For some time now my truck idles really rough. And sometimes to the pint of killing the engine. Today i took the throttle body off thinking there might have been a rather large amount of carbon build up inside. It was pretty bad so i cleaned it up really good. Put it all back together and its does idle a little smoother but it'll still kill the motor. Talked to 30yr mechanic and he advised there is type of butterfly inside the upper intake and that the seals have probably gone bad and its allowing a vacuum. Was wanting to know if there's any truth to that? Was planning on removing the upper intake manifold and getting a gasket kit and replace them all. Do you think this would or might fix my issue?

Thanks in advance for your feedback!

2004 F-150 XLT 2X4
5.4L 3V
137,650 miles

 

What he's talking about is the CMCV. It may or may not fix it, it would be best to drive around with a scanner that can display live data to help with the issue. If you had a vacuum leak, it would probably give you a CEL and lean codes.

 

I am already having the lean codes. P2195 AFR/02 Sensor Excess Lean Signal. P0171 and P0174 Side 1 bank 1 and side 2 bank 2. And also getting a P2072 code "Throttle Actuator Control System".

 

The throttle actuator control system could be the throttle body motor or the controller on the pedal itself.

Should have posted the codes in your first post.

Lean codes are probably a big vacuum leak somewhere, yep.

 

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