KISS System

[Howard Wilkinson]

I advertized for sale a very simple mechanical fuel injection system
the other day which has only 2 control inputs.  One is airflow, the
other engine temp.  No RPM input, no throttle position input, no
vacuum input, no exhaust O2 feedback loop, Just airflow and temp.
    This system worked very well, was efficient, and very drivable
which suggests to me that this in enough information to do the job
well.  The objective after all is to maintain a given air fuel ratio.
It seems to me that if one could mimic this type of system the program
necessary to control the injection should be very simple.  The control
of fuel flow in this system is accomplished by designing the taper of
the servo throat so that it works correctly.  Because of this design
the injection system is not going to be adaptable to a wide range of
engines.  However if a airflow sensing servo were designed with a
constant taper throat, it should not be difficult at all to devise a
simple lookup table for each position.  Cold operation could be
accomplished outside the computer control system in exactly the manner
that Bosch did in this system.  By varying the resistance (mechanical)
against the servo arm using regulated fuel pressure from a temperature
controlled regulator.
    I may be stupid about electronics, but it seems to me that most of
the EFI systems out there are way too complex.  Anybody out there
building a KISS EFI system that doesn't require operator intervention?
H.W.