RPM climb on throttle lift?
04-13-2006 | 09:04 PM
#1
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RPM climb on throttle lift?
When I lift my foot from the throttle to shift, why do the RPMs climb slightly when I engage the clutch?
By slightly, I mean only 2-300 RPMs
By slightly, I mean only 2-300 RPMs
04-13-2006 | 09:09 PM
#3
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Originally Posted by EpsilonK
When I lift my foot from the throttle to shift, why do the RPMs climb slightly when I engage the clutch?
By slightly, I mean only 2-300 RPMs
By slightly, I mean only 2-300 RPMs
My theory:
you're disengaging your clutch so the engine is not under the load of the transmission.
Picture a wind up car when you pick it up.. don't the wheels spin faster when not on the floor.
Hope that made sense.
Last edited by soggynoodles; 04-13-2006 at 09:12 PM.
04-13-2006 | 09:17 PM
#4
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Originally Posted by soggynoodles
because your foot is on the gas.
My theory:
you're disengaging your clutch so the engine is not under the load of the transmission.
Picture a wind up car when you pick it up.. don't the wheels spin faster when not on the floor.
Hope that made sense.
My theory:
you're disengaging your clutch so the engine is not under the load of the transmission.
Picture a wind up car when you pick it up.. don't the wheels spin faster when not on the floor.
Hope that made sense.
My foot is not on the gas :-P
I read something about the stock BOV being slightly restrictive, and that causing it...but I don't care enough to get aftermarket BOV...and ricer noise to accompany, lol.
04-13-2006 | 09:21 PM
#5
Originally Posted by EpsilonK
My foot is not on the gas :-P
I read something about the stock BOV being slightly restrictive, and that causing it...but I don't care enough to get aftermarket BOV...and ricer noise to accompany, lol.
I read something about the stock BOV being slightly restrictive, and that causing it...but I don't care enough to get aftermarket BOV...and ricer noise to accompany, lol.
04-13-2006 | 09:26 PM
#6
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Most cars these days delay closing the throttle suddenly for emissions. When you lift your foot the throttle is still open. Then you put the clutch in and like soggy said the egine revs a little then starts to go down. The whole time the throttle is in the same position or less. Ignore it or disengage the clutch later.
04-13-2006 | 10:10 PM
#9
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Originally Posted by Mr. Xevious
STi ?
my 05 did that.. welcome to drive by wire
my 05 did that.. welcome to drive by wire
nah, just plain 'ol 04 wrx
Not really too worried about it, just mildly curious...
04-13-2006 | 11:10 PM
#11
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As posted above: given throttle opening plus given load.......you reduce that load, it's going to spin up slightly to equalize at first before settling back down. Keep in mind that keeping your foot off the throttle doesn't mean ther'es not an accelerative force; your IAC is always functional, and takes a moment to react, which means it's open as a secondary throttle plate until it reacts and drops to mean idle; by that point, you should already be shifted and throttling up to smooth engagement for the next gear.
04-13-2006 | 11:12 PM
#12
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Originally Posted by sybir
As posted above: given throttle opening plus given load.......you reduce that load, it's going to spin up slightly to equalize at first before settling back down. Keep in mind that keeping your foot off the throttle doesn't mean ther'es not an accelerative force; your IAC is always functional, and takes a moment to react, which means it's open as a secondary throttle plate until it reacts and drops to mean idle; by that point, you should already be shifted and throttling up to smooth engagement for the next gear.
04-13-2006 | 11:12 PM
#13
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Originally Posted by sybir
As posted above: given throttle opening plus given load.......you reduce that load, it's going to spin up slightly to equalize at first before settling back down. Keep in mind that keeping your foot off the throttle doesn't mean ther'es not an accelerative force; your IAC is always functional, and takes a moment to react, which means it's open as a secondary throttle plate until it reacts and drops to mean idle; by that point, you should already be shifted and throttling up to smooth engagement for the next gear.
04-13-2006 | 11:27 PM
#14
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Originally Posted by EpsilonK
What is IAC?
Idle Air Control
http://forums.nasioc.com/forums/show...22&postcount=1
Last edited by JON MACIAS; 04-13-2006 at 11:46 PM.