2003 Ford F150 P0301 Code: Idle Rough, Clean Plug - Possible Coil or Vacuum Leak?
Hello, I'm experiencing a P0301 fault code on my 2003 Ford F150 with a 4.6L engine. The vehicle idles roughly despite the #1 spark plug appearing clean, dry, and in good condition. After removing the injector connector, there was no improvement in idle performance. If there were no sparks, the plug would typically be wet — which it isn't — suggesting either a faulty coil or an issue with fuel delivery. Could low fuel pressure be contributing? Since cylinder #1 is farthest from the fuel pump, could that affect performance? What should the ideal fuel pressure be for this setup? Any other potential causes or troubleshooting steps? Thanks for your insights.
The most likely cause is a faulty spark plug coil rather than a bad injector. A vacuum leak should also be considered as a contributing factor.