I have a 01 f150 lariat 4 wheel drive with the 5.4.It first gave a code saying the #8 coil was bad.I replaced it and it ran good for a few days and then the valves started rattling and it started skipping and hesitating.It runs ok for a few miles and then it starts cutting up.The CEL isnt coming on and the code scanner shows no data.I have replaced the plugs,plug boots,fuel filter,MAF sensor,PCV valve,and cleaned the throttle body and still no luck.I've taken it to 3 different mechanics and none of them can fix it.The fuel pressure has been checked also.Sorry for rambling but Im at my wits end.

 

Did any of the mechanics check the performance of the #8 injector?

 

Im not sure.I was thinking it may have something to do with the injectors but all of the mechanics tell me thats not the problem.

 

You may want to have a compression check done and also a leak down test.

 

It doesnt run bad all the time.I had the fuel injection cleaned out Friday and it ran good for about 10 miles and then it started running like crap again.The next day it ran good for about 5 miles and then it started rattling and missing.So do you still recommend a compression and leakdown test with these things being said?

 

Cancel on the compression tests. Sounds like the coil in the injector is going bad and the problem shows up when it gets hot.

 

I have a 00' model doing the same thing. im taking it tomorrow to get it fixed (hopefully). but my mechanic told me it could be a coil problem. i have had a truck in the past to this to me and it wound up being a bad spark plug. the porsalin on the plug was cracked. and when the engine would warm up, it would expand and start missing when i would give it gas.

 

The truck idles fine and never misses a bit when it is in park.It only misses and rattles when it is under a load.Is there any way to test the injectors?

 

Was it rattling all the time before you got injectors cleaned? Have you checked fuel pressure at warmed up truck?

 

Yes,it was rattling before the injectors were cleaned and the pressure has been checked with the truck warmed up.Somebody said the catalytic converters might be stopped up but somebody else said it would run bad all the time if that was the case.