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Re: S4 turbo pressure measurement

I'm going through a similar problem with my '92 S4 right now.

Before starting the car, the gauge should read 1.0 - 1.1, depending on
calibration, altitude, etc.

If decelerating, no gas feed I get between 0.3 and 0.4.

At idle it normally runs at 0.4 - 0.5 once things are up to temp.  Normal
driving, steady state speed (freeway) it usually runs around 0.8 - 1.0 unless
going up a hill, then it goes to 1.2 - 1.3, depending on conditions.

Under "duress" (when you haven't exceeded the 15 seconds permitted by the
factory for overboost) you should get it to 2.1 - 2.2 without any difficulty
whatsoever.  I recently looked up the original road tests from Autoweek and
Car & Driver for the '92 intro of the car.  The Audi engineers referred to
the overboost condition as a temporary "fighting mode", who said they didn't
have a sense of humor?

At any rate, I'm now having problems getting above 1.8 bar, had the dealer
look at it, they cleaned the valving and tightened vacuum connections -
things were back to normal for a day or so. Now they're back down to the 1.8,
and an ocassional 2.0.  But the 2.2 is gone, for now.  This makes a big
difference in the acceleration.

I'd have you mechanic look it over.  If you just purchased it and it has any
kind of warranty - go have it checked out.  It definitely is not normal!  You
should easily get to 2.2 bar.

Good luck!  Bill