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Re: O2 sensor (again)


     To: rich@pony.cis.smu.edu
   From: TACE96A
Subject: RE: O2 SENSOR (AGAIN)
   Date: 10/01/94 11:17 AM

        Bently IS weak on the oxs aproach because they reflect VW/A's
method of studying the Bosch system.  They tend to say 'try this, measure
that, if it isn't right try a known good component'.  Bosch (I havn't
attended their school but I sent one of my techs about a year ago) says
'understand the system, measure what is happening, and think like the

        The 'right' voltage is somewhere in the middle of the .1-.9V range
and with VW/A should only CONFIRM your mixture setting.  This setting is
done on the duty valve systems with a duty valve measurement taken with a
dwell or % reading, on the differential pressure regulator systems w/ a
milliamp reading at the dpr, and on the digifant systems w/ a gas analyzer
and tach.

        Volvo uses something called an integrator(?) voltage based on the
oxs reading on some of their cars.  Using a high impedence analogue volt
meter or a Fluke meter w/ the bar scale that shows you the range of
fluctuation of the voltage, Volvo wants a mixture adjustment where the
reading flips back & forth rapidly from .1V to .9V.  I'm unclear as to
whether this is a signal directly from tha oxs or if it's been processed by
the computer.

        Finally...to some degree this Volvo type rapidly fluctuating
reading can be obtained at the disconnected oxs wire on your VW/A system
and it should average near .5V.  A healthy sensor is always a plus because
they go slower & slower as they get older.

        Hope this isn't too boring, garbled, or inaccurate.

        BTW I didn't stamp, index or make this brief because I know how you
feel about these things.

                        ned bennett