Turbo Conversion Gone Bad - MAC 11C Troubleshooting

[scott thomas]

I thought the MFTS has to be connected. Well, I'd try to connect is
anyway. Next, I'd verify the engine timing. Use the flywheel mark
and not the crank pulley. Make sure it lines up with the cam, then
line it up with the distributor. Sounds like something that happened
to me. The timing was of, but the engine still ran, so it was the
last thing I checked.


---- Begin Original Message ----

From: blarson at Zeiss.com
Sent: Wed, 27 Aug 2003 08:47:33 -0500
To: quattro at audifans.com
Subject: Turbo Conversion Gone Bad - MAC 11C Troubleshooting


All,

My friend and I need help troubleshooting an error on the MAC 11 in
his
80tq.  Background: The car is a 1990 Audi 80Q converted with a 1987
MC
motor and MAC 11C ECU.  The code light is hooked up to the brown
connector
under the dash of the 80.  When I pull codes it comes back with 4444
(no
faults).

Problem:  The fault light comes on as soon as you start cranking the
motor
and stays on when running.  As a result the computer is running in
limp
mode (low boost).

Troubleshooting to date:
1) Swapped knock sensors, check continuity to ECU and started car
with
knock sensor out of block.  No effect.
2) Verified function and readings of air temp sensor, coolant temp
sensors
to ECU.  Correct resistance and readings at ECU.
3) Swapped MAC 11 with another known good ECU.  No effect.
4) Checked WOT switch resistance readings.  PASS.  Note this unit
what
taken apart and resoldered as well.
5) Shorted terminals 2 & 3 at WOT to make wastegate frequency valve
run.
PASS.

Any suggestions of what I should try next?  What signals is the MAC
11
looking for when cranking the motor?  It is getting some reading it
doesn't
like from some sensor when cranking.  Could it be a bad ground
somewhere?

If you can think of anything else I should try it would be greatly
appreciated.

Additional question: With a turbo conversion is it necessary to hook
up the
wires to the brake light switch and multifunction temp sensor (over
temp
input).  Other guys I know have not hooked these wires up.

Thanks







---- End Original Message ----




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