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Re: Air/Fuel Gauge/Sensor Location

To: Spitfires@autox.team.net
Subject: Re: Air/Fuel Gauge/Sensor Location
From: "Nolan Penney" <npenney@mde.state.md.us>
Date: Wed, 06 Sep 2000 15:25:38 -0400
>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.

This slope allows a properly calibrated electrical device to indeed reflect the 
different excess air
ratios in a display.  I have seen them in use, and they do indeed do this.  The 
range of effective
sensitivity and display is restricted, but that is quite acceptable for most of 
us as we are not 
going into incombustable ranges.

The gauges have a wonderfull usefullness with carburetors for detecting and 
identifying
improper fuel mixtures at operating conditions other then idle.  Very helpfull 
in selecting
a needle profile with SU's, or altering emulsion tubes and such with more 
typical fixed
jet carburetors.  

Even with fuel injection though, the gauges still read quite well due to 
dampening
circuits wired into them.  Be it the led display type, or the analog needle 
unit.


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