Hi guys,

Got an issue that no one seems to be able to put their finder on.

I have a 2005 F150 Lariat 4x4 with a 5.4L 3v V8. The truck is running great at idle and under normal driving conditions. The issue is that between 4,000 and 5,000 RPMs I am experiencing either or both a cylinder 1 and/or 3 misfire (PO301 and PO303).

Here is a list of what I've done.

Timing chain
8 new plugs
8 new coils
New fuel injectors on 1 and 3
New PCM
Compression checked out at 150 psi
Had a muffler guy test the cats their good

What am I missing? Why would a truck only misfire at higher RPMs and run perfect any other time?

Cam sesors, crank sensor, EGR valve??? Anything? I got a code this morning that I have not pulled before PO351. Has to do with the primary circuit to Coil #1.

I would appreciate any and all feedback. Thank y'all in advance for your help.

Travis

 

Where did you get the COPs from?
What kind of spark plugs did you install?
Check the plug holes for moisture.

 

COPs and plugs are Mortorcraft, straight from Ford.

No moisture in the plug hole.

Thanks for the reply. Any and all suggestions are very welcome and potentially helpful. Much appreciated.

Travis