Date:         Tue, 18 Feb 1997 14:51:14 -0800
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         bayer@sybase.com (David Bayer)
Subject:      Re: disconnect 02 sensor

>| he asked if I had ever had to replace my 02 sensor. I said no and asked why
>| and he said his went bad and his mechanic (the same VW dealer I battled
>| with over the ECU) simply disconnected it. He said he didn't notice a
>| difference but was worried of the effects. He said the dealer said it was
>| only for emissions. I thought it also served a purposed on telling the ecu
>| how the engine was running, as in too rich, etc. Does anybody have any more
>| info?

	The O2 sensor will correct for a rich mixture (when it is working),
an over rich mixture will dump very high levels of CO and HCs into one's
exhaust pipes. High CO and HCs will react in the catalytic converter to come
out as water and carbon dioxide and a lot of heat. If enough heat is produced,
the catalytic converter's cermic (I think it is cermic in most of them)
plates will melt or break free and the converter will be useless. One would
then have an expensive repair ($900 from the dealer, $250 for the same one
from a mechanic, $100 from other places though the quality was suspect by the
mechanic) and be spewing HCs and CO into the atomsphere, but only if the
car is running rich.... 

	Overall, the o2 sensor is the thing that corrects for small problems
that come about with age of the intake system (except I suppose a failure of
the injectors). It can compensate for a pretty large vaccumm leak as well as
a faulty fuel pressure regulator. Try inducing a vacuum leak by bending the
idle stablizer tube off its nipple slowly. I got a hole the size of a penny
before the engine quit...

dave