I have a '05 XLT Screw 11,000 miles and Just wondering if anyone else had the same problem. I noticed the truck not running right like it was missfiring not bad but noticable. Then today it really got worse the check engine light flickered on and off then when I checked it with my meter and it came up with a P0171 Lean fuel, and a P0303 misfire Cylinder 3. I'm running 87 octane in right now. I'm new to Ford products being this is my first truck and my first Ford, just want to know what might of caused this misfire in the engine. Please help.

 

I did a little homework and found a TSB on this issue.

Technical Service Bulletins Summary

Make: FORD
Model: F-150
Year: 2005
Type: TRUCK
Service Bulletin Number: 041601
NHTSA Item Number: 10018745
Summary Description:
WDS COP KIT DIAGNOSTIC TIP - COIL ON PLUG (COP) IGNITION SYSTEMS - ENGINE MISFIRE OR ROUGH RUNNING. *TT


Taking it over to the dealer to fix the problem, Thought it might of been something I did to the truck to cause the problem, guess not.

 

I had a misfire on my 05 F150 FX4 it turned out to be a bad plug.It took them 3 hours to change plug and do 25000 mile service but it runs perfect now

 

Just got the truck back from dealer and it ended up being a bad fuel injector not a coil issue. The truck runs great now.