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Discussion Starter · #1 ·
ok so here is the problem, I start my 4cyl TJ and it usually rev's hi for the first couple of seconds then drops to about 500 rpm's. over the past two days the standard revs its idleling at is about 2500. what is going on do I need to adjust something or what? has anyone else had this problem??? I have used lucas injection cleaner so I don't think its my injectors but what the hell do I know.:chair:
 

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Drives by Braille
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when you first start it up?

Did the check engine light come on?

Does it idle normal after warmed up?
 

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Discussion Starter · #3 ·
when it first starts up it idle's high. no check engine light. and it idles high even after it has warmed up (off and on).

it will stay at a high idle for a little bit then drop to normal only to pick back up to a high idle around 2k or 2.5k
 

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Drives by Braille
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But it drives ok?

Sounds like the Idle Air Control valve to me. Try cleaning it with some throttle body cleaner, and if that doesn't do it, it might need replacing.
 

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Discussion Starter · #5 ·
right...idle air control valve...where is that again? lol sorry.

it drives ok just when I put the clutch in it goes back to a high idle.
 

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idle air controlle valve x2:D It's on the side of the throttle body.:D
 

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Discussion Starter · #8 ·
well I got some TB cleaner and sprayed and wiped off the inside, it didn't work and was still reving high. so I did the next best thing to fix the problem...I drove the shit out of it :D for some reason it fixed itself, its reving back around 500rpm at idle and driving fine still so I don't know what the deal is with it but I think its time for a full tune-up and maybe a trip to the mechanic.
 

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Discussion Starter · #10 ·
I know, I know, its a bad word to utter. the really bad thing is there really isn't any good ones around here, and dare I mention going to the place that starts with a "D" and ends with "ship."
 

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Knows a couple things...
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The IAC is located on the passenger-side of the throttle body and is held in place with two T-25 torx bolts. Unplug its harness then remove it, it's pretty easy to get it off. Then use a rag or toothbrush together with either carb cleaner or throttle body cleaner to gently clean all the black gunk off the IAC's plunger. Then use a small diameter brush (like a baby bottle nipple brush) to clean the oriface in the throttle body that the IAC's plunger fits into. Then use the rest of the cleaner to clean the inside of the TB per the instructions on the TB cleaner can.

If this doesn't take care of the high idle, then you've got a bad throttle position sensor. They get dirty inside and cause idle/throttle response problems. But the throttle position sensor can't be cleaned, it can only be replaced... $40-something to buy and is replaced just like the IAC. :)
 

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Fields of pain is where I graze
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Sorry off topic, but Jerry how long have you worked on jeeps?
 

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Discussion Starter · #13 ·
I will look into that when I get off work tonight. I hope thats all it is. but then again I'm always looking for something new to buy :D .
 

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Sorry off topic, but Jerry how long have you worked on jeeps?
I've only worked on my own Jeeps but my first Jeep was an '89 Cherokee, the wife has had two Grand Cherokees, and I bought my '97 TJ back in '96. With 171,000 miles on the TJ, I've seen most of the issues they can have. :)
 

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Discussion Starter · #15 ·
:D well thats good to know ^^ :D
 

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He just always seems to have a very detailed answer. :)
 

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Discussion Starter · #17 ·
yes, yes he does. but all and all its appreciated.
 

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Discussion Starter · #18 ·
ok so I replaced the IAC valve, but didn't help much, now its idleing at about 18K. I'm so confused. could it be that I'm runnning the 4.0L TB? I dono...HELP PLEASE! :crash: :confused:
 

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ok so I replaced the IAC valve, but didn't help much, now its idleing at about 18K. I'm so confused. could it be that I'm runnning the 4.0L TB? I dono...HELP PLEASE! :crash: :confused:
18,000 :eek: :eek: :eek: Crap a 4 liter that thinks it's an F1 engine!

A similar issue happened to my 03. Sometimes it would idle at 1500 and sometimes 500. All mine was, was a sticky throttle linkage. I used some brake clean to clean it and sprayed it with pure silicon lube. Fixed.........hope yours is something this simple.

Hutch
 

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Discussion Starter · #20 ·
18,000 :eek: :eek: :eek: Crap a 4 liter that thinks it's an F1 engine!

A similar issue happened to my 03. Sometimes it would idle at 1500 and sometimes 500. All mine was, was a sticky throttle linkage. I used some brake clean to clean it and sprayed it with pure silicon lube. Fixed.........hope yours is something this simple.

Hutch
oops I guess that would be a little high huh...lol:doh: its running about 1,800 rpms at idle and goes up and down its really weird and I'm getting really frusturated. I can start the jeep up just fine and it will idle about 800 for a few min then it kicks up to 1,400 then bumps to about 1,800-1,900 a few min later. would you have some pics of where exactly I should spray?
 
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