Bob,
You and the vanagon people on this list are awesome.  I think that my
2nd O2 sensor got clogged up due to all that soot in the exhaust.
After driving for a while without the O2 sensor connected, I bought a
new one from Kragen.  Cheap, only $30, low cost especially considering
the gas I burned through this weekend.

I did a test drive tonight and I got over 18 mpg, up from 5 mpg this
weekend.  Yay!!!

I also cleaned all the grounds on my cylinder head and added a new
ground cable from the coil bracket bolt to the cylinder head on the
driver's side.  I changed the oil.  It was black.

Should I run a bottle of fuel-injection cleaner through the gas system
to help that soot get out?

Thanks to everyone that helped me with this problem.

I was getting anxious because I am planning to take the family to the
lake this weekend in the van, about a 300 mile drive each way.

On Tue, 13 Jul 2004 22:30:18 -0400, ROBERT DONALDS <donalds1@verizon.net> wrote:
> Craig
> once the exhaust is sooted up you need disconnect the oxy sensor and drive
> the van or it just fouls out one sensor o2 after another. You said the van
> runs fine without the sensor connected. So with this thought in mind you
> dont need the o2 sensor to drive the van. give the exhaust a chance to clear
> out say 200 miles and reconnect the o2 sensor
> in the mean time change the oil its full of fuel and keep a close eye on the
> milage if it does not go way up you still have a problem.
> let me know
>
> Bob Donalds
> Boston Engine
>
>
>
> ----- Original Message -----
> From: "Craig Oda" <craigoda@GMAIL.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Tuesday, July 13, 2004 1:38 PM
> Subject: Running rich, O2 sensor says lean, exhaust leak?
>
> > This past weekend I averaged 5 mpg and there was a lot of unburned
> > fuel coming out of the exhaust.  I've got a voltmeter hooked up to the
> > O2 sensor and the voltage was measuring consistently lean, despite the
> > obvious signs of the engine running rich, such as gas smell and black
> > smoke, not to mention high fuel consumption.  There  was also
> > drivability problems, including loss of power and some surging.
> >
> > This morning I disconnected the O2 sensor before I went to work.  The
> > engine drove much better.  I'm now thinking that there is an exhaust
> > leak that is causing air to leak into the system and causing the O2
> > sensor to read the air-fuel mixture incorrectly.  Although this seems
> > counter-intuitive since the exhaust is presumably under pressure in
> > the system and pushing out of the back, I've heard of a process called
> > exhaust scavenging where an exhaust pulse pulls exhaust through the
> > system.  Each high pressure exhaust pulse travelling through the
> > system results in a bit of pull
> >
> > I obviously want to reconnect my O2 sensor.  Before I take off the
> > exhaust system and change the exhaust gaskets, is there anything else
> > I can check?
> >
> > Stuff I've done in the past week:
> >   - changed O2 sensor
> >   - changed fuel pressure regulator, fuel pump, fuel filter
> >   - took apart entire air intake system, changed the air intake
> > distributor box, and most rubber hoses.
> >    - changed temp sensor II
> >    - adjusted valves
> >    - looked for exhaust leaks under the van, but couldn't find any
> > obvious ones.  I haven't taken the system off for inspection.... yet.
> >
> > Also, my exhaust system has a dent in it right after the O2 sensor.
> > Could this be causing a problem with the exhaust flow?
> >
> > I have a spare exhaust system and a newish auxiliary air regulator
> > that I can swap in for a test.  Right now, I think it is air leaks
> > into the system or maybe that dent.
> >
> > Any advice before I crawl around under the van and get dirt falling in
> > my face, hair and eyes?
> >
> > -- Craig
> >
>
>