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.

1989 4.0 idling problem

Thread Tools
 
Search this Thread
 
Old 08-26-2012, 08:48 PM
  #1  
Member
Thread Starter
 
DasWulf79's Avatar
 
Join Date: Jul 2012
Location: MS
Posts: 111
Likes: 0
Received 0 Likes on 0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0w/703 injectors
Default 1989 4.0 idling problem

The engine was idling fine to begin with, besides having a miss. I changed plugs, wires, cap, and rotor, then cleaned the throttle body and reinstalled with a new gasket. While cleaning the throttle body I noticed alot of carbon aroung the IAC spindle. I removed the IAC and cleaned it really good. I mean this thing was shining when I finished. When I reinstalled the throttle body and started the Jeep it started running at around 3000 rpms. I shut it of and worked the throttle a few times started it up and it started idling funny. It will idle back and forth between 500-800 rpm's. Today I checked the TPS with a volt meter and it was slightly off. I got it back to specs and restarted the Jeep. It again ran at 3000 rpms. I turned it off and again worked the throttle and restarted it, and it is still running between 500-800 rpms. I looked for a vacuum leak but cannot find one. Any ideas???
Old 08-26-2012, 08:59 PM
  #2  
CF Veteran
 
tiwvr1's Avatar
 
Join Date: Mar 2010
Location: Elizabethtown, pa
Posts: 1,030
Likes: 0
Received 1 Like on 1 Post
Year: 1994
Model: Cherokee
Engine: 5.2
Default

Triple check for vac. leaks. Make sure there are none, unhook the battery for a couple hours to make sure the comp. is reset for the cleaned IAC.
Old 08-26-2012, 09:42 PM
  #3  
Senior Member
 
67 GMC's Avatar
 
Join Date: May 2012
Location: Fort Erie, CANADA
Posts: 925
Received 5 Likes on 4 Posts
Year: 1987
Model: Cherokee
Engine: 4.0
Default

Originally Posted by tiwvr1
Triple check for vac. leaks. Make sure there are none, unhook the battery for a couple hours to make sure the comp. is reset for the cleaned IAC.
X2-Disconnect battery. Usually just 30 minutes is fine in my experience.
Old 08-27-2012, 01:09 AM
  #4  
Senior Member
 
cherokeelaredo'90's Avatar
 
Join Date: Aug 2011
Location: California
Posts: 604
Likes: 0
Received 1 Like on 1 Post
Year: 1990
Model: Cherokee
Engine: 4.0 i6
Default

The renix jeeps don't store codes....... Disconnecting the battery just resets your radio. That's it.
To the OP yes check for vacuum leaks again. Also check the exhaust manifold bolts. On my '90 one of the bolts was loose. I tightenend it up and magically it brought the idle back down.

Last edited by cherokeelaredo'90; 08-27-2012 at 01:13 AM.
Old 08-27-2012, 06:49 AM
  #5  
::CF Moderator::
 
cruiser54's Avatar
 
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,872
Received 1,526 Likes on 1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Default

Make sure your intake manifold bolts are snug.

Which side of the TPS did you use for adjustment? Flat 3 wire connector or square 4 wire?

Ever refreshed all your grounds? Some real critical stuff relies on one ground in particular.
Old 08-27-2012, 07:15 AM
  #6  
Senior Member
 
67 GMC's Avatar
 
Join Date: May 2012
Location: Fort Erie, CANADA
Posts: 925
Received 5 Likes on 4 Posts
Year: 1987
Model: Cherokee
Engine: 4.0
Default

Originally Posted by cherokeelaredo'90
The renix jeeps don't store codes....... Disconnecting the battery just resets your radio. That's it.
To the OP yes check for vacuum leaks again. Also check the exhaust manifold bolts. On my '90 one of the bolts was loose. I tightenend it up and magically it brought the idle back down.
Agreed, it doesn't store codes (no one said that), but it does reset the ECU and TCU.
Old 08-27-2012, 10:30 AM
  #7  
Member
Thread Starter
 
DasWulf79's Avatar
 
Join Date: Jul 2012
Location: MS
Posts: 111
Likes: 0
Received 0 Likes on 0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0w/703 injectors
Default

Well like I said it was running fine before the tune up and throttle body cleaning. So in theory the grounds should be fine. And also in theory the only way I should have developed a vacuum leak is if something became disconnected while I pulled the throttle body. All of that is fine, I have checked the vacuum lines about 4 times now. I am leaning toward thinking it is something associated with the throttle body since it started acting up when I removed/cleand it.
Old 08-27-2012, 02:25 PM
  #8  
::CF Moderator::
 
cruiser54's Avatar
 
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,872
Received 1,526 Likes on 1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by DasWulf79
Well like I said it was running fine before the tune up and throttle body cleaning. So in theory the grounds should be fine. And also in theory the only way I should have developed a vacuum leak is if something became disconnected while I pulled the throttle body. All of that is fine, I have checked the vacuum lines about 4 times now. I am leaning toward thinking it is something associated with the throttle body since it started acting up when I removed/cleand it.
The common denominator is the plastic tube with 2 rubber ends between the throttle body and MAP sensor.

And FWIW, if anybody owns a Renix and doesn't know for a fact that the ground refreshing has been done, they need to do it themselves.
Old 08-27-2012, 05:06 PM
  #9  
Member
Thread Starter
 
DasWulf79's Avatar
 
Join Date: Jul 2012
Location: MS
Posts: 111
Likes: 0
Received 0 Likes on 0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0w/703 injectors
Default

Left the battery unhooked most of the day. Worked like a champ. Thanks!
Old 08-28-2012, 12:13 AM
  #10  
Senior Member
 
cherokeelaredo'90's Avatar
 
Join Date: Aug 2011
Location: California
Posts: 604
Likes: 0
Received 1 Like on 1 Post
Year: 1990
Model: Cherokee
Engine: 4.0 i6
Default

Originally Posted by 67 GMC

Agreed, it doesn't store codes (no one said that), but it does reset the ECU and TCU.
Oh okay, I just figured that since it doesn't store codes it just resets itself everytime the jeep is turned off.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
rdr8887
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
33
08-08-2017 07:28 AM
Ashs1714
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
8
09-04-2015 10:14 PM
Doogluus88
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
7
09-01-2015 06:11 AM
David Chauncey Clothier
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
2
08-29-2015 09:31 PM
d00med
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
3
08-26-2015 12:33 AM

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


Quick Reply: 1989 4.0 idling problem



All times are GMT -5. The time now is 06:56 AM.