4.0 ZJ intermittent stumble in idle - JeepForum.com

 
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post #1 of 7 Old 08-23-2013, 11:12 PM Thread Starter
JaneLee
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1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond
Posts: 35
4.0 ZJ intermittent stumble in idle

funky issue and no solutions in sight. i have a 94 4.0 I6. it has an intermittent slight stumble in P or N but RPM is normal. As soon as you put it in any gear the RPM drops to about 5-600, stumbles and acts like it wants to die. Cleaned the throttle body and butterfly, replaced the TPS, MAP sensor and IAC. No vacuum leaks, all injectors working with no leaks there, fuel pressure is normal at 33psi. No change in running with or without O2 screwed in so i don't think it's the CAT and CAT has no rattle at all. It wont make to a shop so i can get it scanned. Any suggestions?

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post #2 of 7 Old 08-24-2013, 06:17 AM
newfieZJ
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1995 ZJ 
 
Join Date: May 2008
Posts: 6,557
Start by cleaning your grounds .

Re-seat all your fuses and relays everywhere , and your PCM connection . Clean as needed .

Clean battery terminals

Consider pulling the crank sensor and cleaning it . It's a magnetic pick up and it picks up small metallic debris . Could be a weak signal .

If your check engine light(CEL) is on , use the key method to retrieve codes . Key to on(not start) off , on , off , on . Then the codes will blink via the CEL by blinking . Blink blink blink space blink blink = code 32

Try this first , it's free . If no luck , post results .
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post #3 of 7 Old 08-24-2013, 09:28 AM Thread Starter
JaneLee
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1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond
Posts: 35
throws no codes, just start and stop 12-55. battery term clean. pcm?
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post #4 of 7 Old 08-24-2013, 01:20 PM
Oldfrog
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2007 WK 
 
Join Date: Feb 2008
Location: Louisiana/Texas
Posts: 5,092
Merely unscrewing the o2 sensor will not give you the desired results for a test. Disconnect it from the connector.

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
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post #5 of 7 Old 08-24-2013, 02:07 PM
ZeeJay1997
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1997 ZJ 
 
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Posts: 8,710
Quote:
Originally Posted by Oldfrog View Post
Merely unscrewing the o2 sensor will not give you the desired results for a test. Disconnect it from the connector.
good catch oldfrog. aren't we fixing the same jeep in another thread?
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post #6 of 7 Old 08-24-2013, 02:22 PM Thread Starter
JaneLee
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1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond
Posts: 35
probably lol had internet/puter issues. mine went down and had to borrow being i'm stranded in another state
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post #7 of 7 Old 08-24-2013, 02:25 PM
ZeeJay1997
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1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,710
disconnect o2 sensor. the connector should be under the manifolds
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