O2 voltz

Bill the arcstarter arcstarter at hotmail.com
Sun May 16 02:12:19 GMT 1999


Various people wrote:

>>  I had hooked the scope probe across the O2, and cold there was no 
>>output,
>>to be expected, but as it warmed up the output swung toward, .2v.  Just in
>>atmospheric conditions.  Ok, so then it should go way high in pure O2 
>>right,
>>nope went a little over .3, and stopped there.
>>  Did I need to load the sensor?.
>>  The heater doesn't go to a high enough temperature for the O2 to fully
>>swing high?.
>>  Does the engine side need to see a slight amount of pressure to 
>>reference
>>to?.
>
>Bad thing about O2 sensors is they aren't truly O2 sensors... they are HC 
>sensors. In pure O2, the sensor should keep a low voltage.  In an 
>environment rich with HC (IE propane, unburnt fuel etc) they should go .9-1 
>Volt.

I can confirm this.  My "O2" sensor could NOT distinguish between air and 
100% argon (from a TIG welder).  However it responded gloriously to a bit of 
raw propane from the plumber's torch...

(The O2 sensor was a 3-wire electrically heated Bosch unit)

There is indeed a great mystery here as there is obviously much more to the 
story than "They sense O2".  ('cause they don't!)

If anyone knows the whole story I'd love to hear it :)

-Bill


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