Idling fast when hot!

[monkeydude3]

Hello all~
I've posted and posted and searched and searched and I have come up empty handed. My 1994 XL 4.0L OHV 5 speed manual idles fine until it gets hot, and then it idles too fast! 900 rpm fast, when normally it idles at 700 rpm. Has anyone experienced this.... let me know if you have and anything that can fix it. Could I need a sea-foaming because there is so much carbon it needs to idle fast when hot??? I have no idea, I've checked as much as possible!!! Thanks!

George

 

[mrboyle]

I read your other post and can tell you its not the voltage regulator. There are no moving parts (like in a relay) inside the regulator. Are you sure it makes the "clicking" sound everytime before the idle jumps? My first guess would be a problem with the idle air controll motor, but without the vehicle its very difficult to diagnose the problem.

 

[monkeydude3]

that is new as well. What's mind boggling is how it runs great when warmING up, but once it's hot it just idles fast. I un plug the IAC and nothing happens. All the techs I know say if the IAC is being told to run fast when you disconnect it, it will drop down in idle. But that doesn't happen. It's just very confusing. Sorry

George

 

[TPLYNCH]

When you say it is running hot, how hot?? The computer will automatically bump up your idle if it is reading an overheating situation. If the engine is indeed running Hot, then that is why. If your temp gauge is reading normal, then the temp sensor that feeds the computer may be bad. There are 2 different sensors, one for the guage and one for the computer....

 

[monkeydude3]

The temp is reading on the cool side of normal.... which is what it has always read. By hot, I meaned fully warmed up. I opologize. This is just a problem which makes me wanna pull my hair out!!! I know it is going to be something stupid

 

[TPLYNCH]

I'd still check the temp sensor....

 

[monkeydude3]

Okay great... I've been leaning more towards that one. The temp sensor that feads the computer is the one I presume you are referring to. And that would be the one that has several wires coming out of it, correct? I have a feeling if I replace this sensor my woes will go away. Thanks!

George