Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here XJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.

Rpm dropping whenever I brake

Thread Tools
 
Search this Thread
 
Old Jul 25, 2024 | 09:26 AM
  #1  
ajfran3's Avatar
Thread Starter
Member
Liked
 
Joined: Jan 2024
Posts: 156
Likes: 29
From: Greensboro
Year: 1995
Model: Cherokee (XJ)
Engine: 4.0
Default Rpm dropping whenever I let off gas

Hello I'm having an issue where Im driving and I let off gas my rpms get lower then normal then go back up to normal idle rpm. When it is in park and idleing at what is shown in the second picture I gave it some gas and let off the rpms dropped to about what is shown in first picture and then after about 15 or 30 seconds it goes back too the rpms shown in image 2. When driving it drives fine and sounds fine it just a little worrying when it gets that low in rpm for a second. Any thoughts. I just tried changing the TPS and that didn't do much for it



Last edited by ajfran3; Jul 25, 2024 at 03:46 PM. Reason: New information about whats going on
Reply
Old Jul 25, 2024 | 12:44 PM
  #2  
BadBloodXJ's Avatar
Member
Liked
Loved
Community Favorite
 
Joined: Jul 2024
Posts: 165
Likes: 75
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0L
Default

Not exactly sure, I would start with the Idle Air Control Valve.
Reply
Old Jul 25, 2024 | 02:46 PM
  #3  
tjwalker's Avatar
CF Veteran
15 Year Member
Liked
Loved
Community Favorite
 
Joined: Nov 2010
Posts: 5,841
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
Default

A leak in the "brake booster" and or lines associated with it.
Reply
Old Jul 25, 2024 | 02:48 PM
  #4  
ajfran3's Avatar
Thread Starter
Member
Liked
 
Joined: Jan 2024
Posts: 156
Likes: 29
From: Greensboro
Year: 1995
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by tjwalker
A leak in the "brake booster" and or lines associated with it.
I just made an edit the brakes are operating fine and it doesn't matter if I push breaks. It happens as soon as I let off the gas. I tried revved it in park and let off gas and it went down to below normal idle and then went back up to normal idle after about 15 to 30 seconds
Reply
Old Jul 25, 2024 | 03:51 PM
  #5  
ajfran3's Avatar
Thread Starter
Member
Liked
 
Joined: Jan 2024
Posts: 156
Likes: 29
From: Greensboro
Year: 1995
Model: Cherokee (XJ)
Engine: 4.0
Default

Alright so after doing some more testing with AC on and ac off the rpm droppage only happens when the AC is on. Standing watching the compressor when I move the throttle to give it some gas and let go the rpms drop and the AC clutch stops every time. If I do it with AC off the rpms drop back to normal Everytime. Does that mean the compressor is bad, I just got this compressor as a warranty replacement from rock auto because the last one was leaking. I installed myself and had it recharged and it was fine yesterday I made sure to spin the clutch around about 15 rotations like it said to oil the seals and it was spinning fine. I didnt have this problem but today I am. The compressor is a uac compressor
Reply
Old Jul 25, 2024 | 04:49 PM
  #6  
RockyMtn96XJ's Avatar
CF Veteran
5 Year Member
Liked
Loved
Community Favorite
 
Joined: Aug 2019
Posts: 1,487
Likes: 273
From: Littleton, CO
Year: '96
Model: Cherokee (XJ)
Engine: 4.0 HO
Default

I wonder if the clutch being engaged is adding friction that it shouldn't be, making it a little more difficult for the motor to turn. With the motor off, take the belt off and actuate the AC clutch manually with a 12volt source and try to turn the pulley then...??? I dont know how much resistance there should be, but if its really hard to turn, then that MIGHT be an issue. It might be impossible to turn if you try this with a fully recharged AC due to the system pressure. Maybe you can turn it with a wrench.

Maybe something inside the compressor isnt right.

These are just ideas I pulled from my.... brain. I havent dealt with this issue before...

Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Dave51
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
2
Aug 11, 2023 05:09 PM
Spartan13Friday
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
1
Apr 19, 2017 10:30 PM
jmlo96
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
2
Aug 21, 2013 05:27 PM
MickDime
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
2
Feb 6, 2011 09:41 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 



All times are GMT -5. The time now is 01:58 PM.