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2003 Ford F-150 5.4L P0301 Cylinder 1 Misfire: Diagnosis & Solutions After Replacing Coil, Spark Plug, and Injector

Model: 03 f150 5.4 l Fault Code: P0301 Posted: 2015-01-08 18:08

Hi everyone, I have a 2003 Ford F-150 with a 5.4L V8 engine that's currently throwing a P0301 diagnostic code indicating a cylinder 1 misfire. The truck has accumulated around 185,000 miles and the issue only occurs when idling or at red lights—once I accelerate, the problem disappears. I've already replaced the spark plug, fuel injector, and coil pack, but the P0301 code persists. What should I check next? The misfire seems to be intermittent under light load conditions. I'm looking for reliable troubleshooting steps that focus on mechanical or electrical causes beyond basic component replacement.

Related fault codes
P0301
Comments (8)
Anonymous 2015-01-08 18:34

Perform a wet and dry compression test on cylinder bank 1. A low compression reading during the wet test (with about one ounce of oil added to the cylinder) suggests worn piston rings. If compression remains unchanged after adding oil, it may indicate a head gasket leak or internal valve issues—this would point to a mechanical problem rather than an ignition issue.

Anonymous 2015-01-08 21:28

My mechanic performed a compression test and confirmed that all cylinders show normal readings. This suggests the misfire is not due to low compression, so the root cause may lie elsewhere in the ignition or fuel system.

Anonymous 2015-01-08 21:32

A defective ignition coil remains a possibility—did you use OEM or dealer-grade parts when replacing the coil pack?

Anonymous 2015-01-08 21:33

Check for loose or corroded wiring connections at the coil pack or spark plug harness. Poor electrical contact can cause intermittent misfires, especially under idle conditions.

Anonymous 2015-01-08 21:33

No—I used Borg Warner parts from an O'Reilly auto store. I'm wondering if third-party components might be contributing to the issue.

Anonymous 2015-01-08 21:34

It's possible there’s an electrical fault in the ignition system or sensor circuit. Since the misfire only occurs at idle, it could point to a timing-related or signal-based problem that resolves under load.

Anonymous 2015-01-08 21:40

Try switching the ignition coils between cylinders 1 and 2. If the P0301 code changes to P0302 after swapping, it confirms a faulty coil. If the code remains on cylinder 1, then inspect the connector for corrosion or loose terminals.

Anonymous 2015-01-11 11:13

I own a 2004 Ford F-150 XL with a 4.6L V8 engine. Recently, I've noticed hesitation and rough idling. The check engine light flashes and shows P0301 and P0316 codes. Last time I had this issue, spraying the MAF sensor resolved it temporarily. Should I replace the ignition coil, or is there a more comprehensive diagnosis needed? (Note: This may not directly apply to my 5.4L engine but highlights how sensor-related issues can mimic misfires.)