[Formula757fixer]

Anyone have any good suggestions for a reliable source for a replacement PCM for 98 WS6? Or would it be better to send mine in to someone for a complete reprogram/update? Also why cant the PCM be reprogrammed while still in my car? (or can it) TIA

 

[Injuneer]

Do you need a ”replacement“ because the current PCM is damaged/inoperative?

Or are you looking for one with a upgraded or custom tune? If it's the tune, your existing PCM can be programmed while in the car, or by a mail-order tuner. Is the engine stock or modified?

 

[Formula757fixer]

I need a replacement as this one is constantly causing a misfire in number 7 cylinder. I've replaced everything on the outside that could cause it and even had a pro look at it for a week and finally agreed with me. Everything is stock minus the injectors and the obvious that I've changed.

 

[Injuneer]

You have non-stock injectors? And what is the extent of “the obvious that I've changed”? Are those performance upgrades?

Have you done a compression test?

PCM failures are extremely rare.

 

[Formula757fixer]

I changed the injectors as the hope to a fix. It didn't. Neither did the plugs, wires, #7 coil change or the coolant temp sensor. They weren't performance upgrades just a hooe to a fix. No no compression test, but its1 always #7 and it's random. Could be a day in between or could be a week. And when it does do it it last 10 mins or less and back to normal.

 

[Injuneer]

We’re you getting a fault code for #7 injector?

Were you able to used a code scanner with GM “enhanced parameters”? Is that how you accessed the misfire count for #7?

Not sure why I'm asking these questions since you've already made up your mind it's probably the PCM.

 

[Formula757fixer]

P307

 

[1993TransAm]

I agree with Fred on trying a compression test with the cylinder at issue before you condemn the PCM.

 

[Formula757fixer]

Certainly not disagreeing with that, but the fact that it happens randomly and at startup, what does that mean?

 

[Injuneer]

P0307 indicates a misfire on #7, doesn’t indicate the cause.

Random misfire due to compression - faulty lifter, sticky valve