cherokeeyed

1988 Jeep Cherokee XJ. 4 DOOR 4X4.

THis jeep has been nothing but a pain. When cold it will not idle unless I adjust the screw on the throttle body to hold the idle open. Once it warms up and I drive it to my next destination the idle will then hang abnormally high. I'll then remove the screw complete from the throttle body and it will then idle but it idles rough as can be and will sometimes stall. When I go to start it back up, it won't start unless I give it a healthy amount of gas and then it will just die. I have to hold my foot on the pedal a little bit to keep it running.

When I first bought it I put plugs, new air filter (it didn't have one) and a 195* thermostat in it. I've cleaned the throttle body and sensors on it.

Radi

Idle air control valve dirty or stuck?

Scotty16

Have you cleaned all the grounds? also, have you adjusted the TPS?

cherokeeyed

I'm not sure if its stuck but I pulled it and the tip was covered (black) so I cleaned it up and put it back in. How would a person verify if it was stuck?

cherokeeyed

I have not cleaned any of the grounds.

cherokeeyed

I finally just got the chance to do a little research on the TPS. Now that I know what it is and how it works, it will be my primary focus, I think. From what I read with an auto tranny the TPS has a connector for the ECM and TCM. Seeing that it has a connection to the transmission leads me to believe that, it is my problem because the Cherokee doesn't seem to be shifting right on its downshifts, say if I'm pulling a hill it doesn't kick down as easily as it should, I have to literally floor it for it to kick down.


Correct me if I'm wrong but am I headed in the right direction?

freegdr

Have you ever adjusted the detent cable ? It regulates valve body prrssure for up shifting and down shifting as for the tps checking it for proper voltages should be addressed.

freegdr

READ.....https://www.cherokeeforum.com/f2/ren...orrect-181192/

cruiser54

You're possibly on the wrong track. The two connectors on the TPS are not related at all, except for sharing a common ground point.......

The posts suggested below are in the pink link in my signature, with some photos.

First off, before doing any more monkeying around, clean your throttle body and IAC. Set the throttle body back to stock using post 11.

Courtesy of TJWalker:
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The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

“Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled







Then do the ground refreshing in post 1, followed by the C101 cleaning in post 2, followed by the connector refreshing in post 3, followed by the sensor ground test in post 5.

Adjust your TV cable to the trans as suggested.

https://www.cherokeeforum.com/f2/free-quick-fix-41821/

freegdr

Listen...^^^^

cherokeeyed

I'm about to head up to the shop now. I'm going to spend the rest of the day going through this thing with every tip you've left me with. Hopefully it cleans itself up.


Is there any major downfall to the renix over the 4.0 HO? Or is there anything better about the renix vs the 4.0 HO?

PDEM87

There's pros and cons with both systems. Some guys get better mileage with the renix. The biggest thing is just getting to know how things work and how to maintain operation. As with anything with adjustment, there is opertunity to improve or screw up performance.

cruiser54

Excellent plan. Look forward to hearing back.

cherokeeyed

I didn't get fixed what I had planned to get fixed due to the amount of snow we received, I had to use the Jeep to get around. I did however try to clean the ground reference point on the oil dip stick to find that all the ground wire eyelets were stuck together so good that I could not get them apart, no matter what I tried. I soaked them in PB blaster as well as brake clean.


Tomorrow, Ill be getting back to my TPS, Idling problem I'm having.

cherokeeyed

This morning I figured I would start with your list from top to bottom. Like I previously state my grounds at the main ground source were all stuck together, I will re-address them once I can get back up to my dads shop. I moved on to the c101 connector, pulled it and it was a mess. I cleaned it to the best of my ability with break clean and some small picks, plugged it back in and tightened down the bolt. Fired the jeep up, I did have to give it a little gas, given its about 30* where I live that didn't bother me much, I didn't have to hold down the pedal but for maybe a minute before it would idle on its own and idle rather smooth. I think once I get the butterfly adjustment bolt back in the throttle body and adjusted correctly the Jeep will be idling fine.


I've read up on how to adjust the butterfly on a post from cruiser, what I took from it is, adjust the screw until you see the slightest bit of movement in the butterfly. Correct me, if I'm wrong?