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IAC? or TPS?

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Old May 26, 2010 | 10:04 AM
  #1  
yorkite's Avatar
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Year: 1987
Model: Cherokee
Engine: 4.0
Default IAC? or TPS?

Hey all, for the second time now, when I started my '87 this morning, the rpms went all the way up to 2100-2200, as usual, and wouldn't go down.
When this happened a couple months ago, I unplugged the IAC, and that fixed it. Not the case this morning, I had to put it in gear and kill it with the clutch, then unplug the battery for a minute. This is only the second time this has happened. Any thoughts? Jeep specs are off to the left.
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Old May 26, 2010 | 11:31 AM
  #2  
00jeepXJ's Avatar
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From: Kalamazoo, MI
Year: 2000
Model: Cherokee
Engine: 4.0L with throttle body spacer and cold air intake, bored throttle body, #784 injector upgrade
Default cleaning

Sounds like your IAC is dirty. You can clean it by taking your throttle body off and taking some time to really get in there and clean it out with the right kind of cleaner. Get some carb and choke or brake clean at worst. If you can find mineral spirits that works really good also. See if that helps you out because some times they just get really nasty in there and like to act up.
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Old May 26, 2010 | 11:35 AM
  #3  
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From: Coeur d' Alene, Idaho
Year: 1998
Model: Cherokee
Engine: 4.0 rebuilt w/ bored TB, banks header, upgraded ignition, 3 row rad, high flow h2o pump, 180* t-stat
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i assume you replaced the IAC a couple months ago when it did this (you should have, if not, do so now) so it shouldnt be dirty already, if the problem persists, unplug the TPS and see if the RPM's drop back down. if so its the TPS...
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Old May 26, 2010 | 06:24 PM
  #4  
yorkite's Avatar
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Year: 1987
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Originally Posted by 00jeepXJ
Sounds like your IAC is dirty. You can clean it by taking your throttle body off and taking some time to really get in there and clean it out with the right kind of cleaner. Get some carb and choke or brake clean at worst. If you can find mineral spirits that works really good also. See if that helps you out because some times they just get really nasty in there and like to act up.
I will try that and see if it works...Thanks.
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Old May 26, 2010 | 06:32 PM
  #5  
yorkite's Avatar
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Year: 1987
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Originally Posted by tannerp89
i assume you replaced the IAC a couple months ago when it did this (you should have, if not, do so now) so it shouldnt be dirty already, if the problem persists, unplug the TPS and see if the RPM's drop back down. if so its the TPS...
I should have mentioned that when this happened, I tried unplugging the IAC and the TPS at the same time because doing just one did nothing. I have an extra of each I grabbed at the last junkyard run, and will clean them like 00jeepxj says and wait to see if it will happen again.
The throttle linkage isn't sticking, I know that much.
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Old May 26, 2010 | 06:34 PM
  #6  
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From: Watha,NC
Year: Jeepless at the moment
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get the EFI safe cleaner, less chanc eof messing it up and not knowing
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Old May 26, 2010 | 06:55 PM
  #7  
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From: Amarillo, TX
Year: 1988
Model: Cherokee
Engine: 4.0 with bolt-ons
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Mine was doing the same thing and it was a dirty TPS
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Old May 26, 2010 | 08:22 PM
  #8  
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From: Stafford,VA
Year: 1998
Model: Cherokee
Engine: 4.0
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unplugging it wont drop the idle if the pintle is stuck open.
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Old May 27, 2010 | 03:19 PM
  #9  
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Thanks to all for the help!
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