Path: utzoo!attcan!utgpu!watmath!iuvax!mailrus!tut.cis.ohio-state.edu!attctc!robp
From: robp@attctc.Dallas.TX.US (Robert Parnell)
Newsgroups: sci.electronics
Subject: Oxygen Sensor Info Needed
Message-ID: <9187@attctc.Dallas.TX.US>
Date: 31 Aug 89 07:29:24 GMT
Reply-To: robp@attctc.Dallas.TX.US (Robert Parnell)
Organization: The Unix(R) Connection BBS, Dallas, Tx
Lines: 31


Recently I saw an ad for an oxygen sensor that is used to adjust the air/fuel 
mixture for an internal combustion engine.  It had a sensor that mounted in
the exhaust manifold, and a small box with an LED bar graph display that 
mounted in the driving compartment.  Mid scale on the display indicates proper
fuel/air ratio, above or below indicates too rich or too lean a mixture.  The
idea behind the device is that with a lean mixture more oxygen will remain in 
the exhaust gases than with a rich mixture.

The sensor that mounts in the exhaust system is a standard automotive part
used in electronic fuel injection systems, and it's my guess that the small
box is nothing more than an ohm or volt meter with bar graph display.

I would like to use this method to adjust the carburetors on my motorcycle,
but with the commercial system selling for just over $200, I would like to
roll my own.  The sensor sells for around $40 at the local auto parts store,
and I already own a VOM.

What I need to know is the electrical characteristics of the oxygen sensor.
What's the resistance or voltage output of the sensor when the fuel/air
mixture is correct (which I believe is 15 grams of air to 1 gram of fuel)?

The commercial oxygen sensor kit comes with a sensor, but if it is to be
installed in a car with fuel injection that already has a sensor installed, 
the existing sensor can be used instead of the sensor supplied with the kit,
which leads me to believe that the electrical characteristics of different
oxygen sensors are the same, regardless of manufacturer.


Robert Parnell
robp@attctc