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RPM's bouncing up and down ?

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Old 11-11-2007, 11:38 PM
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Default RPM's bouncing up and down ?

Is this normal or is it a problem. When i'm getting off an exit on the highway and i put my car in neutral the rpm's contuinisly bounce from 700rpm to 1400rpm ? It doesn't necessarily have to be getting off an exit, just when i'm rolling with it in neutral above like 30 mph.
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Old 11-12-2007, 12:14 AM
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I've never experienced that. It doesn't seem normal. when I put my car in neutral at any speed, the rpms just drop....but never bounce back up.
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Old 11-12-2007, 12:22 AM
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Yea its weird, it seems to do it more often when i'm going over 30 mph. Also i have a manual tranny just to make that clear. I have a intake, a header, a s-pipe, an a exhaust too. I don't know.
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Old 11-12-2007, 12:30 AM
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No check engine light currently with the header/exhaust?
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Old 11-12-2007, 12:32 AM
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Nope, i did the nonfouler mod for that.
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Old 11-12-2007, 12:40 AM
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Could be a bad throtle position sensor, or MAF, these things happen. Or perhaps a vaccum leak, somewhere.
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Old 11-12-2007, 12:49 AM
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Originally Posted by parkw06tc
Could be a bad throtle position sensor, or MAF, these things happen. Or perhaps a vaccum leak, somewhere.
I was thinking these things also but wouldn't it surge like it is all the time?
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Old 11-12-2007, 12:53 AM
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MINE DOES THE SAME THING... it drops then goes back up to the same 1500 rpms.. but depends on how fast ur still rollin..i think its normal...
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Old 11-12-2007, 12:54 AM
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my car does the exact thing but i also have a lightwight flywheel which is prob causing mine...does your's also do it worse when its cold?
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Old 11-12-2007, 12:57 AM
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wellll all cars do that when its cold since the rpms havent drop under 1k rpms yet...so thats why when u put it in neutral it drops where it was since it was cold over 1k rpms..
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Old 11-12-2007, 01:01 AM
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It's hard to tell if it does it more in the cold.
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Old 11-12-2007, 01:06 AM
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yea but like i said mine does the same thing even when its not cold...when i drop it in neutral it drops, then goes up..but i think never passes 2k rpms even when im rollin 40-50..
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Old 11-12-2007, 01:08 AM
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mine has been doin this for about 1 year now.. and i am all stock engine wise.. so i gess its normal.. nothing else changed.... cept the rattles but thats a whole other issue..lol
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Old 11-12-2007, 01:10 AM
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Mine does the same thing. It is totally stock and has done it from day one and still does it after 34,000 miles. It will eventually settle at idle around 700rpm. But it firsts drops to about the 1500 and then bounces for a while then eventually settles to idle after about 15sec.
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Old 11-12-2007, 01:11 AM
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Originally Posted by fujita_TC
yea but like i said mine does the same thing even when its not cold...when i drop it in neutral it drops, then goes up..but i think never passes 2k rpms even when im rollin 40-50..
True, mine i don't think has ever reved past 1500 rpm's
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Old 11-12-2007, 02:08 AM
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So i guess thats just how these engines act then.
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Old 11-12-2007, 02:09 AM
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correct so dont worry..
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Old 11-12-2007, 02:15 AM
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Cool, Thanks everybody for responding so quickly.
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Old 11-12-2007, 03:17 AM
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I've been meaning to post this for a while cause mine does the same thing. Glad to hear I'm not the only one!!!
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Old 11-12-2007, 04:06 AM
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IAC valve..
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