Stock CIS, running out of gas at 2 bar?

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

In message <199710231746.KAA13201@mail1.teleport.com> "Scott M." writes:

> I was doing some testing yesterday on my 89 200TQ where I
> measured the voltage output from the CIS Air-flow plate
> potentiometer (used for fuel mileage calculation). This
> potentiometer (variable resistor) tells the dash computer
> how high the air-flow plate rises while you are driving. 

I've seriously considered using this measurement for a number
of reasons, most recently determining precise plate position at
idle.

> With the ign. key on and the air flow plate pushed up by
> hand to the top of its travel (max air flow) the voltage
> output was 4.465 V. 

There is a service tool for moving the plate by calibrated
amounts - VAG 1348/1A.  It's documented in a supplement to the
MB service manual. 

[volts snipped.  I'll post my own later.]

> The later dual knock sensor MC engine does show a different
> air flow sensor plate assembly than what was used on the
> early MC engine (86-88 5000TQ, 89 200TQ). The fuel
> distributor heads between the early and late MC engines
> have the same Bosch part number although the replacement
> rebuilt head for the late MC does not have the internal
> fuel pressure regulator plunger installed. 

Doesn't the early MC use the external valve?  The MB does -
the internal fuel pressure regulator has been replaced by
a disc on the end of a rod to seal the chambers.

> I remember Ned quoting that the stock fuel injection was
> good to 300-325 HP, at this point, I think that figure may
> need to be reduced a bit.

I've often been told by tuners that the stock MB head is
operating near to the limits of its performance.

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