My wife bought over priced 08 Sebring 2.7 V6 Convertible. Took to mechanic and he just replaced parts the error codes call for. After getting the car back I still ran into problems. Main thing was a misfire cylinder 2. Since I had some time, I swapped out plugs, coil packs, and fuel injector, and I did not move the misfire. Took it back to get compression check and was told that compression was a little low, but I didn’t think to check the readings myself.

Finally, a previous problem showed up, the car overheated, and I finally put in coolant instead of water. After adding the coolant, I decided to check spark plug and found it with a light dry matte black on it. I checked cylinder 6 and concluded that the cylinder 2 plug was because of overheating. I swapped them and had no misfire at all.

So I safely assumed the coolant was a factor and decided that I wanted OE plugs in the car. I installed new OE plugs and what came back, the misfire. So I analyzed the plugs and the NGK was a shorter gap than the OE CHAMPION plugs. I put the NGK back in and no misfire.

why is the gap difference effecting just one cylinder?