Barry Schwartz wrote:
> I?m considering setting up a fuel/air ratio meter using a digital
> voltmeter (0-1V), and a Bosch oxygen sensor. How does one connect the
> sensor up. Is one lead just connected to a switched, positive side of
> the battery, and the reading taken from the center lead and a ground?
If it's a standard "one wire" unheated sensor, just read the voltage
off the wire, the unit grounds itself in the exhaust manifold.
> Or is some additional wiring required? - I haven?t got the sensor yet,
> but plan on buying the universal, unheated sensor. I can?t see spending
> $150 for a 0-1V led readout just to test fuel/air readings, and once set
> have it sit on the shelf! Any of you wizards out there have any ideas?
It's VERY difficult to read with a digital multimeter. The actual
range of the unit is very nonlinear, the computer uses the number of
"lambda crossings" to determine if the unit is roughly centered.
It's confusing, but instead of the unit outputting 0.5V at correct,
it will oscillate from 0.2V to 0.8V when correct, spending roughly
half the time at each. Too rich or too lean and it will spend much
more time at one end and cross the middle less often.
With a fast sampling meter you just get unreadable noise, with
a slow sampling meter you get somewhat random samplings that are
hard to correlate.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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