O2 sensor bias/ a/f curves

[Frank F Parker]

> Yes I do. In the Accel EMIC Training Manual (don't ask!) on page 1-5 , Fig
> 1.3B presents a graph of the output vs. lambda of whatever Bosch 3 wire
> sensor it is that Accel sells with their EFI kits. "Output voltage switches
> rapidly from 200--800 mv" at lambda =1 (14.7:1). Looking at the graph, the
> output is down to  100 mv by 15:1
> and up to 900 mv by 14.4:1. It is nearly a vertical line between 200 and
> 800 mv, at 14.7:1, as they claim. (The far rich and far lean ends of the
> curve are at 950 and 50 mv, respectively.) Basically, you are playing with
> yourself to try to use a standard O2 sensor to try to control anywhere but
> at 14.7:1 with this  shape output profile.

Greg is absolutely correct about this. All other curves showing anything
other than a slightly sloping on ea end Z shape are just not correct and
held over from published data by companies that made 10 led meters and
supplied a "curve." This has been gone over alot- more info in archvies.

> On the other hand, I also have voltage vs. lambda output curves for five
> different models of the NGK/NTK 5 wire, wide band O2 sensor controllera.
> With this puppy, you can control to any lambda ratio you want, and they
> show data indicating that it is quick enough to pick up a random misfire
> AFTER the CAT! Unfortunately, retail on one of these is $600 or so,
> including the control box. God knows where to get them at any kind of a
> discount, I don't---maybe one of you does???
> 
Here is the story on NTK sensors: NTK/NGK sold the air/fuel marketing
rights to Horiba here in Ann Arbor. They mark the price WAY UP for
even the cheapest model. If you are using for microproc control like
some latest DFI and the excellent FelPro, THEN you can get from NTK
directly if you SIGN a legal agreemeent. Price from a quote I got
are: Interface box-$400, Sensor-$600, harness-$60.

A number of vendors have thougt about builing a cheap NGK 5 wire 
a/f meter, BUT Horiba lawyers are very aggresive in protecting their
profit margins. It is pretty dumb. They could license to one of the
vendors and make money on that without really affecting their sales to
companies like Ford etc.

I have both Bosch LSM-11 sensder and interface as well as the NTK
and have run curves compared to std O2 sensor and what Greg says
is true. I have seen the hard numbers. 

This is not to say you can not use a std O2 to tune. You can. They
are very repeatable and in a known situation like the GN cars, and
without large changes, they have been pretty successful in tuning
to a particular voltage BUT it would not be the same voltage in
your car.

regards,

frank Parker
>