Ox sender actual function

[Roger Heflin]

>From what I read on it (that paper), their methodology seemed correct
and if they got the results listed then their conclusion seems pretty
correct.  It would also explain why no one does misfire detection
using O2 sensors.  And really from the EPA's point of view it does not
matter exactly what they detect so long as they detect something that
can be used go generally tune the engine.  

On Wed, 25 Nov 1998, Mark Wilcutts wrote:

> Maybe I shouldn't have posted only the first two pages.  With only part of
> the paper, you don't get the whole picture.  The paper is actually quite
> well written and makes it's points in a convincing fashion. They just
> don't START with the assumption that the sensor senses oxygen. This
> approach was needed because they were getting conflicting results from
> their misfire tests. Comments below. 
> 
> On Tue, 24 Nov 1998, Orin Eman wrote:
> 
> > The first paper sets my BS detector off... as in the writers were
> > completely clueless or they had some political agenda...
> 
> Do tell, what would that agenda be? If anything, they were annoyed because
> they had been told by the manufacturers "this sensor senses oxygen", and
> they found in their misfire tests that it didn't, as many of us have been
> told, and are understandably annoyed. (For us it means we can't build our
> own AFR sensor!)

On top of that they gave some pretty detailed graphs of what they
found the sensor detection at what temp of sensor, and how linear it
was.    If they did not make the graphs up they did alot of work to
get that detained of data.

 > 
> I don't buy into conspiracy theories or "the gummint is just a big buncha
> idiots". 

I generally count sloppy science, but I really could not see anything
sloppy in it.   Anyone have a manufactures data sheet on an O2 sensor?
I have heard certain manufacturers mechanics (VW) call an O2 sensor,
a HC sensor,  I expect all of the manufactures know and just call it
an O2 sensor because it is simpler to explain.

 > 
> > <<However, very rich A/F ratios did not result in hIgh port sensor
> > voltages when there was no ignition.>>
> > 
> > No surprise here either.  No ignition means 20% oxygen, same as
> > on the other side of the sensor - so no voltage produced.
> > The sensor really measures 'lack of oxygen' in the exhaust.
> 
> Ah, but where the surprise comes in is that at higher misfire rates, the
> sensor indicates rich!
>
The other thing that bothers me about it being an O2 sensor, is that
if it was having a plug wire should make the O2 sensor on that side
measure really odd, but I have not ever seen that, which makes me
believe that maybe it is sensing something else.
 
> > <<These results indIcated that some physical property of the unburned
> > air/fuel mlxtures, such as the relatively high  concentrations of
> > hydrocarbons. or the absence of other types of reducing agents,
> > such as hydrogen and carbon monoxide, inhibited the voltage generating
> > capabilities of the sensors.  >>
> > 
> > Huh???  No mention of the simple fact that with no ignition, there
> > is lots of _oxygen_ there...  Why no mention?  Why are they avoiding
> > discussing what is generally thought to cause the low sensor voltage?
> 
> Beacuse higher misfire, e.g. more oxygen, and you get a rich reading...
> they are taking a scientific approach - see how something behaves, then
> match theories with it.
> 
> 
I think their other conclusion was that it was an O2 sensor, but only
at temps that no exhaust system would ever see, so they wanted to see
what it acted like at what would be normal operating temps, and their
conclusion was that it sensed HC and not O2.

I would like to see more papers on this.  I will have to look on a CD
I have from another one of the professional societies that may have
done similar work.
			Roger