02 GrandPrix New member

[02grandprix1980]

I have a 02 GrandPrix GT It has a miss on the #6 cylinder and I've done plugs,wires,fuel injector,coil and it's still missing it will start up fine seems to idle ok at about 600/700 rpm's.But once i give it gas it boggs down bad and when i let off the engine starts jumping around like it's missing like crazy on #6 then it stops and runs ok at idle.Now i checked the spark plugs there all fine but #6 plug had alot of carbon built up on it so i cleaned it cause there brand new plugs like 2 weeks ago.I've done some research and i'm starting to lean towards its a bad cat with it being clogged if it is i read that the back pressure can cause a misfire on a single cylinder.Well if anybody has had this problem or if you have another solution please let me know.Also the car is not drivable once you put it in gear you can tell it's missing and it wont go over 40mph.Thanks

 

[TheOtherNick]

Cat will cause a miss on all cylinders. Do a cylinder leak down test.

 

[fishman517]

Have you checked the fuel injector? I had issues with my Turbo Grand Prix and it ended up being injectors in two cylinders, in fact they ohmed out good and it wasn't until I removed them and fired them with a tester at running pressure that I found one was leaking and had a terrible spray pattern and the other one wouldn't spray at all. Talk about a head scratcher, I'm glad that's all behind me. Good luck!