Re: High Altitude Turbo Bar Question

[John Cooper <Jacques.Noir>]

At 13:56 07/24/96 +0000, you wrote:
>Hi,
>
>I live and drive my '87 5KCSTQW at about 5500' or more in the Ft. Collins 
>and surrounding areas in Colorado. The most I've ever seen my turbo boost 
>go on the dash display is 1.1 bar.

I would call the service mgr of your nearest Audi dealer and ask what you
should expect to be the normal boost indicated.  I'm sure your car has a
waste gate in the turbo circuit, meaning that you should get the same boost
limit no matter where you are in altitude (barring balloon and space shuttle
flights).  You may have a defective boost pressure sending unit for the dash
computer, if it isn't part of the ECU sensing system.  Or your turbo isn't
funtioning, as 1 bar is atmospheric pressure at sealevel.
Maybe a stuck wastegate.

>I was wondering if this might be just a function of the atltitude. I was 
>wondering what others at altitude have experienced.
>
>Here is a bit more info which might help:
>
>1. When I turn the car on, after (or before?) it says OK, it ususally says 
>the boost is at .7 or .8.
>
MAP at an idle should be .4 to .5 bar here in the Front Range (I'm in
Boulder).  This is the normal operating manifold pressure if your idle is
around 850 rpm.  Or at least that is what my 200 TQ20V shows, and as there
is no boost at an idle, this is usually a universal figure.

>2. In normal driving, the display shows .3 up to 1.0 when I'm climbing a 
>hill or accelerating.
>
>Two (or three) associated questions:
>
>1. Is it possible the display is not showing accurate reading? My MPG 
>display usually shows I get 4-5 MORE MPG than I actually get.

The MPG figure generated by the dash computer is just a good guess.  I have
yet to find one that is closer than a couple of MPG, and can be off as much
as several.  There are calibration switches that are used to deal with
compensating the computer.  

>
>2. Where and how might I begin to look/listen for leaks?
>
>3. Any other thoughts?
>
>Thanks again to all,

Hope this helps,
Coop, in Boulder