2004 F150 5.4 V8 Triton - 202K miles -

I keep getting the error code P0358 - Coil issue -

Changed out all spark plugs - New Coil Pack on # 8 - Still have the code

Swapped out the coil pack to another cylinder - Misfire did NOT follow.

Whats ailing me is the misfire is only at Idle - Which does not make sense as most misfires start when the vehicle is under a load - not at idle only.

I will say that the oil pu screen had gotten clogged - it's been fixed but I am running 15W Rotella which I was told was better for cleaning the engine than a chemical engine flush.

Need some help - I was already charge $1300 for the sparkplugs coil pack and a specialy tool that the shop did NOT own - (yes I got shafted without the vasoline)

Any thoughts to help me diagnose this and a shop in the DFW area that acutally KNOWS these engines?

Tired of being female and "trusting" the mechanic.

 

15W40 is too thick for these engines. 5W30 or 10W30 is the max you should go with these engines.

 

That is not what that fault code means. The P0358 code means there is a CIRCUIT FAULT with the #8 coil. Coil, PCM and wiring harness concerns are all on the list of possibilities.

 

Yep, inspect the wire connector maybe it's broke corroded etc.

 

An 04 most likely has brittle plastic clip broken. Then the little rubber insulator inside the COP clip pushes it up till it doesn't make (or makes flaky) contact.

Don't feel too bad. I once climbed over a fence and broke a branch off a tree, wedged it between heater hoses and top of #8 COP connector to make it 300 miles home without an exact type misfire.