O2 sensor question - how it works

[Bernd Felsche]

Garfield Willis writes:

>On Fri, 24 Mar 2000 22:46:02 -0600, "Brian Franchuk" <franchuk at mm.com>
>wrote:

>>For a good explanation of how the LAF oxygen sensor works see 
>>the following web page:
>>	http://www.tech2tech.net/training/laf.htm

>Oh my, well, that's a noble attempt, and lots of basic things mentioned
>are correct, but there's a bunch of stuff that's also NOT correct in
>this discourse. Suffice it to say, the secret salsa recipe is safe, from
>anyone who thinks this is actually the way the sensor works from an
>operational standpoint. He's got the basic physics of the thing right,

[snip interesting stuff]

>factory-set "parallel trim value" in the ECU circuitry (which doesn't
>have the luxury of doing a free-air calibration like we proformance
>users can), and as such, varys widely for only slight (15% overall)
>changes in the sensor calibration itself. But there's nothing "typical"
>about the cal resistor value. It varys widely.

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

>do. :)  It's sorta close, but no cigar. A little help from the NTK SAE
>paper (#920234), and he could have avoided some of the more glaring
>mistakes.

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

-- 
Real Name: Bernd Felsche
    Email: nospam.bernie at perth.DIALix.com.au
     http://www.perth.dialix.com.au/~bernie - Private HP
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