# RPMs going up when shifting



## Steuspeed (Feb 23, 2002)

My RPMs are going up when I push in the clutch. This happens when it get cooler in the winter and when the car is cold in the morning. It goes away when the engine warms up or during the summer it seems fine. Any clues?

81 Scirocco with CIS


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## Steuspeed (Feb 23, 2002)

Looks like I have CIS Lambda with the hot start relay. I'm wondering if my cold start valve is staying on until the car warms up, thus still spraying fuel on off throttle shifts. It has also been flooding if it does not start on the first or second key turn. I pulled and reconnected the hot start relay and all the red/black wire connectors behind the fuse box. I did the same thing to the green plastic connectors in the engine compartment. It seemed to start fine and run around the block, but it's not that cold today. We'll see how it runs in the morning.


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## Steuspeed (Feb 23, 2002)

I have studied this cold start valve circuit and it looks like the cold start valve can only get 12 volts when you are turning the key to the start position. If it was still getting 12 volts you would hear the hot start relay clicking which it is not. Now I'm thinking that the start valve itself is leaking or the control plunger is sticking in the fuel distributor on throttle off shifts until the car warms up.


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## ps2375 (Aug 13, 2003)

Or maybe you can take your foot off the gas pedal when the clutch is in. Not the first time a VAG product has has "Pedal Mis-application".


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## ps2375 (Aug 13, 2003)

Steuspeed said:


> I have studied this cold start valve circuit and it looks like the cold start valve can only get 12 volts when you are turning the key to the start position. If it was still getting 12 volts you would hear the hot start relay clicking which it is not. Now I'm thinking that the start valve itself is leaking or the control plunger is sticking in the fuel distributor on throttle off shifts until the car warms up.


You said that once already.
I have only seen a plunger stick when dirty, and it didn't matter if it was hot or cold, it was stuck. And that would have to be a very leaky valve to cause the rpm's to go up, I would look for vacuum leaks before anything else.


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## Steuspeed (Feb 23, 2002)

Vacuum leak I will look for. I can assure you this is not operator error. All my cars are vintage (Alfa, Porsche & VW) require some a fair amount of skill to shift.


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## WaterWheels (Aug 14, 2005)

Just how much higher are we talking here? It is not only normal but by design that the engine idle is higher when it is cold. It needs a higher idle to stay running in the cold to overcome the added drag on the moving parts. When it warms up the idle, again by design, is allowed to drop to its “normal” speed. Also, just how long are you talking about? If say the electrical power to the auxiliary valve is not working then it has to heat by engine temperature only which can take some time. Extra fuel alone, as in a leaky cold start valve, will not raise the engine speed unless the mixture is already too lean. Extra fuel without the needed air just drops the idle and will cause a miss if bad enough (plus the tailpipe will spew black).

Just as a side note, I have seen oil build-up in the air filter box cause the air sensor to move slow or hang while cold. Once the engine bay warms up, and the oil too, the sensor plate moves freely again. This could cause additional air and fuel to enter the engine which would raise the idle.

Shifting, whether one thinks it is difficult or not or requires some type of talent or not, has nothing to do with the engine speed between the gears or at idle.


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## Steuspeed (Feb 23, 2002)

The RPMs at idle are fine. The idle is higher when cold and then drop once the engine warms up. The problem is the engine RPMs raise 500-1000 when you push in the clutch while driving. This occurs more as the outside temp gets cold in the winter. We have pretty mild winters here and I just put up with it last year. It goes away after the motor warms up. I'll check my air filter. I would also tend to agree that the sensor plate may not be moving freely when ice cold.


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## ps2375 (Aug 13, 2003)

So, if you are going down the road in gear with you foot off the gas pedal, and you push in the clutch, the rpm's go up 500-1000rpm? Or is it when you are simultaneously letting off the gas and pushing in the clutch pedal?


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## Steuspeed (Feb 23, 2002)

It will do it in either of those senarios. Believe me, when it's doing it, I make sure I'm coming off throttle before I push the clutch in to keep the rpms from rising as much as possible. It's very anoying. I would need to do a test to see if there was a difference in RPM if I was totally off throttle before pushing in the clutch, but it ran fine this morning 41 degree low today. When it gets down near freezing is when it acts up.


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## WaterWheels (Aug 14, 2005)

OK, when the motor is doing this, will the engine speed return to “normal” if you blip the throttle? About how long does the car have to sit when cold for this to start to happen, overnight, short stop or a few hours? Does the engine run fine except for this issue?

Oil build-up in the filter box seems like a possible reason here, have you looked inside for a build up of blow-by oil? Other than that I can only figure that for some reason additional air is entering the engine as a result of pressing the clutch pedal or something like the AAV is not warming fast enough and allowing the engine to idle high until it warms by engine heat.


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## Steuspeed (Feb 23, 2002)

I can't say for sure how fast it returns to normal, because when you shift in the next gear the load brings the rpms back down. Bliping the throttle only increases the rpms. Durring warm up, blipping will cause the idle rpm to drop after a couple minutes. I believe this is normal. It has to sit for a few hours in the cold near freezing, or over night. The engine runs fine except for this issue.

I experimented the other day by holding the throttle steady when I shift. This is exactly what is happening to the rpms when it's cold. It's possible that the throttle is sticking when it is cold. It could be either the cable, linkage or throttle body. After the engine warms up it returns to normal. It's warming up fast here in PNW and I doubt we will see cold temps again until next winter, so this will be tough to diagnose for sure until then.


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## VentoMKIII (Feb 24, 2008)

I am having the same problem with my car. It happens a lot in 5th gear if i give it a little gas, take my foot off the gas, and throw in the clutch. 

I Took a video of me driving in 5th gear at lower rps at a stead speed. When you watch the rps bounce up i am letting off the gas and throwing in the clutch. I do it about 4 times in the video. 


http://www.youtube.com/watch?v=gkqzKm2v7eo&list=UU0nVimCbBPk1ImyaEA5OuSQ&index=1


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## rabbitnothopper (Oct 19, 2009)

check that your throttle linkage for the secondary valve is closing

have someone operate the pedal with the car off
watch the linkage move as they slowly release it from WOT


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