High idle on 4.0L

[tugboat94]

My 94 Ranger 4.0L is idling at 1300. I had a friend put a Snap-On scan tool and it said the TPS was out of range. I put a new TPS on and it is still the same 1300 rpm. I checked the IAC with a VOM and it checked out fine but when I pulled the plug off with the engine running there was no change in RPM. Any ideas out there?

 

[jasonl]

Did you check the throttle plate to make sure it doesn't have deposits keeping it from closing properly?

 

[tugboat94]

Yes I cleaned it all up. I took it off to clean back and front. There is a slight sticking issue when you open the throttle plate up. I don't see that as a problem though. I can't find any vacuum leaks. I am at a loss for ideas.

 

[jasonl]

If you unplug the IAC and it stays running then it's getting it's air from somewhere else. If the tps is saying out of range, it sure sounds like your throttle plate is not closed. Did you mess with the set screw on the throttle body? You can back probe the tps to see what it's reading. I believe it should be right around .96 volt

 

[tugboat94]

Thank you for your reply. I am back to work and won't be able to try anything until end of March. Yes like so many others I have backed off the screw to the throttle linkage. I will back probe the TPS and see whats going on there.