Proper Mixture.

[tom cloud]

>At 21:56 7/29/96, John Dammeyer wrote:
>>Tom Cloud mentioned that he had an Oxygen sensor that he monitored under
>>cruise.  It's no big deal to add a 12 bit A/D to my processor and read the
>>voltage value.  Question is.... how do I interpret this?
>>
>>I can see if there is zero O2 left then I have complete combustion for the
>>amount of O2 in the intake stroke but if I have a too rich mixture wouldn't
>>that happen anyway?
>>
>
>

The DPM that I just posted (from Hosfelt) reads nicely -- no noise.
But then, it isn't going to allow you to feed it to a micro processor.
It is true that you will get pulses with each blast of gas from each
cylinder, but a simple integrator (read R-C network) ought to fix that.

As far as knowing what it means:  I would really like to see a data sheet
on a Bosch (or other) O2 sensor.

The data I have says that the curve is extremely nonlinear, flattening
out at about .5 V / 14.7:1 A/F (stoichiometric).  Higher voltages is
richer mixture (lower A/F), etc. with 1 volt about max and 0 volt
being what you'd expect before the sensor gets hot -- except with
10 to 100 M-ohm Z-in the DPM or A/D will always see something, even
cold.  From my observation: the sensor impedance must drop after it
gets hot as my DPM stops wandering.