luke0302

I have a 2004 f150 with the 5.4 and i am having a problem with the idle when the engine is warm at a stop light or sign it idles down to 500 then a quick jump back to 700 then back down to 500. Every now and then it wont start it will crank but not turn over until you stop for about 2 seconds then it will turn over and run fine. No engine code at all. Changed tps, cleaned throttle body, and had the gas lines flushed the other day but still having the idle issue and tired of throwing parts at it. was wondering if anybody has had simular problem the might lead me in the right direction.

threef150ees

i would say idler air control valve or vacuum leak somewhere...

melrose99

Look at your fuel pump drive modular, above your spare tire. Might be corroded.

luke0302

Thanks for the replies but my yr of truck does not have an aic its all electronic. I checked the fuel pump modular and i guess you were talking about the electrical plug to check for corrosion and there was none. How do i go about checking for vacuum leak myself or do i have to take it in? Any other ideas are greatly appreciated its got me stumped.

Nalb1221

Clean the mass airflow sensor. Also there has been an update for the PCM that adjust the idle and whatnot. You would need to go to a ford dealer and have them reflash the PCM with the update. I haven't done it yet but I have an edge evo tuner and I adjust my idle with that. These trucks idle low 500rpms is just to low, as for the idle jumping I would clean the M.A.S. Start cheap you already did the throttle body. Also check for vacuum leaks oh and just for the hell of it check the seal on the air box tray it could be sucking unfiltered air, it's in the bog down/ moan solved thread.

luke0302

cleaned maf raised my idle up with my evo and changed seal on airbox. Still having the same problem just idles up to a higher rpm then back down.

Especial86

iTrader: (1)

Try the diamondbird trick. If that doesn't work then the throttle body itself may need to be replaced due to an issue with the servo.