Help, 93 S4 loss of power and turbo whine

[Bernard Littau]

> The car is a 1993 S4.  Noticed a lack of power lately as well as
> no whine from the turbo spooling up.
>
> Suspected the bypass valve was bad and when removing it found
> that it was much easier to move the old valve than it was to move
> the new one.  "Great" I thought... only $35 from local Audi
> dealer and it was in stock.
[snip]

Interesting.  It's possible your turbo is shot.  Normally, a hung turbo
would block the air path enough to make the car run poorly if at all.
However, the bypass valve creates an alternate air path -- the valve is
normally open until boost builds.

Pull the Turbo inlet hose off and try to spin the turbo by hand.  Check for
play, too, both in-and-out, and side-to-side.  It should spin freely, have
no in-and-out play and only a little side-to-side play.

Best,

Bernard Littau
Woodinville, WA
'88 5ktq