EGO Sensors and linearity

[Frank F Parker]

On 20 Aug 1996, Alexander M. Lichstein wrote:

> If you look at the math involved with understanding the output of an O2 sensor,
> I can't BELIEVE that you can make a claim that you will be able to determine an
> A/F from the output (even with Temp.)  You would need to know the proportions
> of exhaust gas components at every temperature (including SPECIES of SOx, NOx
> etc.) in order to make that claim.  I am tired of reading this garbage.  Anyone
> have any science to back themselves up???
> 
> - Z 
Well this is one of those cases where you are trying to overanalyze the
situation. I agree it is hard to make any sort of accurate>calculation
of a/f from a standard HEGO although a lot of people are able to monitor
changes from mods, compare to trap times and note for example that a 
change from .82 to .84 volts in that particular car and temps correspond
to a too rich situation and trap times fall. It is repeatable until
sensor ages to a certain point.
Bosch sells the LA-2 $8000 a/f meter that reads accurate a/f ratios using
a modified HEGO, NOT a UEGO. THis sensor is modified for reduced
flows and constant temp. The box reads voltage, compensates for temp
and reads out a/f. Read about it in "Automotive Electronics Handbook by
Ronald Jergens, editor. Section on O2 sensors by Bosch engineer.
I and another user on working on homebrew box to be used with the Bosch
sensor which is cheap that will read out a/f and be affordable.
It may not be perfect but it works and is used everyday in labs all over
the world.

	Frank Parker
PS- I agree lot of talk I see showing simple voltage measurement to
read a/f is garbage by people that do not understand, but do not make
blanket observations, you might be suprised. I have Bosch curves from
LA-2 and it works!.

	fp