RPM Surge?
06-04-2003, 01:33 PM
#1
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Location: NJ, USA
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Car Info: 2004 WRX Sedan
RPM Surge?
Sorry for all the questions lately, but has anyone else experienced this with their WRX?
I'm driving along in say 2nd gear at about 3000-3500 RPM. I push the clutch pedal all the way down (obviously after taking my foot off of the throttle, lol) and put the car into 3rd gear. As soon as I take my foot off of the clutch and go back on the throttle after upshifting, the RPM "surges" about 100-150 RPM, then settles back down. It almost seems like the clutch is slipping slightly. I know it isn't my shift timing, because I've been driving stick for over four years. I'm confused as to why this happens, especially since this doesn't occur if I rev to 4000+ RPM (done extremely rarely since I am under 1,000 miles). Additionally, I can't recall this happening to any of the WRX's I test drove, but it is possible that I just didn't notice it.
This is probably normal, and I am going to feel like an idiot. Oh well.
I'm driving along in say 2nd gear at about 3000-3500 RPM. I push the clutch pedal all the way down (obviously after taking my foot off of the throttle, lol) and put the car into 3rd gear. As soon as I take my foot off of the clutch and go back on the throttle after upshifting, the RPM "surges" about 100-150 RPM, then settles back down. It almost seems like the clutch is slipping slightly. I know it isn't my shift timing, because I've been driving stick for over four years. I'm confused as to why this happens, especially since this doesn't occur if I rev to 4000+ RPM (done extremely rarely since I am under 1,000 miles). Additionally, I can't recall this happening to any of the WRX's I test drove, but it is possible that I just didn't notice it.
This is probably normal, and I am going to feel like an idiot. Oh well.
Last edited by Chris04WRX; 06-04-2003 at 01:37 PM.
06-04-2003, 01:51 PM
#2
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My car does the same thing.
I think maybe the idle air bypass valve opens too fast, so the engine get a little extra shot of air making the rpm surge a little. At higher rpm it is not noticable because the flow rate through the bypass is not big enough to make the engine surge at higher rpm.
I think maybe the idle air bypass valve opens too fast, so the engine get a little extra shot of air making the rpm surge a little. At higher rpm it is not noticable because the flow rate through the bypass is not big enough to make the engine surge at higher rpm.
06-04-2003, 03:11 PM
#3
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Location: NJ, USA
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Car Info: 2004 WRX Sedan
Thanks a lot. I feel much better now. Out of curiosity, anyone else out there experience this too?
Originally posted by RRRKim
My car does the same thing.
I think maybe the idle air bypass valve opens too fast, so the engine get a little extra shot of air making the rpm surge a little. At higher rpm it is not noticable because the flow rate through the bypass is not big enough to make the engine surge at higher rpm.
My car does the same thing.
I think maybe the idle air bypass valve opens too fast, so the engine get a little extra shot of air making the rpm surge a little. At higher rpm it is not noticable because the flow rate through the bypass is not big enough to make the engine surge at higher rpm.
06-04-2003, 09:36 PM
#6
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Location: NJ, USA
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Car Info: 2004 WRX Sedan
I found an interesting discussion about this very topic on Edmunds.com. Read post #2017 & post #2019:
http://townhall-talk.edmunds.com/Web...@.eea2737/2016
Does that explanation seem accurate to anyone?
Thanks to everyone who has provided valuable input so far. I really appreciate it.
http://townhall-talk.edmunds.com/Web...@.eea2737/2016
Does that explanation seem accurate to anyone?
Thanks to everyone who has provided valuable input so far. I really appreciate it.
Last edited by Chris04WRX; 06-04-2003 at 09:43 PM.
06-05-2003, 09:31 AM
#7
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Location: Bay Area
Posts: 1,402
Car Info: 02 WRX wagon=dead; rollin' in a Craptastic Camry!
Originally posted by Dash777
I had that same problem and the dealership ened up replacing my clutch and flywheel.
I had that same problem and the dealership ened up replacing my clutch and flywheel.
People with the VW/Audi 1.8 turbo comment on the same type of phenomenon. The notion is that the rise in rpm's has to do with emissions programming in the ECU. When you let off the gas, a small amount of air/fuel mixture still gets delivered to the combustion chamber, this is particularly evident in a forced induction engine. Rather than allow the fuel to go out the tail pipe unburned, the fuel is burned resulting in lower emissions and a bump in engine rpm.
You can minimize/eliminate this effect by releasing the gas a split second earlier. As a bonus, your shifts will be smoother and faster.
06-05-2003, 10:21 AM
#8
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Quote:
I had that same problem and the dealership ened up replacing my clutch and flywheel
End Quote.
Did the dealer explain what was wrong with the flywheel and clutch? I can't find any logical explaination on how flywheel/clutch could play a part in this phenomenon, because everyone's account states that the clutch is disengaged when the engine surges a little.
I had that same problem and the dealership ened up replacing my clutch and flywheel
End Quote.
Did the dealer explain what was wrong with the flywheel and clutch? I can't find any logical explaination on how flywheel/clutch could play a part in this phenomenon, because everyone's account states that the clutch is disengaged when the engine surges a little.
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