Nolan,
I'm pleased that you find this device useful. And yes,
there is a slope, with rounded edges.
My point though was that despite the misleading
multi-LED readouts, these devices are *not* wideband
AFR meters.
Since they depend upon the transition characteristics
of the common zirconium O2 sensor, they can basically
indicate lean/rich. This limited info can be useful,
but there are a few caveats.
The transition threshold, and the shape and position
of the knees you mentioned, varies for each sensor
with temperature, manufacturing lot, manufacturer,
age, and condition (clean or 'dirty').
In an EFI system running closed loop, the ECU varies
the mixture strength continuously, looking for
transitions in the O2 voltage (crossings). When the
sensor indicates 'lean', the ECU richens the mixture
until it goes 'rich', the ECU leans the mixture until
it goes 'lean', etc...
So, on an EFI car in closed loop, one of these meters
will indicate in the yellow 'stoic' zone, as the O2
voltage transitions vary within this range.
Check out this link to see an O-scope display of the
voltage signal from an O2 sensor running on a closed
loop ECU system:
http://www.cnnw.net/~fourty/uses.html
BTW, anyone seriously interested in more details about
EFI construction, tuning, and operation can email me
offlist for links to several lists devoted to this
subject.
Thanks
Carter Shore
--- Nolan Penney <npenney@mde.state.md.us> wrote:
>
> >They function like an on-off switch in the presence
> > of Oxygen. NO oxy, off, ANY oxy, on.
>
>
http://www.conservatory.com/vw/manuals_nyx/Images/FeulInjection/L-JetronicLambda/LJETL-18.GIF
> That's really not true. While the slope is quite
> steep at stochiometric conditions, there is a slope,
> with
> a radiused curve. The above link shows a typical
> profile of this.
__________________________________________________
Yahoo! Mail - Free email you can access from anywhere!
|
