Hi Everyone,
I need help with my F250 1991 (came off the line in 1990). The engine races and will not idle down. It is like driving my tractor- just put it in gear and go- don't have to use the gas pedal. I have already replaced the Engine Idle Control Valve and was told the next thing to try is the Throttle Position Sensor. Where the heck is it? I picked up a new sensor but can't seem to find anything that looks like it on the truck. Don't go makin' fun of me--- how many other 63 year old females do you know who would even be doing all this stuff? Any help would be appreciated. It is getting into hay season and I need my farm truck to be running well.
Thanks.
Ali

 

Welcome to FTE!!

What engine? 300, 302, 351?

If it's the 300, its located on the side of the TB(Throttle Body) if it's the 302 or 351, its located on the bottom of the TB.

Also, have you checked for trouble codes?

 

The Engine Idle Control Valve is on the side of the Throttle Body. I don't see the Throttle Position Sensor being there also- at least it does not look like the pictures I've seen or the replacement I brought home.

 

What engine?

 

Could be a bad coolant temp sensor, or bad wiring related to that. If the computer thinks the engine is "cold", it'll speed the idle up quite high, especially if the CTS is in failure mode.

 

Wait a sec... lets see where this high idle is coming from first.

Unplug the idle air control valve.
If idle returns to normal, then you know the computer is commanding a high idle for some reason, and we go from there.

If idle stays high after unplugging the idle air valve, then it's NOT a sensor or computer issue. Disconnect the throttle (and cruise if the truck has it) cable, and try again. If it's still idling high, try to push the throttle all the way closed, it could just be sticking. And if it still idles high after that, you probably have a vacuum leak.

 

OK, I have replaced the idle air control valve (a friend suggested this first and the old one was original and gunked up when I took it out) but that did not solve the problem. The next thing I was going to try was replacing the throttle position sensor. I finally found it on the bottom of the throttle body. Will try to get at it and replace this weekend. I have played with the throttle and it does not appear to be sticking. Have also replaced some of the vacume lines. Still the same racing. So, like I said throttle position sensor next then I guess the coolant temp sensor and/or its wiring- unless someone else has another idea that sounds better. Thanks for all your help guys.

 

Post#6: Ford Truck Enthusiasts Forums - View Single Post - F250 "racing" engine

 

x2^^

Always diagnose problems, don't just throw parts at it. Saves lot's of $$ and time