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Re: Air-fuel mixture gauge

To: Douglas Braun & Nadia Papakonstantinou <dougbert@rcn.com>
Subject: Re: Air-fuel mixture gauge
From: Barry Schwartz <bschwart@pacbell.net>
Date: Tue, 18 May 1999 08:40:07 -0700
>I am just a little confused about the "cycling" thing.
>Assuming that the engine is operating at a steady
>condition, does the voltage fluctuate?  Is
>this a property of the sensor itself, or is it because
>the exhaust gas stream is not a uniform mixture?
****************************************
Yes the voltage does fluctuate, and its due to the nature of the sensor.
Given a steady fuel/air mixture, for an arbitrary example say a 12:1 as a
constant, then you would get a "steady" voltage of around .7 volts cycling
(on/off) at around 7 times a second (using the illustration in my previous
post)  For practical purposes, most digital meters will dampen out these
fluctuation and you will get a steady voltage reading.  It is however, not
truly steady state - that is the voltage your measuring is not the *actual*
voltage of the unit, and you really need to an oscilloscope to see the true
voltage- I just thought you might like to know what's actually going on
with these sensors, so as to have a little better understanding of just
what they actually do -

Barry Schwartz (San Diego) bschwart@pacbell.net


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