Back story, few months back october i want to say had a bad ignition modual, was not firing on coil location for cyl #1 & #4 replaced coil and nothing replace ignition control modual and it was great!

Fast forward to friday leave work, i hit a redlight and while waiting for the green it starts missing bad, so pull of into a gas station it's back to normal, thought it was odd checked my conections at the coils and plugs all where fine

Drive to the g/f's parents place, we go out that night and car sits over night, next morning go leave it's fine, stop by my parents to drop my son off come back out to it missing bad again,

Seems to start and run fine when stone cold, but give it 5 min of warm up starts missing again,


I'm kind of at a loss here, i will pull it and run up to the parts store and hope to get it warrentied, (cant find my reciept but is under an account)

But anything anyone can think of that might be causing the premature failure i would like to hear it

 

IDM man don't rule out a failing MAF

 

But would a failing MAF tell the pcm to kill a coil pack on the icm, i can pull the plugs off the 1/4 coil and not get shocked lol

 

Check your ground under the ICM bracket and all your ICM wires

 

donno if it makes a differance but did run a jumper wire from there it bolts directly to another existing body ground, no change

Thanks for your help i do appreciated it,

 

First, most parts stores can test the ICM. Second, I assume it's not throwing codes? Third, it could be the MAF. When the MAF screws up and gives the car the wrong data, it causes all kinds of crazy stuff.
The symptoms you describe is what happened to a friend's Bonneville with the L36, just add the occasional stall to the symptom list (but their car had CEL data). As a work around until a replacement MAF arrived from RockAuto, we just disconnected the MAF.

 

Only cel data is p0300 multiple missfire

 

Hmm, I'd probably explore these items in this order:
- Check for any damaged or loose vac lines. Perhaps a part has a little dry rot going on making a vac leak and weird performance.
- Get the ICM checked out at a parts store (I've only seen one fail once before, so they are rare, but a free check up is pretty quick and easy to haul it into the parts store).
- Next time the car acts up, pull over, turn it off, unplug the MAF (it will throw a code for sure, but it may quit mis-behaving which does suggest a MAF and MAF cleaning might be the first step before a costly replacement).
- Clean up the IAC, make sure it's not gummed up.
- My limited experience with fuel pumps is they fail, the car stalls, done. It may restart once or twice, but you are pretty much over real fast (it does not mis-fire). BUT, it might be worth looking up possible tests for a fuel pump.

Personally, I don't know why, but my gut wants to say MAF.

EDIT - I know you recently did some exhaust work. I believe part of that was replacing the cat? If so, when the car mis-behaves, do a visual on the cat, pull over somewhere safe, do not turn the car off, look under it at the cat. If the cat is red, you have an exhaust clog.

 

FYI - Justin I e-mailed you a couple PDFs that I hope help (I have not read them but thought they may be of assistance).

 

Next time you do a warm-start and it fails, unplug the MAF and then try to start it again.

That's a pretty easy test for the MAF sensor