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Old 01-28-2014, 07:17 AM   #1
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High idle questions, Newb here!!!

So i bought this 98 wrangler the other day for a steal (3200, 140,000 on it and has 3k parts in it!!!) SO bought it and immediately fell in love. When I bought it the idle would be sitting high until warmed up? It's like 5 degrees here right now and usually when it warms up like after 20-30 minutes and I stop and put it in nuetral sometimes it will slowly rev down to 900 rpm. Now I am wondering what is causing this to sit at 2k rpm idling? When I am in first or any gear it can go down to 1k or stall if I let it so it is not stuck on 2k rpm. Wondering if anyone has this issue also? Anything would help I would love to fix it myself because this is the reason I bought it! Thanks!!!


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Old 01-28-2014, 07:44 AM   #2
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Sounds like a vacuum leak. Could be the intake gasket and when the motor warms up it swells and slows the leak down. I always spray carb cleaner around the intake and vacuum lines while it's idling. And if the idle changes suddenly that's the spot that is sucking air.

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Old 01-28-2014, 08:30 AM   #3
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Yeah that is what people around here have been telling me, Ok I will try that. Am I looking for it to jump up with the carb cleaner or idle down. I am assuming a higher faster rpm.
Thanks a lot.
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Old 01-28-2014, 09:46 AM   #4
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I just had a similar problem with my 95 YJ 2.5. It would start to idle at 2000 to 3000 rpms after warming up. Turned out there were two missing bolts on the exhaust manifold and one broken off. Plus the gasket was partially gone. All this caused a major vacuum leak and the idling problems. Good luck.
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Old 01-28-2014, 09:51 AM   #5
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Quote:
Originally Posted by mudlife101 View Post
sounds like a vacuum leak. Could be the intake gasket and when the motor warms up it swells and slows the leak down. I always spray carb cleaner around the intake and vacuum lines while it's idling. And if the idle changes suddenly that's the spot that is sucking air.
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Old 01-28-2014, 10:34 AM   #6
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Ah ok cool. I will check this out too. Guess I will have to do some serious searching. Anyone got a easy method like using carb cleaner to tell where the leak is?
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Old 01-28-2014, 03:05 PM   #7
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Carb cleaner should bog the motor down. It's not as combustible as say brake clean. Brake cleaner will make it rev up but also can start a fire so we always use carb cleaner. Just start by spaying a little in the air intake to see how the motor response to it. Then spray all the way around the intake where it bolts to the head and in nothing happens start spraying vacuum connections
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Old 01-29-2014, 09:28 AM   #8
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Thanks Mudlife101, Will do!!
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Old 01-29-2014, 04:18 PM   #9
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No problem. Let us know if you find anything out.
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Old 01-31-2014, 12:11 PM   #10
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Ok so I found out what it is. After going to Pepboys and getting a free read it said that it was a vaccum leak which was odd because previously there wasn't and issue. Also it was going back down to 900rpm once in a while and was even fine for a day. Well it kept going up to 2200 and I decided I couldn't figure it out (I am not too mechanically inclined which is why I bought this jeep to learn myself) so I took it to my mechanic which always gives me a straight up and free inspections and such. He said it was the Idle control was bad. The throttle body needed to be taken off to even get to it. So I guess it wasn't the lines ? It still is a vacuum leak problem but my question is so the idle control was bad so what were the main issues and what would happen if I was to let that go? (Already fixed but just wondering ) Thanks guys for the help!!!
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Old 01-31-2014, 05:29 PM   #11
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That's a new one to me. So I'm not for sure unless it was dirty. I don't know a lot about them. But glad you got it fixed.
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Old 02-02-2014, 02:29 PM   #12
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Just fixed a similar problem with my 93 YJ 4.0L. My throttle body, butterfly, etc was gummed up bad. Took it off, used a whole can of C-foam and made it look like new. Also ended up replacing my TPS (was causing check engine light to come on). Runs great now!
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Old 02-02-2014, 07:33 PM   #13
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FYI, you have a TJ, not a YJ.

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