Hey I have a 2007 Pontiac Grand Prix GXP I changed spark plugs wires and coils was wondering what else could make it misfire. Also car has tap shift options which recently stopped working and ideas as to what the problem is?
Do you know which cylinder is misfiring? Need to determine that. Having an auto parts place read your codes will be a good start. Then you need to run it for a bit and pull the plug. If it’s wet with gas your not getting fire. If it’s dry then that cylinder isn’t getting fuel. Could be an injector issue or injector pulse issue. Could be broken or bad cam lobe/rocker/valve stuck etc.... Start by determining cylinder and go from there. Do a compression test on it. Check the plug etc...
In addition if engine isn’t running correctly the tap shift feature I believe gets disabled. Get misfire taken care of first.
cylinder 4
Rin a compression test on it. That will let you know if the rings, cam and valves are
Ok on that cylinder.
check out the misfire troubleshooting in our FAQ
