1996 3.1L Issue [Archive] - GrandAmGT.com Forum

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Rottie
10-16-2012, 05:05 AM
First I'd like to say thanks in advance. Forums like this are always a good place to find information and solutions to problems you may never have thought of. I hope you can all help me.....

The car is a 1996 Grand Am SE with a 3.1L/auto. 118,xxx miles.

Car was running fine, pulled off the freeway and it started. A very rough idle and almost no power. Flashing SES.

So the car has a serious misfire issue, however it's not a stadard misfire. The car is actually firing ALL cylinders and firing ALL injectors every time it fires any plug. So when it should fire plug 1/injector 1, it fires all 6 plugs/injectors. Now from what I understand this is some sort of limp mode the car can go into when it doesn't know when TDC is.

The following items have been replaced: both O2 sensors, plugs, wires, coils, ignition module, MAP, camshaft position sensor, and both crankshaft position sensors. PCM has been swapped as a last resort as well. Nothing has changed the way the car runs.

Cannot find any vacuum leaks. Fuel pressure goes to 47 and holds, retains pressure when the car is shut off. Injectors are all firing and look even. All plug wires/plugs are firing. Checked ground wires, checked as much wiring as I could for breaks/deterioration/exposed wires.

It's got me pretty much beaten down. Any ideas as to the cause?

unchained_01
10-16-2012, 09:42 AM
i would pull the PCM/ECM and have it checked

Rottie
10-16-2012, 09:44 AM
Yep, thought of that too. Got another 96 PCM and it runs the exact same way.

It's got to be something in the wiring at this point.

Is there a common wiring problem anywhere?