2008 Ford F150 P0352 and P1000 Fault Code: Hard Starting, Rough Idle - Diagnosis and Fixes
I own a 2008 Ford F150 with a 4.2L V8 engine. After driving normally in the city for several hours, I parked it for 45 minutes. When attempting to restart, the truck was extremely difficult to start and ran very roughly once it did. I used an OBD2 scanner and found two fault codes: P0352 and P1000. - P0352 indicates a misfire detected in cylinder 3 or 4 (specifically, coil pack failure). - P1000 means the drive cycle test was not completed — this typically occurs when the engine hasn't run long enough or under proper conditions to complete diagnostics. I replaced the coil pack (Type 2, not COP) as it showed visible cracks. After installation, no improvement in performance. I double-checked that the spark plug wires were correctly wired and confirmed there was no miswiring. I tested for spark at all cylinders — cylinders #3 and #4 showed no spark. I swapped the plug wires with known-good ones, but the issue persisted. I then tested power to the coil pack: - With connector unplugged and key on: 12V on violet/white wire (power), 0V on the other three wires (signal/control). - With connector plugged in and key on: all four wires showed 12V. This suggests a potential issue with the coil pack or wiring harness, but I replaced it with a second new coil — no change in symptoms. The engine still runs roughly. However, after completing a drive cycle test, the OBD2 scanner reported all systems as normal. I'm now looking for further troubleshooting steps to identify whether this is a faulty PCM, intermittent wiring, or another underlying issue before considering professional repair or PCM replacement. Any suggestions or insights would be greatly appreciated.
Update: I checked the spark plugs and gap prior to installing the second coil — they appeared in good condition. I replaced them afterward just to rule out any plug-related issues. The plug wires have approximately 20,000 miles on them and passed a thorough inspection for wear or damage. I tested continuity from the PCM to each coil pack using an ohmmeter — all readings showed proper continuity. I removed the PCM module and inspected it for physical damage, bent pins, or corrosion. No visible issues were found. My goal is to eliminate as many potential causes as possible before taking it to a shop or replacing the PCM. Any additional diagnostics would be helpful.