Date:         Tue, 31 Aug 2004 23:52:50 -0700
Reply-To:     Craig Oda <craigoda@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Craig Oda <craigoda@GMAIL.COM>
Subject:      O2 sensor problems
Content-Type: text/plain; charset=US-ASCII

Ever since I got my transmission back in, the van is running great.
I'm driving the old beast to work every day, taken it to Linda Mar
beach and to the SF zoo.

The engine idles fine and hasn't died yet.  Transmission fluid (AT) is
stable, no apparent leaks.

I've got a couple of issues with the van that I want to solve
eventually and I'm hoping some list members can help me out.  Due to
lack of knowledge on my part, I often make the van run worse when I
try to fix a problem with my 1.9L waterboxer with Digijet FI.

The van is running rich.  It doesn't affect drivability, but I can
smell the unburnt gas from the exhaust.  The fuel air mixture screw on
the Air Flow Meter is all the way out, counter clockwise.  In a
previous attempts to adjust the fuel air mxture, I messed around with
the spring inside of the AFM and I can't get it back to the original
setting.  (I didn't mark it.  :-(.  To lean out the mixture, should I
tighten the spring or loosen it?

In addition to running rich, I have weird behavior when the O2 sensor
is connected.  If I disconnect the sensor, the van runs fine.  So, I
disconnect the sensor when I want to make sure I get to work or to the
park.  I'm on O2 sensor number 3.  It's a brand new sensor with less
than 5 miles on it.

When I press the throttle after a full stop at a light, the van will
sometimes not accelerate for about 5 seconds.  Seems like a heck of a
long time when cars are backed up behind me.  If I keep the
accelerator floored, the van will eventually start to move.  This
problem only occurs when the O2 sensor is connected to the ECU.  When
I disconnect the O2 sensor from the ECU, the problem disappears.  I've
run the van over 1000 miles since I had the problem with the old O2
sensor sooting up.  I think that I've cleared the soot from the
exhaust system.

I have a voltmeter hooked up to the O2 sensor with the display for the
meter mounted on my dash.  When driving, the volts will sometimes drop
down to zero, indicating either a super lean mixture or something
funky going on with my O2 sensor.  When the engine loses power, the
voltmeter is saying that the fuel/air is super lean.

Under normal driving, the voltmeter says that the engine is running rich.

There are some other minor problems with the van, but I'm trying to
trace the source of this problem first.

Thanks.

-- Craig