O2 Sensor Open/Close Loop

[tom cloud]

        [ snip ]

>  Now I was under the impression this was because of the O2 sensor       
>  temperature (and the temp effect on O2 sensor volts), not because of a     
>  different desired AFR.... The sensor is not very useful very far from 
>  stoich, so I don't think trying to stay in closed loop would buy you 
>  anything.

        [ snip s'more ]

I recently did some digging into O2 sensors, reading research and SAE
papers.  From what I saw, O2 sensors, though very non-linear, are
repeatable and do give meaningful results off stoich.  The argument
was made on this group that exhaust byproducts other than O2, CO2,
and H2O skewed the output making the reading off stoich meaningless.
The stuff I read did not address this.  It did say that, off stoich,
the temp of the sensor changed the reading (i.e. calibration), so
it would not be accurate unless the temp of the sensor were factored
into the measurement.  Now, Todd K. says that he regularly uses the
EGO to help him tune his vehicles (that is what you said, isn't it,
Todd?), and I faithfully watch the digital readout from mine when
I tune my Bronco -- but I'm by no means an authority.  I just play,
but it seems to me to give "useful" readings off stoich.  In other
words, I feel that I can set my engine to give an EGO reading of
about .8 volts or so for power and maybe .1 to .2 for economy.

Flame on.


Tom Cloud <cloud at peaches.ph.utexas.edu>