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3000 RPM idle in 89 cherokee

Old Aug 15, 2012 | 09:45 AM
  #1  
jimfrazer777's Avatar
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Year: 1989
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Engine: 4.0 Lorado
Default 3000 RPM idle in 89 cherokee

I have read threads and tried a lot of things and cant find an answer. TPS is not problem sprayed all connections. throttle body clean. anyone have new ideas?
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Old Aug 15, 2012 | 10:18 AM
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From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
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On your intake manifold near the front is a tower shaped thing with 2 vacuum lines coming off it, one goes to tje fuel pressure regulator on the rail rhw other to your egr solenoid. If they are both rotted and leaking it could cause high idle but idk bout 3k rpm idle
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Old Aug 15, 2012 | 03:55 PM
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Year: 1990
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Originally Posted by jimfrazer777
I have read threads and tried a lot of things and cant find an answer. TPS is not problem sprayed all connections. throttle body clean. anyone have new ideas?
How have you determined that the TPS is not the problem?
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Old Aug 15, 2012 | 07:46 PM
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Year: 1990 - 2000
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Idle air controller died in open position.
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Old Aug 15, 2012 | 08:25 PM
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From: Key Peninsula, WA
Year: 1997
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Does it whistle?
Loose intake manifold bolts can cause a big vacuum leak and high idle.
Been there - done that.
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Old Aug 15, 2012 | 09:25 PM
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Originally Posted by notop46
Idle air controller died in open position.
I've never seen an IAC cause that high of an idle.
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Old Aug 16, 2012 | 07:41 AM
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Year: 1990 - 2000
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Mine was 2500 rpm when it died. I do not know if it was wide open or not. The point is, the engine is getting more air than it should with the throttle closed. Check the butterfly, iac, and for big vacuume leaks.
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Old Aug 16, 2012 | 10:39 AM
  #8  
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Year: 1990
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Originally Posted by notop46
Mine was 2500 rpm when it died. I do not know if it was wide open or not. The point is, the engine is getting more air than it should with the throttle closed. Check the butterfly, iac, and for big vacuume leaks.
That was my next thought, a warped butterfly could easily do this methinks
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Old Aug 16, 2012 | 10:59 AM
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Year: 1995
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Engine: 4.0 HO
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i'd start by checking for vaccuum leaks.

http://www.crankshaftcoalition.com/w...g_vacuum_leaks
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Old Aug 16, 2012 | 12:12 PM
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Year: 1989
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Default fixed

OK found out that the IAC was frozen. Sprayed with silicone around edges and let it sit for an hour and it loosend up. Saved 85 bucks. Still need one but for now Idle back to normal. For now.Thank you all for your help. Now to fix the Death wobble at 50 mph. New Track bar didnt help. Bushings look worn. Oh well back on the road.
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Old Aug 16, 2012 | 12:22 PM
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NICE! such a nice feeling, solving a problem thats been giving you hell.
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Old Aug 16, 2012 | 03:10 PM
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Originally Posted by stock95sport(for now)
NICE! such a nice feeling, solving a problem thats been giving you hell.
And without just throwing expensive parts at it, too.
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Old Aug 17, 2012 | 09:43 AM
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Year: 1995
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Originally Posted by cruiser54
And without just throwing expensive parts at it, too.
exactly! My other car is a Saab.....complicated diag, PITA part replacement, and very expensive parts (anything is huge $) mean when something breaks, ill just part the sum***** out!
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