Actually the TPS cuts the O2 sensor out of the loop at idle and WOT.  The
dancing O2 sensor reading is what the sensor does on its own, it generates
it's own electricity, like a thermocouple on a LP appliance.  The O2
sensor generally won't stay hot enough at idle to give a good reading, so
it isn't used, and at WOT the injectors just run a constant duty cycle.

Gregory Smith
Olympia,WA
'84 Vanagon

> No, the ECU does use the O2 sensor at idle.  If you have one of
> Ken Lewis's little gizmos, you'd know that it dances up and
> down at idle--maybe slower than at high rpm, but still....