rev hang on shifts

[5ktq]

This car is a little odd compared to other VAG DBW cars I've driven (1.8T GTI, 1.9 TDI golf, 2.7T A6, etc).

When I punch the clutch it's often really pokey dropping the revs, which is more noticable on the low gears. eg 2->3, especially when you've got it up to 4 or 5k at the start of the shift. Have to wait around 2s for it to drop enough to let the clutch out if you don't want to lurch a bit.

All the other cars you have to shift fast, or give it a bit of gas as they drop down to idle like a ton of bricks.



Looking around this can be the clutch switch, but mine works (cruise works, and shuts off when you hit the clutch). In old cars I've had this problem when there is excess metered air getting past the throttle, so i cleaned the throttlebody, aligned it, no real improvement. PCV system has all been recently replaced, so it shouldn't be getting any extra through there. When sitting parked, revs fall off the same whether you are pressing the clutch or not. Is it possible a PO could have coded the ECU as automatic or something? Maybe the switch is defective but I tried cruise on and off a few times today and didnt seem to notice any glitching.

Any other ideas? Think maybe the coolant or air temperature sensor could do it? It might be a bit better when the engine is cool.

I'm tired of shifting like a grandma


hmm could the uhh... N80? (whatever the evap purge solenoid is) being stuck open do it? That wouldn't be metered air though, would it, so I'd think it would behave more like a vac leak (and maybe throw a code).

Last I checked the trims, idle was ~1% and mult was maybe 3%, so I don't think I have any serious boost/vac leaks (and I went over most of the system).

[MetalMan]

It's possible the clutch switch is working intermittently. Mine would occasionally rev-hang... eventually it threw a fault code (no CEL). You can watch its operation using VCDS, and confirm when the switch engages, and whether or not it registers every time you press the clutch pedal.

Could also be a vacuum leak as you indicated. A boost leak test is a sure way toward diagnosing that.

[Charles.waite]

It's possible the clutch switch is working intermittently. Mine would occasionally rev-hang... eventually it threw a fault code (no CEL). You can watch its operation using VCDS, and confirm when the switch engages, and whether or not it registers every time you press the clutch pedal.

Could also be a vacuum leak as you indicated. A boost leak test is a sure way toward diagnosing that.

My b7 had a similar issue but the rev hang seemed intermittent. Replacing the clutch switch seemed to help.

[5ktq]

Well for the price I might just change it I guess.

Suppose I could try replacing it with a paperclip and see if it is improved (cruise shouldn't work then, though.)

[Charles.waite]

In my research the ECU uses the signal from the beginning-of-throw clutch switch to cut spark or something and allow the revs to drop, since you're shifting. As well as disabling cruise. I don't think paperclipping it will diagnose it in any way, and might just really confuse the ECU.