Pontiac Repair: 1992 grand am pcm problems, voltage drop test, google search

Question
QUESTION: I have a 1992 pontiac grand am 104,000 the pcm was replaced and now it is gone out again the car will only run on 2 cylinders what would cause it to keep killing half of the pcm so that it only runs on 2 cylinders it's getting fuel to all 4 but no spark on 2 cylinders please help thanks a lot for your time

ANSWER: Hey Josh:

are you sure it's a PCM issue and not an ignition module and or coil problem? It's odd for as PCM on that car to go bad. the PCM that was replaces was it an after market one or and Original equipment part? how long did the replace ment unit last before you had this issue crop up again?


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QUESTION: the frist one was oem and it ran for about 150 miles i let it sit for two days and then it started acting the the cat was pluged it cheryed up so i cut it off and put in a straight pipe.it has all new parts that test good ignition control module is new,coils are good. The ignition module is what started this all it went bad and it hasnt been the same since.it will run but not good

Answer
Okay to re trace your steps. the ignition module went bad and you replaced it. It ran okay but then the PCM went bad. the cat was glowing red? that was from all the unburned fuel from the misfire on 2 cylinders. The replaced pcm then went bad? I would do this. first off you need a service manual. make sure you don't have any open ckts between the ignition module and the PCM. I belive on those old cars there is one trigger wire for each coil going from the PCM to the module. make sure you don't have high resistance in them or open ckts. Make sure all the grounds going to the PCM are clan and tight and you indeed have a good grounds at the pcm. do you know how to do a voltage drop test? If not do a google search and do a drop on each of the grounds and power feeds to the pcm. if all the wiring is good then I would try a new igniton module (OEM) not aftermarket and same with the PCM. One last thing to check is the coil that is not firing. the primary side of the coil should have more then say 2 ohms. the secondary side should be between 5000-7000 Ohms. compair the reading to the "good" coil. good luck :-}