O2 sensors / bargraphs.

[Dale Ulan]

> 
> 
> Is there a way to possibly use an EGT reading to compensate for the temp?
> 
> > Also, since these displays show the _VOLTAGE_, and the voltage is
> dependant on the gas composition AND temperature, does this mean that
> the temperature variation is going to make the reading too in-accurate (eg
> more than 10% incorrect)...

Not only does the reading vary with temperature, but *also* with age...
believe it or not. Also, the manufacturer of the cell can affect the
output characteristics: the vertical line in the curve remains the same,
but the output voltages on either side vary. I've actually seen a case
where a GM sensor worked fine, but putting a Ford sensor on confused
the computer in a major way.

here's an article... it's good reading material:

SAE paper 920289, 'Operating Characteristics of Zirconia Galvanic
Cells (Lambda Sensors) in Automotive Closed-Loop Emission Control
Systems, by Bozek, Evans, Tyree, and Zerafa of the EPA.

-dale