cover. Check the sticky's above for pictures of a MEMCAL.

As for using a performance chip, it depends. It may work OK, it may not work OK. The reason for the uncertainty is that no one other then the tuner of the chip knows what was changed.

From what I have seen of the MAF f-body TPI cars, GM had a different calibration for the Firebird vs. the Camaro. Although I don't know why. It may be a minor item. All you can do is to try the MEMCAL and see if it is OK.

Note that you should not use a stick PROM (calibration) on an auto vehicle. This has to do with the TCC lockup.

RBob.

bobscar · 07-06-2009, 08:44 PM

It appears I mixed up the terminology a bit. Thanks for the clarification.

Because I've been told both the ECM and MEMCAL are bad, it sounds like I should simply try to find a stock MEMCAL (Part #16133473) and avoid any potential issues. However, finding the stock MEMCAL is proving to be more challenging than anticipated. Any guidance in finding one would be appreciated.

RBob · 07-07-2009, 09:25 AM

GM has been discontinuing MEMCALs. You can try places such as GmPartsDirect, or some of the sponsers here for a used one. The classifieds are another possibility.

Usually the CALPAK portion of a MEMCAL never goes bad. It is the PROM that can go bad and/or be changed for a different calibration. If you know someone that can burn a PROM a stock calibration can be burned into it.

If you have the ECM plug in the MEMCAL you have now. Then look for the SES blink: at key-on, engine-off the SES should turn on, blink off, then turn on solid. To repeat the test key-off for at least 10 seconds.

The blink off is the important portion of the test. It verifies that the ECM is running from the PROM. And not in limp mode.

RBob.