O2 Volts

[CLsnyder]

----- Original Message -----
From: Bruce Plecan <nacelp at bright.net>
To: <diy_efi at esl.eng.ohio-state.edu>
Sent: Monday, May 17, 1999 9:32 PM
Subject: O2 Volts


> Per several off list letters I checked/doubled checked/thriple checked
> grounds and power for this bit of history.
>    I noted the following, using a 4 wire heated O2 sensor.  (General
Motors)
> With no power to heater, 0.0v.   For approximately 30secs 0.0, and then
> quickly rose to .1v, then then slowly climbed higher.
> When hot, there was a nominal voltage of .28v at the O2 sensor lead wire.
> Exposing this sensor to 97% O2 (Medical Grade O2, as tested this am) it
> drifted to .030.-.032v.
> Exposing this sensor to the Butane from a cigarette lighter that was unlit
> immediately responded with a display of .7v......
> Your O2 sensor is a HC Sensor...
> Bruce and the staff at CSH, HQ
>
Try feeding it co2 and see what it does - same as butane. The sensor is an
oxygen battery. If both electrodes are equal in oxygen you get 0 volts, more
or less (let's say .25 from your open air heated test). If one (the one
"outside" the exhaust is higher in O2 than the inner one, you get a higher
voltage.  If the inside is higher in O2 you get lower voltage. Use anything
other than oxygen - CO2, Argon, Nitrogen, Butane, or Propane.
This is the way the unit is designed - so this is how it SHOULD work.
When running at stoich, there is little O2 in the exhaust. The voltage
produced at this point is programmed into the ECU. If the voltage goes low,
the ECU richens the mixture. When the voltage goes high it leans the
mixture, and the ECU counts crossing points to determine if the system is
correcting properly.
>