Resolved! (5KT stall at idle)

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <E0y03cd-0002v5-00@iglou.com> "Douglas Hurst Quebbeman" writes:

> I for one would be very interested in knowing the purpose of this 
> vacuum line on an '85 5kt. First thought was you'v got a bypass
> valve and didn't know it. Second thought is that the ECU is measuring
> MAP at the IC instead of at teh manifold.

Is it one of the lines feeding the wastegate frequency valve?

Basically, the WGFV needs low pressure and high pressure air to control the 
wastegate.  Normally, low pressure air is tapped off the turbo input and high 
pressure air off the back of the manifold.

There is a running change in the MB engine, somewhere between my car and John 
Robinson's (ca. 200 later in the build sequence).  On mine, high pressure air 
is tapped off the unthrottled boost air via the special channel cast in the 
underside of the inlet manifold that also feeds high pressure air to the 
jackets around the injectors.  On John's car, this is plugged and high pressure 
air is taken from the inlet manifold proper - i.e., throttled air.
 
I wonder if there was a version of the MC that used unthrottled air, and got it 
from the IC?

-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club