2003 f150 FX4 5.4L
changed all plugs yesterday with motorcraft. the truck ran fine all day yesterday and today then tonight wy wife drove it about 200 miles and it started chugging and barely ran, and no CEL.


EDIT: parts store pulled a code, miss fire #4, what is going to cause a misfire?

 

I have had this problem after changing out coil packs. You should make sure the wires are plugged securely into the coil pack. If that doesn’t fix it you will probably need to replace the coil pack.

Good Luck.
Gabe

 

Have you checked to see if all of your wires are properly seated? Did you Gap them to the proper gap? I had a recent experience with MotorCraft plugs and will never use them again. I had MotorCraft Platinums with only around 45k miles on them and my truck started chugging under pressure and my check engine light came on so I pulled a plug to see what it looked like and it was garbage, and all the rest of them came out right after than one did.

 

I doubt it's the plugs so much as what the plugs are screwed into, your the first and only person I ever heard complain about motorcraft plugs in a ford

when you replaced the plug in number 4 did you notice any coolant leaking from the intake or heater hoses? that is usually the reason number 4 starts to misfire other then that you might have cracked a plug putting it in or you have a bad coil, move the coil to a different hole and see if the mis follows the coil

 

[quote=fordtech08;8375705]I doubt it's the plugs so much as what the plugs are screwed into, your the first and only person I ever heard complain about motorcraft plugs in a ford

What are you trying to say? That something is wrong with my motor?

 

[quote=bigredneck47240;8376038]the way the plug looks is an indication of the engine, be it running lean, running rich, burning oil or coolant, so yes I'm saying your engine isn't new anymore and the plugs are an indication of that