tuning in open loop
the closed loop to do its job. Like O2 sensors are
messed around by fresh air shoot-through or cold,
or you run something very very naughty through
the fuel system. Open loop is as stable as the hard
mechanicals (presuming enough attention to the
environmental adders/multipliers) while closed loop
can drive itself crazy chasing bogus feedback. If
pop psychology can't get its mind right, you may
need to have it committed.

