New member here, just about out of ideas for a fix. I have a 2004 F150 5.4 3v that will cut out at wot, like it hitting rev limiter but this is around 4500 rpm or so. Normal driving is fine, moderate throttle is fine, shifts fine, no misses or bogging. I bought it with a blown motor so don't know history, I put a reman engine in it when I bought it a while ago and has always done it since. Honestly I never have to go wide open so never put any time into it since normal driving is fine. Roughly 20k miles since install, new plugs installed at time of engine install. No check engine light or codes, I put a set of a/m coils on last fall. Fuel filter has 5k miles since it was changed, I cleaned t-body last fall as well, rechecked last week and still clean, I cleaned the maf. Driver valve cover gasket was leaking recently so went ahead and put a new valve cover on it that has the built pcv inlet. Clean air filter, replaced fuel pump driver module last, had the dreaded hole from corrosion in it. Truck is all stock other than muffler, does have some kind of a/m flowmaster type muffler only. Assume it's stock tune. No vacuum leaks that I can find, fuel pressure on my scanner while driving is around 40 psi. I'm at a loss at this point, wondering if the fuel pump still could be the issue not supplying enough under load or if cats could do it. Debating removing the cat y pipe and taking for a quick drive to determine if any difference but wanted someone else to see if I overlooked anything. Thanks

 

Im facing the same type of problem. Hesitation/missing under heavy acceleration. Ive done the FPDM, TPS, and TB/MAF cleaning at this point. Going to be doing Coils and plugs next all OEM. After that I trying cats. If that doesn't get it then I'm doing the fuel pump.

Running without the cats will **** it off beyond recognition so thats not really a good way to see what it does and doesn't like.

 

I've done way more than both of you including injectors and I still swear this 04 is a dog at times. Hesitation, sometimes falls flat on its face, other times seems ok. Plugs, coils , filters, fuel module, cats, maf, timing job and on and on and on. Let me know if you solve yours

 

Couple questions. Why the need for WOT? I have always been reluctant to stomp on any of my vehicles as the wear and tear on drivetrain and engine has to be extreme when you are always stomping your foot into any vehicle. With that said I have an 04' F150 that has similar issues when I get hard on the accelerator, (rare by the way, ) I have never spent a lot of time and money on this as I just keep my foot out of the radiator, problem solved.

 

 

Just to clarify, I have had the plugs and cam phasers replaced on mine.. around 70,000 miles. 123000 miles now and it runs pretty good. My theory on the hesitation thing, the timing system on these engines is crap. There has to be slack in the chain when you get on it hard, and would that not cause some balking or stumbling? Your only fix may be to replace the timing gear. Mine makes the standard rattle noise on startup if it sets a day or so. Tells me the chain tensioners are leaking down. Once the oil pressure is up of course the chain is pretty snug. I tow about 7000 lbs all summer and have had some pretty hard rpms going up the hills, but no hesitating. The only time I really notice it is the quick down stomp on the foot feed. The act of quickly applying the throttle creates the chain slack? Postulating a theory.