Intermittant stall on coast-down

alan cordeiro alancordeiro at
Thu May 1 23:28:57 EDT 2003

Sounds like the bypass valve diapraghm is punctured. Its great
you got 10 years out of it, the expected life seems to be around 5 or 6.

----- Original Message -----
From: "Kevin Maloney" <kevin at>
To: <200q20v at>
Sent: Thursday, May 01, 2003 5:30 PM
Subject: Intermittant stall on coast-down

> I have a '91 200 which has begun to intermittantly stall as engine
> approaches idle rpm in coast-down situations (i.e., braking with clutch
> Promptly restarts by letting out clutch (if car still moving), or by using
> starter.  Engine is fully warmed-up when this happens.
> Had an identical intermittant stalling problem early-on while the car was
> still under warranty. It stumped the dealor, and the Audi field support
> staff, so car was eventually sent to the Audi emissions/engineering
> in Southern California (I believe Agoura or Thousand Oaks), where they
> through all the possibilities and finally located the problem, which was a
> perforated diaphram in a vacuum-operated control device they had not
> previously encountered a failure with. (I wish I could remember what
> component that was).
> Now, 10 years later, I am experiencing the same stalling behavior ... may
> may not be the same cause. My mechanic, who worked many years for the
> Audi dealor, and now is independent, replaced the fuel pump relay switch
> he had experienced this to cause similar problems), and has also gone
> through all the vacuum lines to rule-out obvious vacuum leaks.
> Recommendations on what to check or do next?
> Thanks, Kevin
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