audi 80 rev drop or engine stall when disengaging the clutch

[cd_contact]

Hello! I'm having problems with my '91 Audi 80 , 2.0 petrol ,8v , engine code AAD . When I disengage the clutch while the car is still moving the rev drop to 400-600 and sometimes the engine stops . The engine starts and idles without any problems . The only fault code I get is related to the lambda sensor . I would appreciate your help . Thanx.

[Lofty79]

sounds like the idle control valve being a bit lazy, does it sometimes catch the revs before they drop too low?

[cd_contact]

Yes . Sometimes it catches the revs ... sometimes I declutch and the revs drop to idle and not lower . Could the VSS (vehicle speed sensor ) have anything to do with my problem ? I know I'm having probmlems with the speed sensor , that's why I'm asking . The ICV on my car doesn't seem to be serviceable .

[Lofty79]

Difficult to pinpoint without a diagnostic check done, but seems all could be a possibility. Lambda sensor is another one... sorry, to add to the list. Do you know someone who has the same car who would be willing for you to swap sensors temp basis to see if they fix it, then youll know.

[cd_contact]

Unfortunately I can't find anybody with the same engine (the ICV for example is different on a K/KE-Jetronic, mine beeing Motronic). I'll change the lambda sensor (I was planning to do it , due to higher fule consumption) and see if it helps . I think it won't ...:( . Thank you .

[scotty33]

A bad lambda sensor can cause the car to run rich, this leads to the high fuel consumption, often causes the bouncing idle and stalling you are getting. As you have the high fuel consumption and the fault code, it seems it needs renewing anyway?

[cd_contact]

I changed the lamda sensor,spark plugs ,leads ,distributor cap and rotor. I cleaned the air flow meter and recentered the plate according to manual . One fault code remaining : vehicle speed sensor . I know where it's located but I can't get in out (I can only turn it clockwise for 90 degrees) . The engine doesn't stall asa often as it used to , and the revs don't drop below 800 . But at very low speeds with clutch disengaged the revs drop to 800 , stay there for a second and then the engine shuts off .Anybody succeded in getting the vehicle speed sensor out without breaking it ? Thank you .