Engine Misfire

[scaryjerry33]

Can anyone give me some tips on why my 2002 3.8L Firebird"s 3rd cylinder is not fireing? I changed plugs, checked conduction on cables, checked the injecters, and replaced the coil. I hooked it up to the computer and it says error PO303 Cylinder 3 misfire. Does anyone know what else I can do?

Thanks, Jerry

[Morley]

Cam position sensor, maybe?

[MrWrongsalive]

I was working on my buddy's 1998 Camaro with a 3.8L and his problem is a misfire. We ran the scanner on it and it came back that the crank position sensor is bad and cylinder #3 is misfiring. You can definately smell the fuel at the exhaust and the check engine light is flashing indicating a catalyst damaging misfire. I changed the crank position sensor, and it had no effect. I pulled the plug which was wet with fuel and noticed that at 120k on the odometer the plugs were origional. We are definately doing the plugs tomorrow and I have some spare DIS coils laying around so I should know more tomorrow. I'm gonna start off with a compression test to make sure the cylinder isn't messed up, and then go from there. He told me that he put gas in his car and immediately there after the misfiring began. Hopefully I'm not stuck on it too long. I'll try to post my results when I get done tomorrow. Let me know if you found anything with your car.

SOLUTION: We did some more digging and discovered that the number three plug was not firing. Afterwards we ohmed out the plug wires and #3 had infinite resistance. New wires and plugs and the car runs like a champ.