My 95 bronco 351w is idleing to fast, about 1200 rpm. I can kick the throttle and make it come down but all i'm doing is making the butterfly valves in the throttle body jam shut. There is still vacuum in the throttle body trying to open the butterfly vavles. So when I step on the gas and let off normally, the vacuum holds the butterfly vavles open just enough to make it idle high. When I disconect the idle air control vavle it idle's fine, about 700 rpm. I've replaced the idle air control vavle, this is what creats the vacuum in the throttle body, and senser twice. So I know they are ok. So for some reason the cpu is telling the idle air control vavle to creat to much vacuum in the throttle body. Weird thing is when I start it, it idles high for 20 seconds then idle's down on it's own to where it should be. Vary little vacuum in the throttle body. But as soon as I step on the gas padel, the vacuum goes up and stays there. It's kinda hard to hold her back at stop light's, keeps wanting to climb up onto the car in front of me. Hay that would be kinda fun. Well, any suggestions would be helpfull! Thanks. Ed_Edde_&_Eddie_Bauer

 

I had/havethe same problem. I replaced the TP sensor and it ran fine for about 2 months, now it's back to doin it iradically. If you find out what it is would ya let me know.

 

Try cleaning the throttle body with a spray cleaner, maybe some carbon build up causing the butterflies to stay open a bit. Also check and see if the return springs are binding somewhere. Hope this will help.

Warr

 

just dont use carb cleaner. you need to use cleaner that is special for throttlebody.

 

Thanks guys. The throttle body is clean, it's the vacuum sucking it open. I'm going to try changing the throttle posistioning sensor to see if that helps.

 

Check this thread:
https://www.ford-trucks.com/forums/s...d.php?t=212832

It's unlikely that there's vacuum pulling the throttle body open. Check out the TPS voltage at idle, and make sure that the throttle body goes back to the same position every time it closes. If it doesn't, clean it up some more, or add another return spring.

 

I had the same problem with my 95EB. I replaced the TP sensor and the IAC as well as cleaned the butterfly...eventually had to have the entire throttle body replaced...now it runs great.
woody

 

yup if all else fails, it could be that it has enough wear thats it pull air (vacuun) around the throtle shaft on the top and bottom, if so you'll have to eventualy replace the throtle body DW