Walter -

The mixture is set based on an MP x RPM table, with additional adjustments
for intake air temperature.  The table has 8 RPM and 8 MP setpoints (making
64 points).  Points in between are, I believe, linearly interpolated.  Given
the narrow RPM operating range of a Lycoming engine, these are more than
enough points.

The points were built by me using a trial method - my airborne dyno (aka
N366B).

The system has two computers - only one fires the injectors at a time.  I
choose which one using a dash mounted switch.  One is set to run LOP in
cruise (ie. RPM 2200 to 2500 range) and the other runs ROP at all times.  I
targeted 100 LOP for LOP mixtures and 50 ROP for ROP settings.  I'm sure
they could be tweaked better.  I know I am running much richer than that
above 2550 RPM - basically my takeoff power.

Again, this is a homegrown system.  It works beautifully now - but it was a
royal PITA to set up.

Matt