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Rpm goes up and down by it self

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Old 12-11-2008, 09:24 PM
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Rpm goes up and down by it self

This had happened few times now ,when I start the car and stop at a light the rpm will go up and down between 1k and 2k. It only happens sometimes but only when I first start it. The car has 58k miles but drives perfectly fine other then this. What can it be? Will this be covered under the new 100K warranty?
Old 12-11-2008, 09:27 PM
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Has it been colder there? My car does this all the time in the winter. It's normal.
Old 12-11-2008, 09:28 PM
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its not unusual for any car to hunt for idle when started especially in the chillier months. a fully warmed car hunting for idle at a light could be a tranny neutral switch , fouled maf sensor , vacuum leak.... or mounting carbon accumulation that is about to lead to a loss of engine compression
Old 12-11-2008, 09:41 PM
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its just your car warming up...its NORMAL
Old 12-11-2008, 09:45 PM
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Its been colder 50 degrees,its just weird I didn't notice in the past winter. Glad its normal don't want spend any $$ right now.
Old 12-12-2008, 04:04 AM
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if you are in neutral and it does this, push the clutch in. if it stops it is the neutral position switch..

it happens..

beers
Old 12-12-2008, 10:55 AM
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Thanks Swoope... Didn't know that part.
Old 12-12-2008, 11:21 AM
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I know when I was at the dealer last week for the cat, they hooked it up to their computer and I have a scangauge I also use that is plugged in. After they were done and pulled it out I came out to start the car and all my gauges went nuts, so I shut the car off and had them come out and look at it, and of course like clockwork it didn't do it, but my gauge pulled a uo155 code I believe, and I can't remember what he said, but it was something stupid to deal with resetting the computer, so I cleared it and it's never done it since. My car ran fine though when it was doing all that crap so it didn't really affect anything otherwise.
Old 12-16-2008, 08:21 PM
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My 05 started doing it last winter but not so bothersome to spend money on it. This winter it is now annoying. It idles properly with trans in neutral and clutch depressed so the neutral switch was suspect. DTC was P0850, Neutral Switch Input Circuit problem.

Switch on order.
Old 03-15-2009, 01:27 PM
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Where's the switch located ? I've looked all over and no diagrams or pictures
Old 03-15-2009, 01:56 PM
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Replaced Neutral Switch. Problem solved. The switch is located forward of the shifter on top of the trans.
Old 03-15-2009, 02:11 PM
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really? what are the long term affects of the neutral switch not being replaced
Old 03-15-2009, 02:52 PM
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Crappy idle...and if it fails completely it might not start
Old 03-15-2009, 05:20 PM
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^ yup
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