At 12:43 PM 6/12/2002, Vanagon man wrote:
>Hello, just replaced my O2 sensor with digitool hooked up.....prior to
>replacent, it was reading all over the place -1.7v to +2. volts.....

Something very off there.  The sensor itself doesn't generate outside the
range of 0 to roughly 1 volt.

>.....now with new one, it is reading around -.20 volts .............what
>the?

It's grounded -- either from the wire or the device itself is shorted/not
generating voltage.  It's got a little better ground than the ECU does, so
you're seeing a zero reading as -0.2 volts (the difference between the two
grounds).

>I have an exhaust gas analyzer, and cannot get the mixture to change on
>the afm ( i am doing it per Bentley)  When I give it throttle i get a
>plume of black smoke............the idle stabilizer IS functioning, vacuum
>is 15in at idle, and the fuel pressure reg is within spec.  I did a test
>to see if the fuel system maintained its pressure after cut off, and yes,
>so no leaky injectors.

The O2 sensor is telling the system it's lean, so the ECU is going
balls-out to richen it.  ECU doesn't have a sanity checker, it believes the
dirty lying O2 sensor.  Unplug the sensor -- if the Digitool reading goes
to about 0.5 v then it's sensor problem and your mixture should be
adjustable.  If Digitool stays at -.2 then you have a shorted wire (could
even be in digitool) or conceivably an ECU problem.

david

>My afm is 3 months old.
>
>Adam P

--
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"