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2002 Ford F-150 4.6L V8: Multiple Spark Coil Faults (P0354, P0355, P0356, P0358) with Random Cylinder Misfires

Model: 2002 F-150 4.6L Fault Code: P0300 Posted: 2017-04-12 11:57

Vehicle: 2002 Ford F-150, 4.6L Triton V8 engine Issue: Recently experienced four OBD-II fault codes simultaneously: P0354, P0355, P0356, and P0358. The engine lost power under load but idled smoothly when in gear. A rough idle was observed in park. After sitting for approximately two hours, the truck resumed normal operation and is currently running fine. I suspect that four spark coils failing at once is highly unlikely, so I'm considering alternative causes. While the ECM (or PCM) failure is a possibility, I lack the electrical expertise to verify such an issue directly. Key details: - Vehicle is stock with no aftermarket modifications except for rims. - No additional fault codes are currently present, though a past P0442 code has appeared intermittently. - One spark plug assembly (COP) appears to be aftermarket and differs in color — I am unsure if it's installed on one of the affected cylinders. I plan to inspect all coil connectors for corrosion, loose clips, or bent pins tomorrow. The 8th character of the VIN is 'W', indicating an automatic transmission variant. My primary concerns are: 1. Aftermarket spark plug assemblies (COPs) 2. Loose or degraded connector clips at coil terminals 3. Potential degradation in coil health over time 4. Possible ECM/PCM failure, though this remains speculative due to lack of diagnostic tools Any insights, troubleshooting tips, or known issues related to 4.6L V8 engines with multiple COP faults would be greatly appreciated.

Related fault codes

P0300P0301P0302P0303P0304P0305P0306

Comments (5)

Anonymous 2017-04-12 12:01

Apologies — I meant PCM (Powertrain Control Module), not ECM. Also, no visible damage was found in the wiring harness during inspection, which may help rule out some issues.

Anonymous 2017-04-12 12:33

ECM, PCM, and VCM are often used interchangeably — while ECM failures do occur, they're not among the most common causes of ignition-related faults. Let's avoid jumping to that conclusion. Are there any additional diagnostic codes? For example, P1351? I recommend checking all spark plug connector terminals for tightness, corrosion, and physical damage (bent pins or contacts). Note: The 4.6L V8 uses a Coil Over Plug (COP) system with eight individual coils — not coil packs. PS: Posting the 8th character of the VIN helps identify specific engine variants and known common issues. • 4.6L V8 VIN 6 Automatic • 4.6L V8 VIN 6 Standard • 4.6L V8 VIN W Automatic • 4.6L V8 VIN W Standard

Anonymous 2017-04-13 03:51

Yes, the truck is stock with no aftermarket parts except for rims — just a light joke about that! 😄 No additional fault codes are currently active, though I previously saw a P0442 code that appeared sporadically. I’ve identified one COP as being aftermarket and different in color. However, I’m not yet certain if it’s installed on one of the cylinders flagged by the P035x errors. I’ll be checking all coil connectors tomorrow for signs of corrosion or loose connections. The 8th character of the VIN is 'W', indicating an automatic transmission model. Thank you for your helpful input!

Anonymous 2017-04-13 07:24

Just to confirm — we're looking at the correct spark coils. Connector clips on the coil terminals are a common failure point and are available as replacement parts.

Anonymous 2017-04-20 12:42

Finally getting back to this post after working overtime. I've confirmed that the COP for cylinder #4 is defective — no short circuits were found in any of the other wiring runs. All coil and PCM connector pins appear intact and secure. The truck now runs smoothly, but I'm still puzzled as to why cylinders 5, 6, and 8 were flagged by the fault codes. I did find a faulty clip on cylinder #7’s coil — it wasn’t causing any performance issues, but this is a helpful reminder (thanks, KEV2). It's possible that some of these coils are simply aging or weakening. Without proper diagnostic tools, I can't verify their health directly. Thanks again to Kev2 for your thorough and useful guidance. If you have further suggestions or insights, please share — I’d appreciate it!