Ox sender actual function

[Bill the arcstarter]

Mark Wilcutts wrote:
>Only when oxygen ions diffuse through the ZrO2 ceramic substrate do you
>get a voltage on the sensor, perhaps the testers were misinterpreting 
the
>results...  The voltage you get from the sensor is related to exhaust
>oxygen concentration by
>
>V = kT/2e ln(P(O2)_a/P(O2)_e)

Interesting.  I've been poking around the archives looking up O2 sensor 
stuff.  Seems like well informed people have presented contrasting 
claims as to what those sensors actually sense.  I'm still not convinced 
anyone quite knows the answer...

Here's a message I posted to the www.se-r.net list a few months ago (the 
se-r is Nissan's sr20de / sr20det platform).  It describes my own 
experiments on O2 sensors (which I still don't believe sense O2 due to 
my propane / argon experiment...):

>Drivers,
> I spent some time playing with a used (but not dead) Bosch O2 sensor.  
I'd 
>removed this sensor from my car at 75Kmi due to old age and routine 
maintenance...
>
>The sensor heater requires 12 volts, 1 amp from the red to black wire.
>
>The output signal is measured (voltage) from the sensor case to the 
>white wire.
>
>The sensor takes a LONG time to heat up - a good 3-4 minutes is 
required 
>before the output signal represents actual conditions.  Heatup time 
>would be shorter if it were installed in an exhaust system of course!  
>Perhaps this explains why the ECU runs open-loop for so long...
>
>I measured voltages <0.10 with the sensor in free air, and >0.60 if I 
>blow pure propane (burned or unburned) over the end.
>
>The strange thing is that immersing the sensor end in 100% argon did 
NOT 
>produce a lean ( >0.5) reading but was undistinguishable from the 
>free-air reading.  This leads me to believe that these sensors are not 
>actually O2 sensors, but perhaps hydrocarbon sensors...  Comments 
>anyone?
>
>I'm told that O2 sensors won't read properly under WOT conditions.  Can 
>anyone explain why this is??

Later.  Let the O2 sensor debate rage on!

-Bill the arcstarter
Starting arcs in Cinci, OH
http://www.geocities.com/CapeCanaveral/Hangar/6160


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