ive been having this problem for a while now. my truck used to only idle at 3500 when it was cold, but lately its been doing it even when warmed up. sometimes it doesnt stop until ive been driving around for 15-20 minutes. its almost dangerous. i have replaced the tps, fpr, iac, cap, rotor, wires, plugs, coil, and i cant find any vacuum leaks. i have cleaned the throttle body numerous times and the cable isnt sticking. sometimes if i blip the throttle it will go away for a minute or two but then come back. i dont know what else it could be. truck is in sig.

 

Have you pulled codes? Why throw parts at it break out he multimeter and test that all those things are within spec.

 

is the throttle sticking open , have you unhooked the linkage to see if some thing is getting stuck ?

 

nothing seems to be getting stuck in the linkage, ive checked that many times. im getting codes 179, 327 and 328.

 

My truck idle sticks also.The guy I brought it from said that was normal
(bull----).
I replaced ever thing under the hood.
I think mine is the computer. What I been doing for almost 3 years is each time I start it(cold and hot) I tap the gas pedal right when the motor starts. It works about 95% of the time. If it is still idle high I shut it down and redo above step.

 

okay thanks, il give that a try tomorow morning.

 

could this be a map sensor issue? my mpg's are far from excellent.

 

Generally no excapt that it is attached to the vacuum system, but the line is pretty small so I doubt that is your problem. What happens if you start the motor and get it idling(screaming) at 3500rpm and unplug the IAC or TPS individually.. meaning not at the same time? Does this have any effect on the idle speed? Have you tried disconnecting and plugging the vacuum line to the brake booster?

 

Try unhooking the IAC while its running cold or warm? What happens? pull the vacuum line of the MAP and see what that does. put a vacuum pump on the MAP try 10hg and then 20hg see if there is any change

 

okay thanks, im gonna try those ideas right now....where is the map sensor?

 

Try unplugging the idle air control, if it idles normal you have a vacuum leak somewhere, mine has the same problem and after replacing all the vacuum lines I found my intake is leaking, you can find out where its coming from by spraying ether in spots, the idle will drop

 

I am having the same problem. What is going on? I have had several 302's and never had this problem.

 

i had the same isssue, but i can't tell you what my RPMs were since i don't have a tach. anyway, after tearing it down to the intake and having my friend with a ton more experience and know how dig deep and search, the thing we finally stumbled upon was the new TPS (2 wks old!!!) was not reading right on the multimeter. now with the new one in, i haven't had the idle surge problem. just gotta clear the codes that were stored to make sure it's running properly. all that to say this, try checking your voltage on the TPS.

 

Good to know thanks!

 

i did my codes today and got 122 and 327.
122- throttle position sensor below minimum voltage
327 - evp/ept circuit below minimum voltage
i cleared the codes and kept getting these a few days in a row. im assuming my tps is bad, and i guess my egr valve sensor is also bad? rockauto refers to it as the egr pressure feedback sensor.