truck runs rough when it warms up

Asked by Mar 22, 2016 at 06:03 PM about the 2004 Ford F-150 XLT SuperCrew

Question type: Maintenance & Repair

i have a 2004 f150 with a 4.6 engine . the truck runs fine when i first start it but
once it warms up it start to sputter  when i give it the gas. the engine light is on
but not blinking. any suggestions?

9 Answers


IAC, dirty throttle body, bad spark plug(s), spark plug wires, etc. You have to begin a process of elimination. First, get the code read from a place like autozone. It would lead you into a direction.


Hate to break it to u but u have phaser issues. It's a system that is used to automatically adjust timing on each camshaft and they work with oil pressure. When cold the oil viscocity is good as it worms up, oil viscosity drops and oil pressure drops below 25psi and phasers can't do their thing. Check oil pressure with a pressure gauge

1 people found this helpful.

I have the same problem I have replaced phasers timing chain ( because it broke) also changed the oil,oil pump, and filter put new coil pack in and it's still running rough when it warms up

1 people found this helpful.

Check oil pressure, it probably drops after it gets warmed up. If pressure drops below 30psi, the phasers won't work because they work with oil pressure. If it's low, u have internal engine wear. Time for rebuilt engine


Oil pressure stays up and is fine I was told to change the oil every 500 miles until it clears out all the tiny metal shavings they were clogging up the small screens on the phasers does this make since


Well if the screens on phasers are clogged up, changing the oil is not gonna get rid of it. you would have to remove the phasers are rinse the screens to clean them but yes, if screens are dirty, it will cause it to miss cause they work with oil pressure. They're easy to remove. If you do, just make sure you secure the allen socket to the extension otherwise you can drop the tool inside and it'll be a nightmare to find it


By the way, not the phasers but the solenoid valves that activate the phasers. They're mounted one each end of the valve covers. 1ea.

1 people found this helpful.

Believe me, been there done that, after replacing all but 2 sensors, and then getting ready to replace the fuel pump. Accidentally bumped the kick panel where the computer is, found out I had one of the harnesses come loose from the computer, check all of your computer connections first, I believe

2 people found this helpful.

Im habing the same problem with 2006 5.4 liter. Replaced coils fuel pump plugs checked vacuum lines amd everthing you start by doing.. Still stalling when warm . does anyone know if this will throw a lean code if phasers are working property... Also i unplugged VCT selonoids and was told to try it for a day.. Still stalled amd ran like garabe.

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