Mechanics

F150 TRUCK HAS A ROUGH IDLE AND ACTS LIKE IT IS M

1990 Ford F-150

1990 Ford F150 V8 Four Wheel Drive Automatic 175432 miles

I changed the plug and wires cap and roter. Cleaned the egr valve amd it still has the problem of like it is missing. I have checked for any kind of vacume leaks and found none. Replaced the cat on it and put a new exaust on the pick up at between 35 to 45 mph it has a really bad shimy in the moter but at a high rate of speed it dont have a problem with running at all
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William CODT BARRETT
March 11, 2009.



Ok I would check the TPS (throttle possition sensor). With a digital multi meter back probe the green wire at the tps with a paper clip and hook the poss of the meter to the paper clip and the neg of the meter to the neg of batt. Now with key on engine off the tps should show about.8 ot 1 volt and then slowly lift the throttle and the voltage should slowly and steadly increase to about 4.5 to 5 volt. If there is any drops or glitches in the voltage then replace the tps. If that tests good then test he IAC motor.

Racefan966
Mar 12, 2009.


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