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2005 Neon Missfire Code P0304 - After Replacing Plugs, Wires, Injector, and Coil Pack

Model: neon Fault Code: P0300 Posted: 2007-02-16 17:08

I own a 2005 Neon with 44,000 miles that consistently shows a misfire on cylinder 4 (P0304). I've already replaced the spark plugs, ignition wires, fuel injector, and coil pack. Despite these changes, the check engine light remains on and the vehicle occasionally runs rough. It may run smoothly for several days before the issue returns. I recently installed platinum-tipped plugs gap-adjusted to specification. What should I do next to resolve this persistent misfire?

Related fault codes
P0300P0301
Comments (4)
Anonymous 2007-02-18 18:16

Remove the current platinum spark plugs and install the OEM-spec Champion plugs as recommended in the service manual.

Anonymous 2007-02-26 19:48

Inspect for vacuum leaks around cylinder 4 using carburetor cleaner. Pay close attention to idle behavior when spraying; a noticeable change may indicate a leak.

Anonymous 2007-03-03 11:32

Mohawkmtrs wrote: Remove the current platinum spark plugs and install the OEM-spec Champion plugs as recommended in the service manual. I removed the platinum plugs today and installed the Champion plugs specified by the factory. The misfire has not returned; the vehicle is now going back to school tomorrow for a test, so I'll update with results.

Anonymous 2007-03-04 13:49

Good luck — please share your outcome if you're able to test the car after the repair.