Engine feels like there's a slight miss. on 2005 Ford F-150

At idle and when holding a constant speed a slight roughness is noticed. Seems to go away when accelerating. Nothing seen via the tach in regards to large variations in RPM. Plugs and wires were replaced about 4,000 miles ago. Could it be EGR valve related?

by in Flower Mound, TX on August 24, 2013
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3 answers
ANSWER by , August 24, 2013
Sounds like you may have a arcing coil, i am assuming you have coil over plugs, the best way to find which one it is, is to start the engine and listen for a ticking sound under the hood, and look for spark arcing from coil to head, if you do not see it, start on one side or the other and unplug each coil one at a time, when you find the one that does not make a difference in the sound or vibration of the engine, replace that coil.I hope this helps, let me know you can email me at watsonautoservice@gmail.com or call me at 478-297-4710
ANSWER by , August 24, 2013
Very possible it is the EGR system! Big difference between slight roughness and an ignition misfire!!! A misfire will make the truck jerk and is more pronounced when torque converter is in lock up mode going up a slight incline, is this what you feel? Any good mechanic with a real scanner is what you need!
ANSWER by , August 24, 2013
take it to a dealer. they can do a power balance test drive to see which coil is dropping out. they should be able to look at mode 6 info to see which one has been missing.