I recently ran a shielded, twisted pair from the cab back to the O2
sensor. In the engine bay, one wire connects to the sensor and the other to
the ECU feed. In the cab the two wires terminate at a SPST switch with my O2
monitor gadget ( http://neksiwel.20m.com/photo5.html )  always attached to
the sensor wire. This allows me to disconnect and connect the O2 sensor from
the ECU  while under different driving conditions.  The thinking here was
seeing the affects of different tuning settings (like the AFM) on the
mixture, in and out of closed loop.

   Originally , the monitor was pegging out in the rich (while in open loop)
so I started tightening the spring in the AFM to lean it out. Presently I
find that kind of rich seems to drive the best.

  The point here is I have disconnected the O2 sensor at least a hundred
times in the last week, with the ignition on and off, and can not verify any
ECU resetting affects i.e. no difference in the way the engine runs.

Ken Lewis
86 crewcab
http://neksiwel.20m.com/