Thread: Misfire in cylinder #1

Just got back from a 1,000+ mile road trip for a funeral. About 150 miles into the trip the "service engine soon" (SES) light came on, felt like the car was mis-firing but due to time constraints couldn't stop to fix it. After arriving at destination took it to mechanic to verify and indeed it was a misfire. Changed plugs and wires and cleared error code. Engine still shook a little but no SES light. Headed home, about 250 miles in SES light came on again. Upon getting home checked OBD code still showing misfire in cylinder #1. Also just this once car had trouble starting and needed a jump, also wife (her car) tells me "oh yeah, had trouble starting a few weeks ago and when I had the oil changed they said the battery was showing low." Any other ideas what could be causing misfire? I thought maybe coil but read that I should get misfires on both cylinders that are attached to that coil also tested with multimeter and didn't show any problems. Also as far as I can see battery tests fine with multimeter as well. Other thought is it may be fuel injector. Thanks for any help.

99 Grand Prix 3.8L V6
143,000 miles

Originally Posted by Explicit_Spade

Bad coil pack or ICM for the missfire.
Bad alternator for the low/not charging battery.

Thought bad alternator as well, but multimeter shows volts at 14+ while running

Thanks for all your replies, swapped coils and it stayed on cylinder #1. Next step is to add some Techron to see if it's just a dirty injector, currently waiting for my tank to empty which takes about 2 weeks since I'm only 3 miles from work.

It's been a few months but I'm still having issues, but I may have some more clues, earlier this week I found that I had a problem where the car starts "bucking" at 4k RPM, and it's exactly at 4K, I can rev it up to that point with no issues but right at 4k it bucks, once to the point of stalling out. I bought some MAF cleaner but still had the same problem. Before I invest in a new MAF I thought I'd check for vacuum leaks as suggested above. Is there a common area that has problems on this car? Oh I also had the fuel pressure checked and there's no issue there. The OBD code is P0102. Also here's a video of what the same thing my car is doing after driving (not when first started) intake manifold leak...00 Grand prix GT - YouTube
Thanks again for any help!

Originally Posted by sseilmnop

Misfires on cylinder 1 & 2 could be a vacuum leak from hose on the front nipple of LIM, by the coolant elbow This hose feeds a bunch of stuff. Check the vacuum lines from this port.

OK, I tested for vacuum leak with carb cleaner and nothing that I could hear. So I cleared the codes and drove around, I couldn't get the light to come on but I did get a pending code of P0102 again. Then used the monitoring feature of the scanner and saw that the air flow was staying right at .16%, no change at all when revving. Everything seems to point to the MAF sensor but I'm hesitant to spend the money w/o ruling out everything else.

After stalling many times today I changed the MAF which seems to have fixed that issue, but the misfire is still happening, also heard a squealing from the alternator. In order to make sure it wasn't a broken bearing I removed the belt and was able to hand turn the alternator so I think that is not an issue (maybe squealing is from belt, but sounded like it was from the alternator). Anyway down by coolant elbow, near the tension release for the belt I saw this wire sticking out of the harness (see pictures) I thought it was a broken/melted wire and I was looking for the other side but it doesn't exist, is this wire some sort of ground that has fallen off, or just a random stray wire?

Yep, that should have been connected to a ring terminal that is a ground on one of the studs that holds on the coil pack bracket.

I assume you're referring to these studs (this is not my car in the picture, just one i found on the internet)