Jeep is idling weird
Thread Starter
Junior Member
Joined: Sep 2008
Posts: 98
Likes: 0
From: Flagstaff, AZ
Year: 1996
Model: Cherokee
Engine: 4.0 I6
Okay, so I just bought a '96 cherokee about a week ago, and yesterday it started idling kinda funny, theres a lot more vibration than there should be and the check engine light is on. The oil pressure gauge also fluctuates a tiny bit when the engine is idling. When the jeep is moving everything is fine. I took it to a mechanic just to ask what might be going wrong, and I think I'm going to have him find out what code the computers putting out ($20) and just figure out what I have to do from there. He quoted me $250-300 for a tuneup so I think I'll just learn how to do it myself. Does it just need a tune up or could there be something a little more serious going on?
"CF Moderator"
Joined: Sep 2008
Posts: 3,045
Likes: 3
From: N.J. Shore Area
Year: 1994
Model: Cherokee
Engine: l6 HO
Renix Super Guru
Joined: Mar 2008
Posts: 24,653
Likes: 19
From: In yourz postez fissin jurr spelinzs
Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
We have all the codes right here on CF. No need to search elsewhere.
https://www.cherokeeforum.com/showthread.php?t=3323
https://www.cherokeeforum.com/showthread.php?t=3323
Thread Starter
Junior Member
Joined: Sep 2008
Posts: 98
Likes: 0
From: Flagstaff, AZ
Year: 1996
Model: Cherokee
Engine: 4.0 I6
Thanks for the advise. I took it to a jiffy lube and they diagnosed it for me, it was something about the cylinders misfiring, but all it needs is new spark plugs and im gonna check the wires tomorrow. What spark plugs should I get for it? I know that changing out spark plugs is pretty straight forward but is there anything i should watch out for?
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First, if you look on the firewall, with the hood open, right in front of where the driver sits, there is the recommended plug and gap, on a sticker.
Second, don't just yank on the plug wires, when you pull them out. Pull on the thick part around the plugs, known as the "boot".
Third, only take off and replace one wire at a time. If you get some wires mixed up, it will SUCK to be you. Ask me how I know this....
Get yourself a plug gapper, and learn how to properly gap your plugs. This will pay off in the long run, for you.
Second, don't just yank on the plug wires, when you pull them out. Pull on the thick part around the plugs, known as the "boot".
Third, only take off and replace one wire at a time. If you get some wires mixed up, it will SUCK to be you. Ask me how I know this....
Get yourself a plug gapper, and learn how to properly gap your plugs. This will pay off in the long run, for you.
Thread Starter
Junior Member
Joined: Sep 2008
Posts: 98
Likes: 0
From: Flagstaff, AZ
Year: 1996
Model: Cherokee
Engine: 4.0 I6
First, if you look on the firewall, with the hood open, right in front of where the driver sits, there is the recommended plug and gap, on a sticker.
Second, don't just yank on the plug wires, when you pull them out. Pull on the thick part around the plugs, known as the "boot".
Third, only take off and replace one wire at a time. If you get some wires mixed up, it will SUCK to be you. Ask me how I know this....
Get yourself a plug gapper, and learn how to properly gap your plugs. This will pay off in the long run, for you.
Second, don't just yank on the plug wires, when you pull them out. Pull on the thick part around the plugs, known as the "boot".
Third, only take off and replace one wire at a time. If you get some wires mixed up, it will SUCK to be you. Ask me how I know this....
Get yourself a plug gapper, and learn how to properly gap your plugs. This will pay off in the long run, for you.
The motor just runs rough. The problem is figuring out which wire goes to which plug. It's amazing how quickly you can get your mind upside down over something as simple as that.
"CF Moderator"
Joined: Sep 2008
Posts: 3,045
Likes: 3
From: N.J. Shore Area
Year: 1994
Model: Cherokee
Engine: l6 HO
We have all the codes right here on CF. No need to search elsewhere.
https://www.cherokeeforum.com/showthread.php?t=3323
https://www.cherokeeforum.com/showthread.php?t=3323
Thread Starter
Junior Member
Joined: Sep 2008
Posts: 98
Likes: 0
From: Flagstaff, AZ
Year: 1996
Model: Cherokee
Engine: 4.0 I6
...I fixed it. I replaced the spark plugs about 15 minutes ago and was successful. I was a little apprehensive because this was the first time I've ever worked on a car in my entire life, but it worked out. It runs waaaay smoother and feels a lot better to drive. I think that the problem was caused by the ceramic part of one of the plugs breaking off, when I pulled it out it was in 2 pieces and I'm pretty sure it wasn't from sloppy wrenching on my part. Now it's time to deal with all the other little problems...
Renix Super Guru
Joined: Mar 2008
Posts: 24,653
Likes: 19
From: In yourz postez fissin jurr spelinzs
Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
Good job. If you need help with the rest of your "little problems" then just post up and we will help if we can.


