Date:         Mon, 5 Apr 1999 21:11:44 -0500
Reply-To:     Darrell Boehler <midwesty@MIDWEST.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Darrell Boehler <midwesty@MIDWEST.NET>
Subject:      wet spastic oxygen sensor
Content-Type: text/plain; charset="iso-8859-1"

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Hi Volks,
    Today Chuck Hill and I got together and swapped some parts, it was a
pleasant spring  day everything going just right in Hannibal Mo. (home of
Mark Twain and busses by the arch 15) Then on the way home  I was traveling
in the rain with my 87 van when it lost power and would barely run.  David
Paterson had described this problem back in February. Luckily I was prepared
and had a digitool attached to the ecu and noted a very high  3.0 volt
reading on the oxygen sensor. I pulled over and disconnected the O2 sensor
from the ecu and attached a meter to the O2 sensor wire. It is kind of cool
being able to work and check out the wasserboxer engine from inside the van
during a down pour.  The van ran flawless the last 50 miles home in open
loop (O2 disconnected)
    I now had my meter attached to the O2 sensor and its readings would go
as high as 5.0 volts when I drove through water. As the sensor dried out the
reading would drop to a nominal 0.6 volts. The high readings would cause an
ecu to go way lean with the mixture if it were connected.  The O2 sensor on
this van is a bosch sensor for the vanagon with the special vanagon
connectors, no splices . The half circle splash guard was installed on this
sensor also.   David and several others have had problems stumbling in the
rain, and David said he had higher than normal readings on his  O2 sensor.
The fix seems to always be replace the o2 sensor.
    This van has never had  problems in the past in the rain. Somehow water
must get inside some O2 sensors as they get older.  I have no idea of the
age or miles on the O2 sensor, it could be the original 133k miles. Just
thinking it might possibly be a good idea to actually replace the O2 sensor
when the light come on instead of resetting the light and forget it.
Darrell