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Re: O2 sensor for your MG

To: Jurgen Hartwig <gt0003a@prism.gatech.edu>
Subject: Re: O2 sensor for your MG
From: Trevor Boicey <tboicey@brit.ca>
Date: Thu, 27 Aug 1998 23:15:13 -0400
Jurgen Hartwig wrote:
> 
> Hi all, I recently acquired plans to install an O2 sensor into my Porsche.
> I thought that since it is a universal technology, I thought you guys
> would be interested.  Next time you're driving down the highway, you can
> tell, in an instant, how you air/fuel mixture is doing,

  Well, you can, but not as well as you might wish.

  Unfortunately, the O2 sensor has a very narrow notch
of usable outputs. The commercial versions have a temptingly
useful range of LEDs ranging from "Lean" to "Rich" with
lots of good ones in between.

  Unfortunately, the output of the device doesn't
really work this way.

  More properly, the output of the device is best analyzed
by microprocessor, and the output is hard to "sanitize"
to where it's any use for a human. The output voltage
of the device is very highly varying, and swings
wildly and constantly from "lean" to "rich".

  The important value from the output is the properties
of the "zero crossings", which is the moment where the
sensor output is roughly in the middle of it's range. By
analysing the pattern of zero crossings and the ratios
of time spend below and time spend above the middle,
the computer can make a fueling decision.

  It's cheap to install, so give it a shot, but unfortunately
it isn't as nice as the cheap gadgetmakers would like.

  Lots more (and better recalled!) info at:

http://atlantis.austin.apple.com/people.pages/Jimbo/o2info.html

-- 
Trevor Boicey, Ottawa, Canada.
tboicey@brit.ca, ICQ #17432933
http://www.brit.ca/~tboicey/

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