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P0304 Fault on 2000 Ford Expedition with 5.4L Engine at 145,000 Miles

Model: 2000 Ford Expedition Fault Code: P0304 Posted: 2007-12-13 19:14

I'm experiencing a persistent P0304 cylinder 4 misfire code on my 2000 Ford Expedition with a 5.4L V8 engine, currently at 145,000 miles. I recently replaced the coil pack (COP) and spark plug, but after the replacement, several new diagnostic codes appeared—possibly due to improper installation or component incompatibility. I've since replaced the PCV valve and cleaned the MAF sensor, yet the P0304 code has returned. The original spark plug showed a pinkish electrode color, indicating possible overheating or combustion issues. Spark testing appears normal, but I'm unsure what to check next. How can I properly diagnose the fuel injector? Any recommendations for troubleshooting the #4 cylinder injector? bea

Related fault codes
P0304
Comments (2)
Anonymous 2007-12-14 16:15

A good diagnostic step would be to swap the #4 fuel injector with a known-good injector from another cylinder. If the P0304 code moves to the new cylinder or disappears, it strongly indicates a faulty injector.

Anonymous 2007-12-15 11:07

Thanks for the suggestion—very helpful. Is removing the fuel rail and accessing the injectors on this model straightforward? I'm looking for a step-by-step guide to ensure I don't damage any components during the process. bea