Idle issues after warm up
#1
Newbie
Thread Starter
Join Date: Dec 2010
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Idle issues after warm up
So as the title says I am having issues with the idle on my 2000 sport, with the 4.0L.
It starts fine runs well and drives normal. But after the engine is warm and has been run for any distance, when I stop at say a light the idle drops really low. Then amps fall, and my oil pressure follows. (I am thinking due to the low rpm's) Though when I touch the gas everything snaps back to normal, and off we go.
It never stalls just drops to a few hundred rpm. Any ideas?
And I used the search, just didn't find anything that matched up. Thanks
It starts fine runs well and drives normal. But after the engine is warm and has been run for any distance, when I stop at say a light the idle drops really low. Then amps fall, and my oil pressure follows. (I am thinking due to the low rpm's) Though when I touch the gas everything snaps back to normal, and off we go.
It never stalls just drops to a few hundred rpm. Any ideas?
And I used the search, just didn't find anything that matched up. Thanks
#2
Seasoned Member
Join Date: Jul 2010
Location: Central Florida
Posts: 491
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
I would start by cleaning the throttle body. It is easy to remove. Pay close attention to the idle air control. Make sure the "plunger" and the housing are clean.
#3
CF Veteran
Join Date: Nov 2010
Location: In the middle of Minnesota!
Posts: 5,805
Received 99 Likes
on
88 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
The Idle Air Control (IAC) is mounted on the back of the throttle body. 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
Reinstall IAC and check idle quality
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
Reinstall IAC and check idle quality
Thread
Thread Starter
Forum
Replies
Last Post
jurazov
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
12
07-20-2023 04:13 AM
Jamesmon4
Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here!
1
08-16-2016 09:04 PM
Tcq192
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
7
10-23-2015 09:25 AM
WomanNeedsJeepExpertise
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
21
09-10-2015 06:01 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)