'89 200 quattro 10V, dual knock, MAC-14 questions?

[Dan Dwyer]

I'm primarily a lurker but I've got to come out of the closet to ask a
couple questions about ECU mods:


Background:

I have had a mechanical boost mod on my car for quite a while.  It is simply
a check valve hooked up to a tee-fitting on the vacuum/pressure line that
goes to the ECU.  It has no effect on the operation of the ECU when there is
vacuum in the manifold.  During boost, however, it bleeds off some of the
pressure being directed to the ECU and "tricks" it into activating the waste
gate valve to produce a bit more boost.  I don't have a stiffer spring for
the wastegate and am pretty happy to let the ECU control boost so that it
can bring it down if sensors start sending bad news and such.

I recently tried out the "resistor mod" detailed on Ben Swann's website:
http://www.homestead.com/Ben_Swann/boostin.html   This produced a hard
starting condition since the ECU was getting skewed manifold pressure
readings during vacuum as well as boost.  It worked fine for boost but I
went back to my mechanical mod to fix the hard starting problem.


Where I'm going with this:

Ben's site advises that the resistor mod done to the pressure transducer
works best when used in conjunction with a modified chip in the ECU.  This,
among other things has inspired me to investigate eeprom tuning.  I've
scavenged the archives to learn about QLCC code but could not tell if any
development work has been done to the MAC-14 eeprom.  Does anybody have
information on QLCC for the MAC-14?

I took apart my ECU to find out what kind of eeprom it has.  Here is a pic:
http://www.wsu.edu/~dandwyer/audi/pics/mac14.jpg . It is a 27128 series
eeprom but does anybody know a good replacement part number and/or
distributor?  Does any 27128 series eeprom work?  I knew that I would need a
burner/reader for eeproms so I found this link for a DIY eeprom burner:
http://www.zws.com/products/epromr2/index.html .  Would something like that
be appropriate for burning a MAC-14 eeprom?  I hope so 'cause I already
bought the parts.  Should be a fun project in any case.

I also need to socket my ECU so I can play with different eeprom burns.  It
seems like it would be very tough to desolder the eeprom without overheating
it or pulling traces or something.  I think I would be safer just cutting
the eeprom out and desoldering the individual pins left in the board.  Does
anybody have a MAC-14 eeprom dump so that I don't have to worry about
preserving the stock eeprom when preparing the board for a socket?

Any feedback on my hastily outlined strategy would be appreciated.  I'm
learning as I go about this eeprom business.  My research has only brought
me this far and I'm sure that if I get through this, making sense of eeprom
code will probably be daunting.  I don't know whats wrong with me, I think
I'm going through blown head-gasket withdrawls.  Back in the good ole' days
with the '83 non-intercooled 5000T I could blow head-gaskets all day long
without much effort.  Now, I have to burn these new-fangled eeprom thingys
to blow stuff up.  In any case, thanks in advance for any answers or advise
anybody can give on any aspect of this project.

Dan
'89 200TQ Wagon
'85 4000Q (sold)
'83 5000T (rip)