89 xj 4.0 idle issue
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Newbie
Joined: Jun 2012
Posts: 6
Likes: 0
From: Crawlifornia
Year: 1989
Model: Cherokee
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?
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?
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,577
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,577
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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
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?

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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Junior Member
Joined: Jun 2021
Posts: 44
Likes: 7
From: Bakersfield Ca.
Year: 1993
Model: Cherokee (XJ)
Engine: 4.0 HO
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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