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Unread 04-25-2011, 06:00 PM   #1
sernaeric
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1987 YJ Wrangler 
 
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87 YJ Accelerates when its on Idle...

Whats Up Guys!! I just bought my 2.5 YJ and it recently started to accelerate on it's own while the jeep is on and on idle. It goes up to 2000 RPM's and scares the hell out of me because there is nothing I can do to stop it or bring it down, so I just end up turning the engine off. I checked the accelerator cable to see if it was sticking but it is not nor is the pedal. Any ideas out there of what could be causing this and how to fix??

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Unread 04-25-2011, 08:11 PM   #2
moonshinefuel
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So after you shut it off, and start it again, it idles fine?
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Unread 04-25-2011, 08:59 PM   #3
Jeepin_XJ_101
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Is it a stick shift? I didnt think they made auto's for the 2.5 until later. If it was an auto it would make sense that it pulled forward at 2K RPM so you would only have to figure out why its shooting up that high (you would have to anyways), but with a stick and it pulls forward you may be having issues with the slave cylinder or clutch system.
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Unread 04-27-2011, 09:35 AM   #4
sernaeric
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Thanks for the replies! Its not an Automatic and when I shut it off and turn it back on, the RPMs go up right away. I means It was driving fine up until a few days ago.
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Unread 04-27-2011, 09:47 AM   #5
Michaelgoesrawr
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Quote:
Originally Posted by Jeepin_XJ_101
Is it a stick shift? I didnt think they made auto's for the 2.5 until later. If it was an auto it would make sense that it pulled forward at 2K RPM so you would only have to figure out why its shooting up that high (you would have to anyways), but with a stick and it pulls forward you may be having issues with the slave cylinder or clutch system.
Couldn't a vacuum leak cause a high idle too?
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Unread 04-27-2011, 09:49 AM   #6
JFcavedweller
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does it rev up when you are in neutral? or just in gear?
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Unread 04-27-2011, 03:25 PM   #7
sernaeric
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Revs up when i'm in neutral. Also when i come to a stop and I take it out of gear....
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Unread 04-29-2011, 12:43 PM   #8
sernaeric
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So I checked all my vacuums and they are all in tact. I downloaded a diagram online so I followed that. Other than that is still doing the same thing... now it just idles on 2000rpms.... its rediculous...
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Unread 04-30-2011, 09:43 PM   #9
Jeepin_XJ_101
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Quote:
Originally Posted by sernaeric View Post
So I checked all my vacuums and they are all in tact. I downloaded a diagram online so I followed that. Other than that is still doing the same thing... now it just idles on 2000rpms.... its rediculous...
If your vacuum lines are all in tact and not leaking then its probably the TPS (throttle position sensor). You can take some carb cleaner and spray it around the intake and manifold or any of your other hoses and if the idle drops when you hit the area with cleaner then there is your vacuum leak.

Oh I think I get it now, when you say it accelerates on its own then you mean the RPM's kick up, not that the actual jeep accelerates forward, I take back my comment about the clutch system
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*SOLD*

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
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Unread 05-01-2011, 10:20 PM   #10
klrstew
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My 92 has a fluctuation as well. Idles at 1100 which sounds a little high anyways and often revs up to 1500 for no apparent reason and sticks there for about 2 mins. This seems to be pretty common, but my searches are not going well. Yes, i'm a noob!
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