S5 Turbo II...

OK, after a whole lot of replacing parts and fixing any and all problems. There is one left...

When I put the car into gear (any gear) the idle drops, bounces and sounds like its running on one rotor. Is there a sensor or any wiring that could be causing this? The clutch is still pressed in, so there is no load on the motor still.

anyone have this problem?

 

The neutral switch is related. Being in gear or out of gear changes idle speed (I assume through the BAC). What RPM does the car idle at, and does it drop when you put it in gear?

 

I have this exact problem. When I push the clutch in and put it into a gear, (without letting the clutch back out) the idle hunts back and fourth from 500 to 1300.... I checked the clutch swith (the white thing with a spring the clutch pushes into) and it is working properlly. However sometimes I have to push the clutch in a couple times to get the car to start as if the neutral safety switch isn't working properly. Any help would be apreciated.

 

jump it and see if it still does it

 

Bouncing/hunting idle is almost always a TPS or vacuum leak issue. I'd say the changes in idle speed associated with having/not having the car in gear just make it evident. TPS would be my bet. I've had the idle speed bounce around shortly after cold starts, and then go away after playing with the TPS a little.

The neutral switch is on the transmission, near the 5th gear/rev switch. The clutch switch is not the same thing.

 

I have no BAC or any emissions, just to add that.

I fixed the in gear idle problem. I clutch pedal sensor was unplugged. I usually do that so i can start the car without pressing in the clutch. Normally i work on the car by myself and start it from outside the car... so i plugged it back in, and the in gear idle problem was fixed. Car still is acting a little funny.

I did not set the TPS after replacing the Throttle body. I left it as is. So im pretty sure after i adjust the TPS a little, all will be fine...

 

graveyard bump

anybody know where to get a replacement clutch pedal switch. I am talking about the one at the top of the pedal.

Mine doesn't work correctly because the cruise control doesn't cut off when you push the clutch in. I also have an issue with the idle dropping when you put it in gear with the clutch pushed in

 

The upper switch called the Interlock Switch has zippity to do with the cruise control. That's the swtich with a large black/green and a black/red wire on its connector (harness side).

IF the clutch interlock switch is disconnected..........the starter can't work, so I don't understand one of the posts above that says he disconnects it so the car will start without putting the clutch in.

The switch on the lower part of the clutch pedal that has a Yellow/Black Yellow wire is the one related to the cruise control.

The other clutch switch (on the lower part of the pedal) that tells the ECU that your in gear, is colored Y/L and black/yellow.

Something like that. I probably misread the thread.

INterlock is on the fwd side of the pedal...........the other two are on the aft side of the pedal...clutch pedal.

 

On my S5 vert, the switch for cruise is on the top end of pedal travel (clutch engaged, foot not on pedal area). The starter interlock switch is down on the floorboard.

 

This. I am looking for the switch at the top of the pedal (foot off clutch). I had to replace the little plastic piece on my s4t2 that pushes that switch in. The pedal on my s5 pushes the switch in but it doesn't work

 

To those that come across this in the future. The clutch switch that is pressed when the clutch is released is serviceable. On mine the spring broke causing the plunger to not close the circuit when the clutch was depressed. To fix this you just need to bend back the 4 tabs on the back of the switch (near the connector end) pull it out and clean the contacts and replace the spring. I don't have any specs on the spring so just eye ball a good one.

Repaired it and now the car behaves much better. No more random hunting idle while warming up and no drooping idle once warmed up

 

i seldom have this issue. after cold starts too but goes away after it warms up.. only if i have the car in gear and the clutch down tho.

 

Take a 17 mm wrench and take out the switch at the top of the clutch pedal (when it's released) and then use a multimeter to test if the switch works

If the switch doesn't work take it apart and see if the spring failed. Replace the spring or shim it or something so it moves up to contact the two metal pieces.

When testing with a multimeter if the switch is all the way out (plunger fully extended) it should be a complete circuit. If it is pushed in it should be open circuit.

 

You fix one thing and something else goes wrong. These cars are so stingy hahah