Summary
The problem might not be there. Carbon deposits in the EGR passages may be loose and only hold the EGR valve open at times. You can try testing the EGR operation by manually moving the valve up and down several times while monitoring the voltage feedback from it. The voltage should always return to the same reading, indicating the valve movement is consistent. If the voltage readings vary when the valve is released, it is likely due to carbon deposits on the valve seat.
If the valve remains open too far when it is supposed to be closed, it will set a code in the engine computer. You can try removing the valve and cleaning the valve seat but the Ford recommends replacement. Also check engine passages for loose carbon bits. I have seen small round pellets form in the passages that intermittently hold the valve open. If you don't blow these out of the passages, a new valve may still act the same way.See the full content of this document
Extract
Tuneups and Sensor Checksfail to Fix F150
Jim Kerr / Backyard Mechanic
Question -- My 2002 F150, after warming up, starts missing. It is worse at lower speeds and seems to clear at high speeds. I've had it to a mechanic and the following was done: code che...See the full content of this document
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