Hey guys I have a 2000 Grand Prix GTP coupe. Ok so when I first bought it I noticed it had a small miss, then I drove it for about 2 weeks and the miss got very, very bad! I pulled the spark plugs and Plug #1 on the front row of cylinders was finger loose and it was missing the electrode and part of the middle piece. I pulled all the other plugs and they were at least all in one piece there but what I believe to be the original AC/Delco iridium spark plugs! My car has 155,000 miles on it by the way. So I do a compression check on cylinder #1 and guess what? 0 psi. Shoot. All the other cylinders were in range. So me and my dad pull of everything to get the head off and go to the junkyard to get a used one. Then we took it to some shop to have it boiled and checked for cracks then had the seats done and new valves and valve stem seals put in. Put it all back together with Autolite Platinum plugs. Runs really good for about 400 miles then it started missing again. Pulled the plugs and they all looked like complete crap! Cylinder #2 in the back was missing the electrode completely and Cylinder #5 was missing part of the electrode and all the other ones were bent way out and looked like they were about to give. So I did another compression check and what a relief all the cylinders were good. This time we put AC/Delco iridium plugs in and I just got done installing that 4" custom FWI. It ran good for about an hour (BTW My gas mileage went from 20mpg to 18.3mpg after that FWI) and then when I brought it home and listened to the exhaust it sounds like its missing again!!! My dad has a scanner so that will be the next thing I do and I'll post the results.
Thanks for any help!
