Odd over-boost situation? Any BTDT's?

[Konstantin Bogach]

I would  check lower wastegate hose (from IM, fitting under idle frequency valve).  It is ofter rotten under the braided cover. And I would check ECU line for leak (small hose from far right conder of
IM, 3 small hoses, ECU line is in the middle, in 1-2 feet rubber hose is spliced with green plastic line).  Disconnect ECU line and check with vacuum pump.

Konstantin Bogach.

>
>
> Greetings all,
>
> After replacing the throttle body switch and multi-function sensor due to
> low boost, I got full boost back (1.4) on my '89 200.  Matter of fact I
> would see 1.4 at best with the throttle body switch, it was a few weeks
> later that led me to switch the multi-function sensor over a A/C
> problem.  From there I would see 1.5 boost.
>
> Anyway, with the A/C on I will see 1.5 bar fast and the car will cut out
> for a brief second leading me to believe I probably have a vacuum leak in
> the Michelin man hose or wastegate hose... however with the A/C off I can
> hit 1.5 and no cut out will take place.  Same problem still or should I
> look elsewhere?  While I'm on the boost subject, another idem pops up at
> highway speeds.  If I apply throttle and the boost shoots up to 1.3 or 1.4,
> it will fluctuate up and down .1, never steady.  Again would this be vacuum
> leak related or something else?
>
> Recent fixes include new injectors, fuel pump, throttle body switch, M-F
> sensor, radiator sensor.... mostly all original parts replaced do to age
> (13 years - 140,000 miles.)
>
> Having a hard time finding a similar problem or BTDT that so hopefully the
> experts here know :)
>
> --
> Taylor
> '89 Audi 200
> '01 Audi A6 2.7T
>