knock sensor

[jondee86]

Most OEM narrow band O2 sensors "switch" at 0.45V to indicate a change
from rich to lean. That is 0.45V = AFR14.7 ot Lambda 1.

The wide band controller synthesises an output that "switches" at the same
0.45V value by creating a steeply rising output at Lambda 1. The factory
ECU is quite happy with this, as it only needs to know if the AFR is rich or
lean. It maintains an average AFR by constantly enriching and enleaning
the fuel by a very small amount.

Kind of a cool trick, and said to be good for the catalytic converter.

Cheers... jondee86