rough idle jeep
Thread Starter
Junior Member
Joined: Oct 2010
Posts: 46
Likes: 0
From: eastern NC
Year: 2000
Model: Cherokee
Engine: 4.0L
hello everybody, about a week ago I posted a question about my jeep idling bad after it was run hot. Appreciate all the help from ya'll but I still haven't found the problem. These are the things I've done.
2000-jeep cherokee-I6-4wd-195K miles
1. new plugs & boots
2. new coil.
it's in the shop now and they have checked
1. compression- they said it's good and my head gasket is not leaking
2. they have narrowed it down to the #1 cylinder not firing
3. they can hear fuel injector clicking for #1 (so its at least kinda working)
4. swapped another coil on they had at the shop and no change in how it runs.
Just got off the phone with mechanic and there going to pull the #1 injector tomorrow and replace if needed. He said if this doesn't fix it he doesn't know what to do next.
If any jeep experts can come up with some other things to check it would be appreciated.. Thanks for all the help
2000-jeep cherokee-I6-4wd-195K miles
1. new plugs & boots
2. new coil.
it's in the shop now and they have checked
1. compression- they said it's good and my head gasket is not leaking
2. they have narrowed it down to the #1 cylinder not firing
3. they can hear fuel injector clicking for #1 (so its at least kinda working)
4. swapped another coil on they had at the shop and no change in how it runs.
Just got off the phone with mechanic and there going to pull the #1 injector tomorrow and replace if needed. He said if this doesn't fix it he doesn't know what to do next.
If any jeep experts can come up with some other things to check it would be appreciated.. Thanks for all the help
CF Veteran



Joined: Apr 2009
Posts: 18,786
Likes: 14
From: CT.
Year: 88
Model: Comanche (MJ)
Engine: 4.0 HO
So there is spark to the #1 cylinder and compression.
I'd have to say bad injector. if that doe's not fix it I'd pull the valve cover and check the two valve's per #1 cylinder and see if they are opening all the way.
I'd have to say bad injector. if that doe's not fix it I'd pull the valve cover and check the two valve's per #1 cylinder and see if they are opening all the way.
Thread Starter
Junior Member
Joined: Oct 2010
Posts: 46
Likes: 0
From: eastern NC
Year: 2000
Model: Cherokee
Engine: 4.0L
yeah I've got spark and good compression on cylinder 1 according to mechanic. hoping it ends up being the injector so I can get back on the road. Maybe the injector got to hot when the motor overheated? I don't know
Newbie
Joined: Nov 2010
Posts: 11
Likes: 0
From: Stafford, Va.
Year: 1993
Model: Cherokee
Engine: 4.0L
Your intake gasket is leaking air into the #1 cylinder causing it to run lean. Tell your mechanic to put the scope on it and watch the firing pattern...it should show a misfire. Then while it's idling, he should carefully spray carb cleaner around the #1 intake gasket and see if it improves the firing. Overheating may have cracked the gasket or burned out a small piece of it.
Greg
Greg
https://www.cherokeeforum.com/f2/200...-please-64548/
Good luck!
Thread Starter
Junior Member
Joined: Oct 2010
Posts: 46
Likes: 0
From: eastern NC
Year: 2000
Model: Cherokee
Engine: 4.0L
Your intake gasket is leaking air into the #1 cylinder causing it to run lean. Tell your mechanic to put the scope on it and watch the firing pattern...it should show a misfire. Then while it's idling, he should carefully spray carb cleaner around the #1 intake gasket and see if it improves the firing. Overheating may have cracked the gasket or burned out a small piece of it.
Greg
Greg
Also it was showing code 301 which is misfire on #1 cyl. I watched him unplug the #1 cyl injector and the motor did not die down, unplugged #2 inj. and the motor died down. He then switched #1 and #2 injector but it was the same deal so I don't think it's an injector issue. Thanks for help. gonna go get some carb cleaner.
I've just got the jeep back from the shop. They had done all they know to do.
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Thread Starter
Junior Member
Joined: Oct 2010
Posts: 46
Likes: 0
From: eastern NC
Year: 2000
Model: Cherokee
Engine: 4.0L
I actually watched my mechanic put a long screw driver up to the injector and he could here it running but when you unplug the #1 injector there is no change in how the motor running. He has swapped the #1 and #2 injectors to be sure and it is still misfiring on #1 cyl. Actually just got it back from the shop cause they don't know what else to do to it so if you got any ideas throw em at me. thanks
Registered Users
Joined: Sep 2009
Posts: 1,371
Likes: 4
From: morrisonville ny
Year: 2000 @ 1994 givin away
Model: Cherokee
Engine: 4.0
Is it getting fuel and shooting it into the cylinder if thats all ok then you need to check the valves like mentioned above. Its not heat soak so forget that.
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