At 02:27 PM 5/22/98 +0200, Jochen Hampe wrote:
>Hi,
>
>I own a 1987 Vanagon 2WD, which behaves funny during warm up:
>
>- starts fine
>- engine runs initially at approx. 1200rpm (which is probably in order to
>ensure warming up of the engine)
>- if left alone, the rpm drop to the normal  ~900 after 10mins and
>everything is fine again.
>- However in the mean time the engine is stuttering and black stuff is
>comming of the exhaust. If one is driving in the 1000-2200 rpm range, the
>engine has no power and stutters and even sometimes dies. Bringing it up to
>the >3000rpm range helps.
>
>When the engine is warm, all is fine and it is running great. The Van had
>the throttle switch and the rotator recently replaced by a VW dealer. I
>assume, something with the Digifant control unit or its sensors is wrong.
>Has anybody a specific clue?
>
Sounds like it could be a faulty temp sensor (the one located near the
thermostat). It may be fooling the ECU into thinking the engine is warm when
it isn't. The other obvious possibility is a faulty O2 sensor.

-Mark McCulley