Fast/high idle

[acidrainburn]

I looked but didn't see anything like this described.. I have a 91 explorer with the 4 Liter, when it starts it idles normal, after a few seconds running time the idle creeps up to 1500-2500 rpm.

I've replaced the throttle air by pass valve, to no avail.. What are my options, and where do I find the fix?

Thanks to you all that replied, with a can of carb cleaner, www.autozone.com libraries I cleaned the throttle plate and "rebuilt" the throttle sensor, it's now idling smoothly at 800 rpm. with no hasitation, or mis fires.. again THANK YOU!

 

[SteveVB]

TPS

Pull the codes I would bet its the TPS going bad- $30 and 5 min to install.

 

[Robert]

On my '97 a high idle problem was fixed by replacing my thermostat that stuck closed. The high idle problem didn't start until a few minutes after starting out (once the engine warms up). My computer bumped my idle up a bit to try and keep the engine cooler. If that was a feature back in '91, I would give it a look. Does your temperature gauge read any higher than normal?

 

[Big E]

Try a can of carb and choke cleaner down the throttle plate. Might be all carboned up. you can use a tooth brush to ade in the cleaning of the throttle plate.

Eric