Notices
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.
Sponsored by:
Sponsored by:

Low rough idle at start.and low oil pressure once at operating temp

Old 05-11-2019, 06:53 PM
  #1  
Newbie
Thread Starter
 
Join Date: May 2019
Posts: 10
Model: Cherokee (XJ)
Default Low rough idle at start.and low oil pressure once at operating temp

I have a 1998 jeep chrokee classic and it has a harm time starting most the time you have to hold the gas to get it to start and also for it to run and after a couple seconds you can let off and it will idle ok for a few mins then I give it gas and once the rpms start going back down it acts like it wants to die...not to sure where to start I've been watching videos and searching forums and everyone seems to say something different.and also at start up i have around 40psi oil pressure and once it gets up to operating temp it drops down to about 10psi until you hit the throttle...if anyone could lend some advice I'd gladly appreciate it
Anthonyfid is offline  
Old 05-11-2019, 07:05 PM
  #2  
Senior Member
 
TrailerTrash's Avatar
 
Join Date: Jun 2017
Location: Hangover, PA
Posts: 501
Year: 1998
Model: Cherokee(XJ)
Engine: 4.0L
Default

Has it had a tune up any time recently? Could be a few things related to ignition parts.

Could also be the idle air control valve. Pretty sure that's what its called. Mine was bad and I had those exact starting, idling, and running symptoms
TrailerTrash is offline  
Old 05-11-2019, 07:14 PM
  #3  
Newbie
Thread Starter
 
Join Date: May 2019
Posts: 10
Model: Cherokee (XJ)
Default

Not that I know of

Last edited by Anthonyfid; 05-11-2019 at 08:32 PM.
Anthonyfid is offline  
Old 05-11-2019, 08:32 PM
  #4  
Newbie
Thread Starter
 
Join Date: May 2019
Posts: 10
Model: Cherokee (XJ)
Default

Originally Posted by TrailerTrash View Post
Has it had a tune up any time recently? Could be a few things related to ignition parts.

Could also be the idle air control valve. Pretty sure that's what its called. Mine was bad and I had those exact starting, idling, and running symptoms
Not that I know of I just bought it and the person didnt specify....but i have noticed I have some cracked vacuum lines...not to sure if that may contribute to the problem..I'd assume

Anthonyfid is offline  
Old 05-11-2019, 11:10 PM
  #5  
CF Veteran
 
jordan96xj's Avatar
 
Join Date: Dec 2015
Location: Syracuse, NY
Posts: 1,877
Year: 1996
Model: Cherokee (XJ)
Engine: 4.0L
Default

If a vehicle that starts ok, runs for a couple of minutes ok, but then suddenly starts degrading (stalling, stumbling, hesitating) these are the hallmarks of a failing/failed upstream O2 sensor. The computer does not use the sensor for the first minute or two during a cold start. But once the computer starts relying on it (after operating temperature gets high enough) the fuel trim calculations will start to get progressively worse (because the O2 sensor is feeding bad information to the computer).
jordan96xj is offline  
Old 05-11-2019, 11:45 PM
  #6  
Newbie
Thread Starter
 
Join Date: May 2019
Posts: 10
Model: Cherokee (XJ)
Default

Originally Posted by Anthonyfid View Post
Not that I know of
Originally Posted by jordan96xj View Post
If a vehicle that starts ok, runs for a couple of minutes ok, but then suddenly starts degrading (stalling, stumbling, hesitating) these are the hallmarks of a failing/failed upstream O2 sensor. The computer does not use the sensor for the first minute or two during a cold start. But once the computer starts relying on it (after operating temperature gets high enough) the fuel trim calculations will start to get progressively worse (because the O2 sensor is feeding bad information to the computer).
I was thinking it could be the o2 sensor....so if the o2 sensor was going/is bad would it allow it to rev up fine but then when you let off throttle it wants to die?
Anthonyfid is offline  
Old 05-12-2019, 06:57 AM
  #7  
CF Veteran
 
Join Date: May 2012
Location: Lost in the wilds of Virginia
Posts: 4,532
Year: 1998 Classic (I'll get it running soon....) and 96 (just purchased) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Default

FKPF.

Fix Known Problems First.


You know you have cracked vacuum lines. That will cause you all manner of problems. Start there. Don't go spending money or time on this or that. Fix the known problems first. THEN look at other things.


With that oil pressure I'd do a compression test, too.
BlueRidgeMark is offline  
Old 05-12-2019, 09:15 AM
  #8  
Newbie
 
Join Date: Jan 2019
Location: Henderson ,Nevada
Posts: 6
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0L
Default

Originally Posted by BlueRidgeMark View Post
FKPF.

Fix Known Problems First.


You know you have cracked vacuum lines. That will cause you all manner of problems. Start there. Don't go spending money or time on this or that. Fix the known problems first. THEN look at other things.


With that oil pressure I'd do a compression test, too.
Thatís is very solid advice. I tend to follow this exact advice myself.
Xjayingit is offline  
Old 05-12-2019, 08:33 PM
  #9  
Newbie
Thread Starter
 
Join Date: May 2019
Posts: 10
Model: Cherokee (XJ)
Default

Thanks for the advice i will be doing this sometime this week...and if anyone else had any insight I'd gladly appreciate it
Anthonyfid is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
mattphillips90
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
19
05-17-2012 11:20 PM
prerunner1982
Off-Topic Discussion
4
05-07-2010 01:25 PM
Greenebean
Off-Topic Discussion
52
06-25-2009 06:36 AM
cherokeebaby
Off-Topic Discussion
7
11-21-2008 11:57 AM

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

Thread Tools
Search this Thread
Quick Reply: Low rough idle at start.and low oil pressure once at operating temp


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description: