O2 sensor question - how it works

[Garfield Willis]

On Sat, 25 Mar 100 17:54:19 +0800 (WST), Bernd Felsche
<bernie at perth.dialix.com.au> wrote:

>Why can't the ECU do a "free-air" calibration on over-run?
>(Say after 50 revs of "purge".) Just curious.

It's surprising how long it takes to actually GET to free-air
concentrations of O2. I don't think a span of time as brief as 50 revs
is enough to clean the exhaust; it's a fairly big "gas capacitor" if you
will. But you're right; shutdown is about the only possible time
available. Methinks it's the old story of the fixed cal resistor trim
being "good enough for who it's for". Best engineering choice given the
alternatives.

>I've found the later SAE papers to be less-generous with technical
>details. Could just be the non-random sample I've chosen.

Yup, it's just like patents. Depends entirely on the authors. Win some
lose most.

Gar


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