1992 F-150 5.8l 351W Rough idle wont go away plz help!!!!!!!!!!!

[FORD35192]

i have changed the Map sensor, TPS sensor and set it to 0.99V as stated in my book, Fuel vapor purge valve, Idle position sensor, EGR valve, EGR solinoid, PCV valve, O2 sensor. i also checked for vaccum leaks over and over again, and cleaned the throttle body with "seafoam". I also bought a code scanner and it only pulls a system pass code (111). I can not figure out what causes the rough, and high idle problems. The truck idles at about 1500 rpm but is very rough, however when your actually driving it runs perfect with no hesitation or lack of power. Any comments you think might help would be appericated.

[corning_d3]

The only things i can think of off hand are the plugs, wires, dirty injectors, MAP sensor or PCV Valve..

[unclebubbles]

Originally Posted by FORD35192

i have changed the Map sensor, TPS sensor and set it to 0.99V as stated in my book, Fuel vapor purge valve, Idle position sensor, EGR valve, EGR solinoid, PCV valve, O2 sensor. i also checked for vaccum leaks over and over again, and cleaned the throttle body with "seafoam". I also bought a code scanner and it only pulls a system pass code (111). I can not figure out what causes the rough, and high idle problems. The truck idles at about 1500 rpm but is very rough, however when your actually driving it runs perfect with no hesitation or lack of power. Any comments you think might help would be appericated.

If you disconnected the battery while changing components, any stored trouble codes would be cleared. But just for grins, you could use the self test connector, and the MIL to see if it gives you the same results as the scan tool. After you do this, disconnect the battery for 5 or 10 minutes, to clear the KAM. This will allow the processor to relearn the correction factors for the new components. Then you will have to drive it a few miles, and go through a few start/ stop cycles, for the computer to reset. Some vehicles clear up right away, some take a few miles. If this doesnt help , do some more vacumn leak tests. Take a can of carb cleaner, or wd 40 or similar, and spray at the manifold gaskets. If you have a leak, the spray will be drawn in, and it should smooth out somewhat. Good luck
Later
Ed
.

[truckdude239]

i have an 87 ford f-150 with the same problem turns out i had an burned vavle not reall bad but enough to make it idle rough

[corning_d3]

Yeah, i forgot to mention burnt exhaust valves are sorta common on these engines.

[transgta]

my 01 f150 idles rough enough you can feel the floor shake at times but runs perf also. Went to ford they told me thats just ford i was pissed. If i rev it about 1500 rpm is the worst miss of all but floor it driving doesnt miss at all

[carrb24]

sounds like a manifold vacuum leak, have you changed the valve cover gaskets?