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replaced injectors, bad miss

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Old Aug 18, 2014 | 10:08 PM
  #1  
Jrankin89's Avatar
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From: Mariposa
Year: 1989
Model: Cherokee
Engine: 4.0
Default replaced injectors, bad miss

Just replaced the injectors on my 4.0 il6, now I'm getting a bad miss, no leaks, plugs, wires, battery,water pump,thermastat,transmission, all sensors ,are new except the cps, any ideas? Bad injector?
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Old Aug 19, 2014 | 07:17 AM
  #2  
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From: Fayetteville, NC
Year: 1996
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What injectors did you use? Learn the computer?
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Old Aug 19, 2014 | 08:41 AM
  #3  
Jrozar's Avatar
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From: Las Vegas
Year: 1997
Model: Cherokee
Engine: 4.0
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How do you learn the computer?
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Old Aug 19, 2014 | 08:56 AM
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Fred/N0AZZ's Avatar
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From: Monett, MO.
Year: 1999
Model: Cherokee
Engine: 4.0
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Originally Posted by Jrozar
How do you learn the computer?

After a reset letting the engine run till it finds the proper air/fuel ratio for the injectors that you have installed.
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Old Aug 19, 2014 | 09:01 AM
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From: Longview, TX
Year: 1998
Model: Cherokee
Engine: 4.0L
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Disconnect battery cables and touch them together for 30 seconds. This will fully discharge the system and the computer will re-learn the proper ratio after multiple cycles.
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Old Aug 19, 2014 | 10:07 AM
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From: Fayetteville, NC
Year: 1996
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scary af in my mind to do that.
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Old Aug 19, 2014 | 10:19 AM
  #7  
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From: Longview, TX
Year: 1998
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Engine: 4.0L
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Originally Posted by crabmushrooms5
scary af in my mind to do that.
Seems counterintuitive, but works the same as disconnecting them for an hour or two. Make sure BOTH cables are off of the battery BEFORE proceeding.
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Old Aug 19, 2014 | 11:32 AM
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From: Carrollton, GA
Year: 1994
Model: Cherokee
Engine: Inline 6 4.0L High Output
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Originally Posted by crabmushrooms5
scary af in my mind to do that.

How is connecting two wires with no power running through them scary?

I just leave mine off for a few hours.
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Old Aug 19, 2014 | 04:02 PM
  #9  
cruiser54's Avatar
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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And after all that, the Renix never needs resetting or can be reset.

OP, I'm guessing you don't have an injector plugged in all the way or you busted the line from your throttle body to MAP sensor in the process of installing the injectors.
Attached Thumbnails replaced injectors, bad miss-map-tb.jpg  
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Old Aug 20, 2014 | 07:53 AM
  #10  
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From: Fayetteville, NC
Year: 1996
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spent so much time avoiding touching red and black. doing it on purpose makes me think too much
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Old Aug 20, 2014 | 12:19 PM
  #11  
investinwaffles's Avatar
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From: Tarpon Springs, FL / Denver, CO
Year: '98
Engine: 4.0 I6
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Did you check to make sure you dont have any vacuum leaks? If no, I would wager that an injector may be faulty.

Unplug each injector until you find the offending cylinder (unplug one by one, if it runs rougher than the injector was working properly, if there is no change than you probably found the misfiring cylinder)
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