92 4.0 Jeep revving up after stopping - have to keep foot on brake - JeepForum.com
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Unread 07-02-2008, 10:28 PM   #1
variable
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92 4.0 Jeep revving up after stopping - have to keep foot on brake

So this friend of mine has an automatic 92 cherokee 4wd with the 4.0 HO in it and for some reason when she comes to a stop light, 15-20 seconds later the engine will start revving up and she'll have to hold the brake down really hard to keep it from moving. It also I guess does it when she's in neutral and will rev up to like 2000 rpm and just stay there. I've poked around and only found a few things that hint maybe at the master cylinder, but I'm skeptical. Anyone see this before?

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Unread 07-02-2008, 10:58 PM   #2
jc052685
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idle air control valve?!?!
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Unread 07-02-2008, 11:12 PM   #3
balloo93
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Quote:
Originally Posted by jc052685 View Post
idle air control valve?!?!
That would be my guess as well.
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Unread 07-02-2008, 11:21 PM   #4
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Or toasted brake booster... 2000 rpm is low enough it also could be a normal vaccum leak.

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Unread 07-02-2008, 11:34 PM   #5
xjpro
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If your idle control valve is serviceable, just take it out and give it a good clean with carburetor cleaner.

Hope this helps!
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Unread 07-03-2008, 12:09 AM   #6
variable
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I couldn't find any vacuum leaks, and it its very inconsistent as to when it happens, i.e. not very often so I haven't actually been able to reproduce it myself. But I'll look into the idle control valve.

Thanks guys!
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