I didn't get your tip about the volts and millivolts, are you referring to accuracy? As far as I know volts, millivolts, kilovolts, microvolts, dB's, mdB's ...etc are all the same as long as you use enough digits.
I have a very important question that I failed to find a good answer for on the internet, does the PCM only cares about the average of the O2 sensor voltage? or does it read different parameters in the waveform (like max, min, frequency, phase shift or delay relative to e.g. the crank sensor pulses)?
I put together a little 555 circuit to generate a square wave to feed to the computer while the 2 heater wires stay connected (made a special 6-conductor wire for this) and will see how the fuel trims react.
