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Re: Type 44 Single Pass Intercoolers in US? Mac-07 ECU


>From: Todd Phenneger <phen9461@uidaho.edu>
>So how do you get 2.0 bar from KH???    I dont know of any chip
>tuners that can modify this ECu.  Scott Mockery told me he couldn't modify
>it.  or was he just atalking aobut the timing maps??  Not sure.  I spose I
>could just leave it the way it is. :-)

The Mac-07 has the timing/boost etc. data and instructions stored inside
the microprocessor (uP) in the internal on board ROM, so it is "possible"
to modify these, assuming you can suck the ROM data out and modify the
timing maps, boost maps etc. I have never looked into modifying these any
further due to very little demand. The later MAC11 ECU's had a stand alone
EPROM which contained this data and instructions.

I suspect that there are some tuners that modify these, but they may be
only using  a simple resistive divider at the output of the internal
pressure sensor to reduce its voltage output, and make the uP believe the
boost is lower than expected, which advances the timing across the entire
operating range, and would allow more boost before the cutout is reached.

A few have also used the MAC11 ECU with the KH engine, by modifying the
wiring harness connector at the ECU. If I remember correctly, the Hall
Sensor return (ground) circuit wiring needs to changed to a different pin
at the connector to work with the MAC11 ECU. 

Pin out details can be found at


The timing maps inside the MAC11 should be changed to work with the higher
static compression of the KH (8:3 to 1, vs the MC 7:8 to 1), especially
with higher boost, unless you want the knock sensor system to always
correct the timing.

Regarding the original question of the single pass Intercooler for the MC,
my understanding is only the MC-2 engine (dual knock sensor MC) in Europe
got the single pass, Phil Payne (I believe) has this MC-2 with single pass
intercooler in his wagen.

Pictures of this single pass MC-2 installation from the parts CD can be seen at


Has anyone seen a US model 1989-90 Audi 200TQ 10 valve Turbo engine with
the factory single pass intercooler?

Scott Mockry