stupid idle probs!!

[superfiveo]

It's 50 degrees out why does this thing want to idle at 1500 for an half hour?!?!?!

 

[Bounty__Hunter]

What thing? Being a little more specific would help us help you.

 

[superfiveo]

oops :roll: sorry about that, It's a 89 Cherokee 4.0L 5 speed.

When I first start it It idles around 800 for about 2 minutes then it gradually goes up to 1500 and stays for 15 to 20 minutes. What should I test first?

 

[Bounty__Hunter]

Remove the throttle body and all it's sensors. Clean the throttle body and sensor housings real good with carb cleaner and a tooth brush.

Is this engine TBI or MPFI?

 

[superfiveo]

It is MPFI. Does any body make a good book on this FI system? I bought a Haynes manual and it only covers the newer computers with self diognostics tests. Thanks

 

[XJNick]

Definately clean the Throttle body and the Idle Air Control Motor (IAC) passageways. If it still idles high, suspect a faulty Coolant temp. sender (CTS) or Mass Air temp. sensor (MAT). :mrgreen:

-Nick :!:

 

[superfiveo]

2001 TJ Saraha $15K

Ok I cleaned every thing and it is still doing it. How do I check tha CTS & MAT. Also When its doing it's high idle, it sounds like shit, sounds like an old tracktor. but it's not missing. Thanks

 

[sparkyshotrods25]

because it more than likely is computer controlled and the comp is trying to make up for it by adjusting the Idel possition sensor as a reasult .If you also have to degree the distributer that much your timing chain is screwed.I am not sure but i think that some of those they used plastic gears so i would definatley check the timing chain out.one other possibility could be the O2 sensor.You didnt say how it was when it did this but that can affect it too,trying to warm the engine up.hope this helped