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Unread 12-11-2011, 08:58 AM   #1
dunderrat
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2000 XJ Cherokee 
 
Join Date: Dec 2011
Posts: 11
RPM spikes at highway speeds
We have a 2000 GC and had something odd happen during a road trip yesterday. While at highway speeds (60-70) the tach would hold steady at 2000 rpm but would sporadically spike up 100 to 200 rpm. When this happened the speedometer dropped about 1 mph each time. It would do this with and without cruise control turned on. It also seemed to do it most on flat or slight downhill stretches when there was less load on the engine. Other than this issue there is no noticeable change in engine performance. Any ideas?

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Unread 12-11-2011, 09:06 AM   #2
seu83
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2002 WJ 
 
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Location: Erie, PA
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Any howling or any strange noises when this happens. It almost sounds like the tranny is slipping while it's in od. I used to have a camaro that did the same thing. If it was above a certain rpm it wouldn't do it but when it kicked in to od it would start to slip and the rpms would jump a little. Take it for a ride without od and see what it does.
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Unread 12-11-2011, 09:17 AM   #3
dunderrat
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No, there wasn't anything else unusual or any odd sounds. It would do it more often at speeds closer to 70 MPH.
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Unread 12-11-2011, 09:29 AM   #4
seu83
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Is this the 4.7 or the 4.0 and how many miles?
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Unread 12-11-2011, 09:57 AM   #5
dunderrat
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4.0 with 145,000 miles.
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Unread 12-11-2011, 10:09 AM   #6
imaguy3
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2004 WJ 
 
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that sounds identical to what my Jeep was doing a couple months ago, the rpms would go up for just a couple seconds like it was slipping in and out of overdrive...

replaced TPS and all is good. Try it, it's cheap easy and will probably fix your problem, if it doesn't fix your problem it's at least cheap and can't hurt.
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Unread 12-11-2011, 10:29 AM   #7
dunderrat
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I'll check that out. Am I correct that it should be replaced with a Mopar and not something aftermarket.
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Unread 12-11-2011, 10:48 AM   #8
seu83
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Yes, it should be a mopar part. The first time I replaced tps on my jeep it cost 200 because first I bought one off of ebay(junk), then autozone, and finally the mopar one. The mopar one was the only one that fixed it.
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Unread 12-11-2011, 10:58 AM   #9
imaguy3
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Quote:
Originally Posted by dunderrat View Post
I'll check that out. Am I correct that it should be replaced with a Mopar and not something aftermarket.
I'm taking my chances and I used an autozone one (I know I know), but been no problems for 6 mths...

Rockauto has good prices too
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Unread 12-11-2011, 05:35 PM   #10
Bluefish94
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I'm sure a stupid question when I get the awnser but what is the TPS? Mine does the same thing now and again.
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Unread 12-11-2011, 05:43 PM   #11
the88thpianoman
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Throttle position sensor.
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Unread 12-11-2011, 06:38 PM   #12
Bluefish94
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Thanks.
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