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HELP!! Wierd Revving issue

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Old Apr 8, 2010, 08:25 PM
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HELP!! Wierd Revving issue

Well this is a little hard to explain.

My car has an issue to rev up on its own when i shift gears. For example: I'll be cruising along in second gear, I'll get on the throttle and when i go to shift at say 6K RPM, I'll depress the clutch, let me foot off the gas, and the revs will shoot up anywhere from 500 to 1500 rpm (at times bouncing off the rev limiter).....without me touching the gas....

At lower RPM's it's less apparent. If i shift as say 3500rpm, the Rpms may shoot up 200rpm.

Just wondering were to start with this issue.....could it be a vacuum leak somewhere? or some other issue?

I've cleaned the throttle body cause i thought it could be gummed up...I've checked the throttle cable to make sure that it isn't binding somewhere...and it seems to be fine...


Help
Old Apr 9, 2010, 12:19 AM
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Common I'd say problem, but I think the cars were designed to do it, considering the number of people who report it. It can be tuned out, if you have your car tuned. Much nicer afterwards!
Old Apr 9, 2010, 12:36 AM
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Sounds like your foot timing. Let off the gas a slight second before you push in the clutch.
Old Apr 9, 2010, 04:29 AM
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It's not the tune as it never did this before.....and its def not my foot timing.... as again this hasn't happened before, and now its a reoccurring problem.
Old Apr 9, 2010, 08:23 AM
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I have seen this problem on a local evo, I was able to ajust one of the tables in the rom to help ajust this out. Have you made any changes recently to the car?
Old Apr 9, 2010, 08:27 AM
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I have this same issue, and finally figured out how to force it to happen. I'll be taking my car to EvolutionDynamics to tune this out in a week or so.
Old Apr 9, 2010, 08:42 AM
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No changes have been made. At one point i cleaned the TB because i though maybe it was gunked up and therefore not closing properly. This seemed to help the problem last year when i did it. But when the problem re occurred this year, and i cleaned it again the problem didn't go away.

All the couplings are tight that i can see. I could see it being the tune except it never happened this bad before. I'm going to look for Vacuum leaks around the TB.

It seems that the issue varies (as was mentioned before) at if shifted at 3K RPMS it may only "blip" a couple hundred RPM's between shifts. But then brought up to 5K+ RPM's it can jump as high as 1500RPM's causing it to bounce off the rev limiter.
Old Apr 9, 2010, 01:12 PM
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sounds like your clutch could be slipping.
Old Apr 9, 2010, 02:37 PM
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No not the clutch, this happens before engagement. I'm thinking TPS...maybe....i'll have to hook up a multi meter to find out.
Old Apr 9, 2010, 02:45 PM
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boost/vac leaks can cause it, incorrect idle settings in the tune can cause it
Old Apr 9, 2010, 11:59 PM
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Tried a couple things, seems to only happen under boost. The more boost i build the more the rev's will jump......
Old Jan 18, 2014, 03:16 PM
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Did you solve the issue? I have the same problem right now. I've tried different BOVs but it's always the same.. The only thing that comes to my mind is to re-tune the ECU..
Old Jul 9, 2016, 03:49 PM
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Originally Posted by Krotom
Did you solve the issue? I have the same problem right now. I've tried different BOVs but it's always the same.. The only thing that comes to my mind is to re-tune the ECU..
Any body fix this rpm jumps before, when clutch was pres in on wot? Its hapining on my evo 9
Old Jul 9, 2016, 04:21 PM
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search "throttle hang"... that may be your issue.
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