It's all relative...

The TDI and most other modern turbo
engines uses a MAP or Manifold Absolute Pressure sensor.  So, in an
absolute vacuum the ECU will see 0 mbar - at sea level on an average day
you will see 1000mbar and at the top of a mountain it will be say 900mbar
- these values are all with the engine off.  So the ECU controls
boost using this MAP sensor - for a stock ALH TDI this is 1950mbar for
maximum boost, which if you compare it to the outside air pressure, it
will be higher in a mountain than at sea level, but in effect, it is the
same amount of pressure on the inside of the manifold.

David
Marshall

http://www.hasenwerk.ca
Box 4153, Quesnel BC,
Canada V2J 3J2

Engine Conversion FAQ -
http://www.hasenwerk.ca/faq

On Tue, July 1, 2008 16:04, Mike
Miller wrote:
>
> All,
>
> When I had an
02 TDI I was told the turbo produced more boost than the
> engine
was set up for at sea level. This allowed full power to 5000 feet
> where the boost no longer had to bled off.
>
>
Also told the 944 turbo Porsche was set up the same way.
>
> Anyone know is this is true and if it's true for the TD engines?
>
> Mike
>