Help

Ok i have a 1988 cherokee laredo with the 4.0-Auto and i am haveing a problem with the idle usually when it starts it idles fine but after i take it for a drive and then come to a park it idles really high usuall about 1500 to 2000 and wont idle back down below 1000 unless im in gear and on the brakes. I have checked the map an it was fine i also cleaned the IAC valve witch did help with idle at startup it no longer revs to 2grand so now im stuck and am thinking it might be ther CTS but im not sure any advice?

you probably have a bad throtle position sensor. do you have any way of checking the setting. it should be set to 12-14%. my guess is that it is set higher.

jneary said:

you probably have a bad throtle position sensor. do you have any way of checking the setting. it should be set to 12-14%. my guess is that it is set higher.

Click to expand...

How do i check it i do have a dvom.

i learned how to do that years ago in a class, but have since forgot due to having access to the factory scan tool at work. check for other posts and you will find good methods or possibly borrow a scan tool from an auto parts store, or if all else fails, take it to the dealer.

jneary said:

i learned how to do that years ago in a class, but have since forgot due to having access to the factory scan tool at work. check for other posts and you will find good methods or possibly borrow a scan tool from an auto parts store, or if all else fails, take it to the dealer.

Click to expand...

Get your mitts on a factory service manual for your year XJ. It tells how to check that.

I had a similar prob.

The test for the tps goes: Using a migh-impedence dvom, connect the pos. probe to the center terminal and the neg probe to the black (grnd). With ign on slowly move the throttle lever until it is wide open and observe the reading on the meter. Closed throttle should read greater than 200mv. Throttle open should be a little less than 4.8volts.

The color coding and positioning was a little different on mine but I found the combo that gave me the right results. My tps tested ok. Cleaning the battery terminals solved it for me.

Good luck and good wheeling.
Cherokid

Little bits of grit get caught in the AIS motor gears and cause it to stick sometimes. Check tps, if that doesn't fix problem take ais motor off and clean it. Leave it plugged in and turn the key on. It should move some, kinda like a self test. Its basically a worm drive solenoid. We replace them at work once in a while because they stick and the idle wont come down.

OregonXJ said:

Ok i have a 1988 cherokee laredo with the 4.0-Auto and i am haveing a problem with the idle usually when it starts it idles fine but after i take it for a drive and then come to a park it idles really high usuall about 1500 to 2000 and wont idle back down below 1000 unless im in gear and on the brakes. I have checked the map an it was fine i also cleaned the IAC valve witch did help with idle at startup it no longer revs to 2grand so now im stuck and am thinking it might be ther CTS but im not sure any advice?

Click to expand...