Ideling to high

I have an '89 Jeep Cherokee and it idels way to high. In park it idels at from 1500-3000 after being warmed up. In drive it idels at 1300-1500. It idels at 2000 at 35 mph. We’ve replaced the O2 censor, the throttle postioning censor, the coolent temprature sensor, and a few other parts. None of this worked. Any ideas?

All the parts I replaced were from a junk yard so there is no garintee they work. Just putting that out there

You might want to tell folks what engine you have.

Is your check engine light on? Error codes?

Check out your idle air control valve (I think both the 4 & 6cyl engines had them), clean your throttle body, and make sure nothing is sticking on the throttle return.

its a 4.0. check engine light is not on.

[b] It idels at 2000 at 35 mph.[/b]  

 I'm sorry, but that just does not seem to make sense to me. Your car runs 35 mph at idle?

that was a mistake… at 35 mph it runs at 2000 rpm’s

In what gear?

its not just @35 mph that it runs high. the faster I go the higher the rpm’s. that was just an example.

Yes - the faster you go the higher the rpms - until the transmission shifts (or is shifted).

Are you saying that if it is in second gear and you don’t have your foot on the gas it will run at 2K rpms? (There is no “idle” if you’re moving and in 2nd gear).

Either way, it is still idling too high if it runs at 1500-3000 while in park.

One thing I’ve seen cause high idle ( not idel ) with a properly working idle control valve, is the wear on the butterfly in the throttle body.
Few think to look down it’s throat, but a car in our shop had worn a crescent space from the tension of the return spring holding the butterfly over to one side all the time.

This extra space, miniscule as it was, allowed sufficient extra airflow resulting in high idle.

They don’t sell the butterfly disc but only a throttle body assembly so we manufactured our own from a piece of steel.

ok so we fixed the idle problum on my jeep; turns out to be bad gaskets on the intake manifold. it were so bad it sucked air in thrugh the cracks and creating bad air/fuel mix in resalt of high idle… so check your gaskets

If this vehicle has an idle control valve…then it could reside there, but i woud start looking for vacume leaks first. You can look for and even listen for vacume leaks. A spray of wd40 is sometimes helpful for pesky leaks…you spray the hoses and if it is leaking…it will suck in the wd40 and lower the idle or make the engine stumble…then you found it. If it has an idle control valve then that assy is basically a controlled vacume leak…more leak more idle speed…less leak…less idle speed. If you have a vac leak outside of the idle valve then you will get very high idle conditions regardless of valve operation… Look for vac leaks…then go to the idle control…

Also if you have a valve for idle…it is most likely thermostatically controlled via engine coolant…if you dont have proper coolant level OR an air bubble in the system them the sensor will not be immersed in hot or cold coolant…check that for sure if it is thermo controlled.

H B - the solution was posted yesterday (above - leaking intake manifold).

LOL…Ya…Im movin slow today… Hey at least I was right tho…LOL

you were abslutly right actully… that is how my mechanic found the leak buy using carb cleaner. Its like putting a bike tube in a bucket of water, you will find the leak. thank your for your help I replaced all kinds of things to fix this issue so for now every thing is running properly