Overboost Cutout, who is next?

[scott.john.mockry@bangate1.tek.com]

Bob,

I located the ECU overboost cut off  memory locations and the timing maps
in the MAC11 and MAC14 EPROM's  a few months  ago using the "detailed"  
MAC02 ECU EPROM code information that was done by RDH. 
The MAC11 and MAC14 computers use similar code to control the 
overboost fuel pump cutout and locating this code in the MAC11 and MAC14 was
pretty easy once I knew what to look for after seeing RDH's code dis-assembly.

At this point I am running my 89 200TQ with a reprogrammed EPROM that allows
 a higher overboost cutoff (1.95 bar) but keeps the factory rev limit intact.
This was done by increasing the overboost  cutoff values
from a HEX CD (decimal 205) to HEX FA (250).
The computer uses HEX values from 00 to FF (Decimal 0 to 255). With this change
the boost is controlled almost entirely by the stiffer waste gate spring with a little
assist (briefly) from the computer adding pressure on top of the Waste Gate. This 
setup works well (for now) and even prevents excessive boost levels at higher altitudes to
prevent over-reving the Turbo. The Mac11 and Mac14 ECU's have no altitude (barometric)
sensors which are used in the 91 200TQ and on the S4/S6 20V engines to lower the 
boost at higher altitudes. 

There  are some other memory locations that I "believe" contain the actual "Boost Maps" 
that the computer uses to add pressure on top of the WG spring to fine tune the boost.
Unfortunately, I have had no time (or a 86-88 5000 car) to test my theories on. 
I also have had no  time to modify RDH's dis-assembly program to do further "real" 
work on sorting out the EPROM data tables and actual assembly language instructions.

I really don't want to get in the business of modifying Audi computers cause if I did I would
have to charge a lot of $$ to cover possible liability issues (crashed cars and blown motors)
and to pay for EPA certifications and the like. Ned at Intended Acceleration provides
 ECU mods at prices that I consider "reasonable" when you consider the time it takes
to sort out the mods with testing etc and all the technical  help he provides his customers.
There is also the peace of mind that comes with his package.

In keeping with the idea of sharing information so others can benefit and learn as I did, 
I  sent this "basic" MAC11 EPROM code information to several people on this list who are 
capable of doing their own EPROM programming. (Orin, Dave L, Steve E, Graydon, RDH) 
to name a few. This group has also provided some good feedback and information at
the same time. Maybe some of these other people can provide additional information
on whether they have found the holy grail (boost maps) on MAC11 ECU's and are
willing to provide a low cost EPROM mod for others on this list.

Hope this helps
Scott M.