Idling control - Audi 100 '89

[David Boyd <john@dboyd.demon.co.uk>]

I recall a discussion some time ago on the List about the effects on idling
of removing the dipstick or the oil filler cap - my Audi 100 falters if the
dipstick is removed when idling and stalls if the filler cap or indeed the
crankshaft vent hose is removed. It has also just had its annual statutory
vehicle test and failed because the CO emissions are too high. I suspect the
two may be connected. The engine seems otherwise OK.

Anyone any suggestions / BTDT ? Should I be looking for a vacuum leak ?-
(none obvious).

Very grateful for any help.

Regards

David
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john@dboyd.demon.co.uk
Cumbria, UK.