Ken-

I know those gauges are exciting, but do your fellow North Carolinians a favor, and continue to watch the road...;)

G. Matthew Bulley
Bulley-Hewlett
Corporate Communications Counselors
www.bulley-hewlett.com
Cary, NC USA
888.468.4880 tollfree
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-----Original Message-----
From:   kenneth d lewis [SMTP:kdlewis@JUNO.COM]
Sent:   Monday, November 29, 1999 8:08 PM
To:     vanagon@GERRY.VANAGON.COM
Subject:        Re: How does the Oxy Sensor Work/ go bad?

Horace;

        The O2 sensor fine tunes the FI system to achieve stoichiometry.
A rich condition produces a voltage output from the sensor, about .9
volts. A lean detection results in no voltage. This cycle repeats itself
several times a second.
        My monitor has ten LEDs, each one represents 1/10th of the total
sensor output. This type of representation is called a moving dot
display. The sequential lighting of LEDs is analogous to an analog meter
movement.

Some O2 monitor observations from my truck:

1> When the engine is first started the Dot  "floats" in the middle of
it's range. This tells me the sensor is not grounded or otherwise
shorted.
2> As the engine/O2 sensor starts to warm the Dot creeps towards rich.
3> When the ECU switches to closed loop operation the Dot swings back and
forth rapidly.
4> At full throttle the Dot stays pegged in the rich zone.
5>When the idle position sensor is activated the system stays rich for a
few seconds then leans out for a few seconds.
6> An old O2 sensor caused the Dot to jitter and move lazily as opposed
to a new sensor which gave crisp and rapid Dot movement from one end to
the other.

 I am going to put together a batch of these soon. I am considering
adding a second similar gauge that monitors the charging system or
auxiliary battery (or all three). They should be relatively inexpensive.
Drive Safely & Good Luck
Ken Lewis<Kernersville,NC>