crazycooter

Hello I have a 04 FX4 with a 5.4L. It has developed a intermittent problem where when floored full throttle it will jump between 2500 and 3000rpm. It will not go over 3000rpm. It also sometimes stalls. It seems to happen more when it has been warmed up.
No codes!
I have suspected the fuel pump or a coil but I am not sure. It has 47000 miles on it.
Any help please!!

rtg143

Has the fuel filter been replaced lately?

crazycooter

Sorry, forgot to ad that I installed new fuel filter and that did not help.

FORDNATIC

Have simillar problem with an 05 5.4. It will drive fine but when kickin it down wont rev above 4000. Dealer said caliper hung up,then #5 injecter bad,then convertors plugged still there. Called ford tech support and they said bad plug,coil on #5. Replaced no help. Now they say to replace all plugs and coils. We had also replaced fuel filter.Wow talk about throwin parts at it. Am not sure but leanin towards fuel pump or maf. Also wonderin if throttle has something to do with it. Tranny shifts fine just happens when wide open throttle trying to pass. Lost and will have a million dollar city driver if cant figure out.

FX4_Envy

I'd get my hands on a fuel pressure gauge and give it a check.

sidecar bob

Having the same issue on 07 f150 harley saleen revs ups to about 3500 or so and boost gauge shows bout 10 lbs of boost then starts to slowly fall off till it barely idles. shut the truck off and restart idles ok but wont develop any power. tried new fuel filter and a new pump , no luck thinking it may be in the exhaust waiting for the dealer to open tomorrow did find a tsb on Harley supercharged catalytic converter noises being replaced so I am hoping, may be worth looking into on yours too . but I am am looking for other ideas too no steady codes are being thrown got a couple for the cats and one misfire on 5 also but the have not came back after I cleared them.

jazar10

could be bad plugs, had like 7 plugs go on my truck, and barely work, and my truck couldn't hit 40. u might have 1 or 2 bad ones

sidecar bob

wouldnt that throw misfire codes if it was the plugs or coil pack?

jazar10

mine didnt throw codes surprisingly. only a p0420 code. but thats for the cat

FORDNATIC

All plugs and coils changed. Still not right. Did find out through some contacts that 05's have a problem with main connector to computer. Some pins fit loose causing a runability problem with no codes or strange codes. Fix suposedly is to unplug put dielectric grease on and reconnect. Have not tried this yet but will check out.