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2002 Pontiac 3800 V6 P0306 Misfire: Diagnosing After Replacing Fuel Pump, Plugs, MAF, Coil Pack, Injector and Filter

Model: 2002 Pontiac 3800 Fault Code: P0306 Posted: 2014-04-28 13:13

I'm experiencing a persistent P0306 misfire code on my 2002 Pontiac 3800 V6 engine. I've already replaced the fuel pump wires, spark plugs (AC Delco), MAF sensor, coil pack, fuel injector, and fuel filter. Despite these changes, the vehicle continues to misfire with the same P0306 code. Compression tests show consistent 140 psi across all cylinders. I also recently replaced the ECM, but the issue persists. I'm at a loss as to what could be causing this ongoing problem. Any insights or diagnostic steps would be greatly appreciated.

Related fault codes

P0306

Comments (2)

Anonymous 2014-04-28 13:51

Is P0306 the only fault code present? Have you verified spark at cylinder #6 using a spark tester? The plug is an AC Delco model — this matters for compatibility. Is the fuel injector pulsing correctly? Use a Noid light to check: flashing indicates proper pulse, steady or no flash suggests failure. Is your vehicle stock (no modifications)? This is important as modifications can affect misfire patterns. Cylinder #6 is located on the rear driver's side — correct?

Anonymous 2014-04-28 15:38

Yes, P0300 to P0309 are the only codes present. I've confirmed that cylinder #6 is firing and I'm using AC Delco spark plugs. I'll get a Noid light soon to check injector pulsing and will update with my findings.