Re: chip

[Robert Houk - WorkGroup Server Firmware <Robert.Houk@East.Sun.COM>]

Any further netwisdom out there? I was just asked this question;
following is my reply.


					-RDH


   i have a 85´ urquattro (WR), and my ECU is MAC 01 !!
   can i use your chip in this european model ??

I have no idea.

I think -- but am not at all sure -- that the MAC-02 is a proper
superset of the MAC-01 (i.e., I think the MAC-02 is a MAC-01 with
extra stuff, in particular, the mixture-control "frequency valve"
output).

The ECU connector is the same, but I don't know if the pinout is
the same. If it is, and the ECU's microprocessor is the same
Motorola 6802 (actually, it's a Hitachi, I don't remember the
chip number, but it's a 6802-compatible CPU), then I would guess
(and it's only a *GUESS*) that the units are basically compatible.

If so (and this is a *GUESS*), then I suspect that my (i.e., the
MAC-02) code running in a MAC-01 would be "unhappy" since it can't
read the O2 sensor (you don't have the O2 / Oxygen sensor mounted
in the exhaust system, do you?), but that only affects the mixture
control, which the MAC-01 also doesn't have, so I don't think it
would matter; similarly the block-temperature is only used to affect
the cold-engine warm-up mixture, which would be all static on your
engine (as I understand it); the ignition timing, fuel-pump drive, 
and manifold pressure reading would likely all work "normally", so
the net effect would be that the MAC-02 code would run "OK" in the
MAC-01.

If you can dump the MAC-01 ROM (if you can successfully extract it
from the ECU circuit board without destroying it...), there should
be a marked similarity between it and the MAC-02 code. In particular,
the first 256 btyes should be very very similar (probably not dif-
ferent by more than a "few", say 2 to 4); the last 4 words (16-bit
quantities) should look something like:

  FFF8:	F500=62720
  FFFA:	F400=62464
  FFFC:	F400=62464
  FFFE:	F400=62464

If you in turn go to the referenced addresses (remember that "F500"
means offset 0x500 [500 Hexadecimal] into the ROM chip itself, you
should see (for a little ways) a very similar code sequence. If
that turns out to be the case, then I would again *GUESS* that the
MAC-02 code would likely "work" in the MAC-01.

If you go ahead and try my MAC-02 code in your MAC-01, I'm pretty
sure that you would not immediately damage the engine. If they're
incompatible, the most likely thing is that it just won't work, the
engine won't start (no ignition to the coil/sparkplugs) and/or no
fuel pump power.

If it is going to work at all, it would most likely either start
right up and idle happily, or not run at all. It is of course 
possible that the timing is calibrated sufficiently differently
that it will run like shit (pardon my French...) and be immediately
obvious even at idle that it is "not right".

If I were to try it, I would run the engine normally, get it nice
and warmed up. Then I would swap the chips and see if it immediately
restarts and idles with the MAC-02 chip in place. If so (appears to
work "normally"), then I would very cautiously drive it around a bit
to see if it appears to continue to run normally. I would very
carefully start driving it a little more aggressively, watching the
boost to make sure it doesn't do anything too wild (the ECU doesn't
have any control over the boost, so it's more how the ECU is reacting
to the boost -- it shouldn't shut down or anything under normal boost
levels), listening carefully for engine knock to make sure the ignition
timing is not too aggressive (nor too retarded, killing the performance
of the engine). If all that checks out, I would then try increasing
the boost (springs, bleeding pressure to the wastegate, whatever) to
see how it behaves. VERY CAREFULLY. If all appears normal, let it sit
overnight, then see if the cold-start behavior is normal.

My best recommendation would be to compare the stock MAC-02 code to
your MAC-01. I would think there should be many marked similarities,
with most changes being "new" stuff appearing in the MAC-02 code.

Then note the differences (there's only a few, if you count the first
256 bytes [the ignition timing map] as "one change") between my code
and the stock MAC-02 code, and try applying just those few changes
(one a time, of course!) to a copy of your MAC-01 code, testing each
"edit" out to quantify/verify its effect.