MAC-14 voltage divider mod - how to identify?

Beatty, Robert BeattyR at
Fri Apr 27 15:52:58 EDT 2001

the way to tell if you have a 1.8 bar mod is to look at the spring inside
the wastegate.  Its quite easy to take out with 8 8mm nuts holding it in
place.  Pull the cap off the waste gate and look at the spring.  If you can
squeeze the spring closed with your hand its prolly a 1.2 spring (stock) if
you can barely compress it with your bare hand, then its most likely the 1.8

If your ecu had been fooled, it most likely would reach 1.4 and not go over
that amount as thats the value the xducer is fooled into thinking is max.
1.3 sounds like your car is working correctly.  I'm not sure what the chip
cost is for a 90 200tq but id like to know myself as im picking up a car for
my wife this weekend.


-----Original Message-----
From: Eyvind Spangen [mailto:eyvind.spangen at]
Sent: Friday, April 27, 2001 2:27 PM
To: quattro at
Subject: MAC-14 voltage divider mod - how to identify?

I suspect the MAC-14 ECU in my '90 200TQ has been a "victim" of a voltage 
divider mod, as the dashboard gauge never shows more that 1.3, it shows 0.7 
with engine off, it runs better than a 3600 lb car with 160 hp "should", and

the PO told me that it was chipped.

I opened up the ECU to take a look, and I found no home-made soldering or 
wires connected to the pressure transducer, but nevertheless the fooled up 

I understand that I need to measure the boost with an external gauge to be 
sure, but I have to get one first (will do the following week).. :-)

The wastegate looks like it has been fooled with - new diaphragm installed, 
and the whole thing looks newer than 11 years..

I guess that a 1.8 bar spring and a voltage divider of some sort has been 
installed.. If I apply pressure to the boost line to the ECU, I won't get
than 1.5 on the display, even if I feed 2.0 absolute pressure.. Looks like
divider is constructed to avoid the 1.6 fuel pump cutout..

Anyone know anything? BTW, how much does a "real" chip mod (like the SJM
run these days?


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