Any CIS-E III experts?

Eric S scirocco at
Fri Oct 29 21:05:05 EDT 2004

Ok guys, my saga with the new 88 90Q continues.

Massive intake leaks found and fixed (warped intake manifold if you would
believe it was one of them)

New O2, coolant temp sensors (both)

Timing belt, cap, rotor, wires, plugs, ignition timing dead on.

Sounds like it should run like a top now, right?  Nope, 2 codes left:

Wide Open Full Throttle Switch

Mass Air Flow

The throttle switch has to be in the wiring or the brain itself, all tests
check out per the bentley, but the ECU does think the full throttle switch
is being triggered constantly.  (verified this with the DPR test)  I have
managed to get the DPR to read around 0 while running (compensating for
the fact the ecu is trying to go full rich by adjusting the air flow plate
position).  So, I am left with a high idle that the ecu keeps pulling down
(up down up down).  And a car that is rather sluggish.

The Air flow error really sucks, those potentiometers should not be messed
with and are EXPENSIVE.  Same unit used on VWs CIS-E Motronic...had my
nightmares with those.

So, my questions:

Anyone run into the full switch senario before, even though the switches
all check out?  What did you do to solve?  I'm about to unplug the ECU and
start checking continuity at the pins to the connector at the TB.

The Mass mechanic (whom so graciously "assists" me in my
work at his shop) suggests I ditch the CIS-E III infavor of the older,
simpler CIS-E from say a Quantum Syncro.  He believes we can just swap the
fuel dist and plug in the Quantum ECU to the CIS-E III harness and it will
work perfectly.  Anyone done it?  Can you verify we won't have to swap the
whole wiring harness?  Considering that potentiometer is NOT a seperate
replaceable part and you have to order the whole bottom half of the air
flow sensor plate, at $600, I am very interested in ditching this stupid


1981 Scirocco S (TDI swap project)
1988 Audi 90 Quattro
1990 Corrado TDI
1991 Cabriolet (2.0 crossflow 8v project)

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