O2 sensor is actually a temperature sensor???

[Greg Hermann]

>>
>>I guess nitpicking isn't the best way to make my first post, oh well, I'm
>>not like this all the time. =)
>
>Not if the nits are possibly important. I'd like to hear more about the
>history of these variations that were tried and then seemed to die out,
>only to resurface way down the road, when suddenly one of their
>properties becomes of greater interest again. The recent emergence of
>the 4-wire WBO2 sensor (a "Zirc" sensor, BTW, and NOT the same as a
>temperature-compensated conventional HEGO, like the Bosch LSM-11) is
>also a case in point; their electrics is more complicated even than the
>O2-pump style 5-wire sensors, because they have to be run in "phases"
>relating to the amount they are warmed up or "activated" (to use the
>parlance of their vernacular), BUT because they can be made to detect
>stoich zero-crossings at an earlier time than the 5-wire type, they seem
>to be taking over as a sensor that has the combination of eventually
>being useable for some actual AFR measurement once high temps are
>reached AND can also help out the OEM vehicle mfg. with his cold-start &
>warmup emissions requirements. Because the sooner the O2 sensor can be
>used to at least find stoich, the sooner the ECU can be placed in
>closed-loop. Soooo, altho these 4-wire WBO2 sensors aren't apparently as
>accurate for AFR measurement purposes, they represent a better tradeoff
>for smog. Hence Honda themselves switched from the NTK 5-wire sensor, to
>a Denso 4-wire WBO2, in the '96 and later models of the Civic HX.
>They're about the same price as repair parts, so it wasn't likely an
>"economy" move, but rather a shift in focus of priorities, and this
>4-wire WB technology became an overall better choice for them.
>
>Just some thots on a fascinating subject, IMHO.
>
OK--what really came first--Westinghouse patents for use on gas turbines,
or patents for stack gas analysis on stationary boilers? This stuff has
been around for damn near 50 years.

Greg


----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org