Hi everyone, I've got a 2004 f-150 fx4, with 5.4 3 valve engine. For just over a year now it's been back firing, and has no power when you step on it. I've replaced the fpdm, frps, fuel pump, plugs,and fuel filter, and changed the intake gaskets. It still has the same codes no matter what I do. The codes are 171,174,190,191,301,305,316,300pd. Can someone help?

 

Hi and welcome!

How many miles on the truck?

That series of codes still points to a fuel delivery problem despite what you have changed, imho. Have you checked the entire fuel line and fuel rail for any sort of blockage? There is a chance that one of the items changed was itself defective. Rare but it can happen.

Have the injectors tested.


Other stuff.

What brand are the plugs? Were they R&R'd properly ( new boots, fresh dielectric, proper torque)?

What aboot the COPS? May need testing / replacement

How old are the front O2's?

Check the cats for clogging.


Chronic misfiring, over time, will ruin your cats due to dumped raw fuel. And contaminate the oil in the crankcase with same, while washing down the cylinder walls. If you've let this go for a year, expect further issues. Not good.

good luck

MGD

EDIT - this is probably not the best forum section - ask a Mod to move it to V8 Engines for more exposure - the real experts live there, lol.

 

Thanks ,the truck has 116k, and I used the factory plugs in it.How do you test the injectors?

 

Hi.

So - Motorcraft SP-515's, new boots and proper dielectric application.

Both injectors (and COPs) need to be tested by a properly equipped facility.

You can do a homemade leakage test ( it's in the How-To section) but I don't think that's the problem.

good luck.

MGD