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89 xj 4.0 idle issue

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Old Sep 6, 2015 | 01:10 AM
  #1  
Calikingcrawler's Avatar
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From: Crawlifornia
Year: 1989
Model: Cherokee
Default 89 xj 4.0 idle issue

Ok so I got the Cherokee for free from my dad 2 1/2 years ago with its share of problems. Went thru the just of it new icm, coil, cap, rotar, plugs, wires, oil, rear main seal. Had it slogged and it passed with flying colors. Had some issues with a nostart about a year ago. Pulled the iac and cleaned thurally with no fix. Finally got a tip to unplug the cps and reconnect. Tried that and she fired back up. Been my daily driver ever since 100 miles a day. I drove it this morning running normal as always. Parked then went to move it this evening and it wouldn't start. Tried the tcm trick and no luck. Finally got it to start enough to get it to the garage (barely) feathering the throttle. I did some searching, cleaned the iac again and no luck. Sprayed a lot of the vacuum lines while running to see if idle changed with no luck.
Here is where I am at with it. I can get it to start I have to keep the rpms at or above 1500. If I let off it will die with the occasional sputter shake like crazy misfire run for 10 seconds then die.
Then I unplugged the vacuum to the map sensor and it idles smooth revs fine and returns to about a 900 rpm idle. Put finger over vacuum line going to map sensor and it is getting vacuum from throttle body. But as soon as I plug the vacuum back into the map sensor it peters out and dies again.
Would this be a bad map sensor or an underlying problem making the map take the fall.
Please help I have 2 days to fix this before work.
I would think if it was the cps it wouldn't even start.
I'm at either map, tps, or iac. Anyone wanna take a swing at this?
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Old Apr 28, 2017 | 08:30 PM
  #2  
gstank's Avatar
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From: Central OR
Year: 1997
Model: Cherokee
Engine: 4.0
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Did it end up being the map, tps or cps?
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Old Apr 29, 2017 | 08:57 AM
  #3  
cruiser54's Avatar
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by gstank
Did it end up being the map, tps or cps?
I doubt you'll get a response after 2 years.

And actually, there is generally no "silver bullet" cure for these issues. Most are common, but not the same.

Post up what issues you are having.
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Old Apr 30, 2017 | 10:01 PM
  #4  
gstank's Avatar
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Joined: Apr 2017
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From: Central OR
Year: 1997
Model: Cherokee
Engine: 4.0
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Originally Posted by cruiser54
I doubt you'll get a response after 2 years.

And actually, there is generally no "silver bullet" cure for these issues. Most are common, but not the same.

Post up what issues you are having.
I was having issues similar before winter hit but went away for a little when I replaced the IAC and cleaned out the TB. Started acting up again (twice) about 2 weeks ago before she went in for the 702 recall. I recently found your tips and have only done 1,2,3,5&11. Hopefully 4 will bring luck. Didn't have an issue with the resistance from the TPS but will do 6 just to prevent further issues
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Old Apr 30, 2017 | 11:14 PM
  #5  
cruiser54's Avatar
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Joined: Aug 2011
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by gstank
I was having issues similar before winter hit but went away for a little when I replaced the IAC and cleaned out the TB. Started acting up again (twice) about 2 weeks ago before she went in for the 702 recall. I recently found your tips and have only done 1,2,3,5&11. Hopefully 4 will bring luck. Didn't have an issue with the resistance from the TPS but will do 6 just to prevent further issues
Excellent plan
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Old Sep 3, 2019 | 01:40 AM
  #6  
Cumminscale's Avatar
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Joined: Sep 2019
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Model: Cherokee (XJ)
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Originally Posted by Calikingcrawler
Ok so I got the Cherokee for free from my dad 2 1/2 years ago with its share of problems. Went thru the just of it new icm, coil, cap, rotar, plugs, wires, oil, rear main seal. Had it slogged and it passed with flying colors. Had some issues with a nostart about a year ago. Pulled the iac and cleaned thurally with no fix. Finally got a tip to unplug the cps and reconnect. Tried that and she fired back up. Been my daily driver ever since 100 miles a day. I drove it this morning running normal as always. Parked then went to move it this evening and it wouldn't start. Tried the tcm trick and no luck. Finally got it to start enough to get it to the garage (barely) feathering the throttle. I did some searching, cleaned the iac again and no luck. Sprayed a lot of the vacuum lines while running to see if idle changed with no luck.
Here is where I am at with it. I can get it to start I have to keep the rpms at or above 1500. If I let off it will die with the occasional sputter shake like crazy misfire run for 10 seconds then die.
Then I unplugged the vacuum to the map sensor and it idles smooth revs fine and returns to about a 900 rpm idle. Put finger over vacuum line going to map sensor and it is getting vacuum from throttle body. But as soon as I plug the vacuum back into the map sensor it peters out and dies again.
Would this be a bad map sensor or an underlying problem making the map take the fall.
Please help I have 2 days to fix this before work.
I would think if it was the cps it wouldn't even start.
I'm at either map, tps, or iac. Anyone wanna take a swing at this?
I had the same issue it was the fuel pump not enough pressure for the injectors. I was driving down the road and all set in start acting up on me what do everything ignition electrical down up is your mom was putting out low pressure I'll try that first.
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Old Sep 3, 2019 | 07:16 AM
  #7  
Jimbo Slice's Avatar
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Joined: Sep 2014
Posts: 560
Likes: 18
From: U.P. MI
Year: 1989
Model: Cherokee
Engine: 4.0L
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Fascinating.
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Old Sep 7, 2021 | 01:25 AM
  #8  
Calikingcrawler2's Avatar
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Joined: Jun 2021
Posts: 44
Likes: 7
From: Bakersfield Ca.
Year: 1993
Model: Cherokee (XJ)
Engine: 4.0 HO
Default

For anyone having this issue my fix was probably way easier than it could have been. Ended up being the hose from the pump to the bulkhead on the tank fell off. Pushed it back on and hose clamp. Whala. This was after hrs it testing and pressure testing.
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Old Sep 7, 2021 | 07:14 AM
  #9  
cruiser54's Avatar
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Joined: Aug 2011
Posts: 43,971
Likes: 1,577
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Default

Fairly common. Be sure to use hose intended for being submerged in gasoline. Must be ethanol compatible and high pressure.


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