Misfire troubleshooting - JeepForum.com
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post #1 of 3 Old 07-25-2013, 01:16 PM Thread Starter
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1996 XJ Cherokee 
Join Date: Jul 2013
Location: Roseville
Posts: 1
Misfire troubleshooting

Greetings Fellow Jeep Lovers!

I'm seeking some advice since I am a novice at working on my Jeep. I've had it for about 6 years. All that I have learned about working on engines is owed to having my Jeep. I have a 1996 (although my code reader doesn't work on it so I'm assuming it's really a 95 1/2), Cherokee, inline 6, 4.0L

I took my Jeep on a approx. 60 mile highway run and when I came to a stop it began to idle roughly. Almost as if it was going to stall and the Check Engine light came on. I promptly returned home. I hooked up my code reader which failed to communicate, thus thinking she really is a 95 1/2 Jeep. I took her to AAMCO so they could pull the codes for free. Mind you, she ran much better on the streets but still a little rough idle. I did have to gun it once (road rage) and got a puff of black smoke out of the tailpipe. The following codes were pulled: P0171 (lean at bank 1), P0172 (rich at bank 1) and P0306 (cylinder 6 misfire). I changed the spark plugs, spark plug #6 smelled like it has some gas on it. I used a volt meter to check the fuel injectors and they were all reading around 15 ohms.

Does anyone have any great advice before I start shelling out cash to replace parts here and there to find out what is wrong??

THANK YOU!! in advance!

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post #2 of 3 Old 07-28-2013, 09:41 AM
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1989 YJ Wrangler 
Join Date: Nov 2010
Location: Sin City
Posts: 2,881
O2 sensors?? Have they ever been changed. Bad readings will mess with mixture settings.

89YJ 2.5L TBI, AX-5, NP231 SYE, Ford 8.8, Yukon Grizzly, Tom Woods Shaft, 33" BFG T/As, 4" lift, Warn VR10000s.

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post #3 of 3 Old 07-28-2013, 04:29 PM
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1990 MJ Comanche 
Join Date: Oct 2009
Location: Prescott
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How about wires, cap and rotor? They're due for replacement every 30,000 miles.

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