Date:         Wed, 8 Sep 2004 16:08:01 -0700
Reply-To:     Craig Oda <craigoda@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Craig Oda <craigoda@GMAIL.COM>
Subject:      Re: Do I need a HEATED O2 sensor?
Comments: To: Tom Young <tomyoung1@comcast.net>
In-Reply-To:  <004301c49549$95ddaa60$1302a8c0@comcast.net>
Content-Type: text/plain; charset=US-ASCII

Tom,
you have my sympathies about failing CA SMOG.  My last SMOG adventure
took me to 2 different VW specialty mechanics, 2 trips to a FLAP, 3
trips to the SMOG tester and a half-dozen parts from VolksCafe.  The
main problem was that no one could identify the source of the problem.
 My cost was about $500 and there is no help from the gov in my case.

I just took my '90 Miata to a test-only SMOG center and it passed on
the first attempt.  The Miata always passes.  The guy at the SMOG
center in Mountain View, CA said that VWs often fail.

CA emissions now require dyno testing, NOX, HC, and CO.  The NOX is
new this year.

I have a Bosch Fuel Injection book at it appears that the Cat will
work only at near stoichiometric level, meaning the exhaust should
neither be too rich or too lean.  Prior to the NOX testing, you could
set the fuel-air mixture lean to burn the HC and CO.  But now, too
lean will produce NOX.

I've never tried this, but the site smogtips.com says that it might help.

http://www.blueskycleanair.com


What I think:
  - O2 sensor must be hot, but usually gets to proper operating temp
in under 2 minutes
  - cat must be hot to eat the pollutants.  Drive 20 minutes on the
freeway and idle your van while you're waiting for the testing
  - a new cat might help
   - changing oil might help

Good luck.

Regards,
Craig


On Tue, 7 Sep 2004 19:14:33 -0700, Tom Young <tomyoung1@comcast.net> wrote:
> Hi all:
>
> For many years I've been using the O2 sensor in my California Vanagon to
> adjust the basic air/fuel mixture; that technique has worked fine.
>
> When I rebuilt my Federal Westfalia (no O2 sensor) I installed a
> water-cooled catalytic converter in the exhaust.  Since the water-cooled
> converter has the O2 sensor bung I figured I could install an O2 sensor here
> to adjust air/fuel mix.
>
> The first time I tried it I was getting readings so low (indicating "too
> lean") that I couldn't believe it; the van was running well and screwing the
> adjustment screw all the way in basically had no effect on the readings.
> Since I was using an new O2 sensor the only thing I could think of was that
> the O2 sensor wasn't getting hot enough as the catalytic converter has a
> much larger diameter than the crossover pipe, thereby cooling the mixture.
>
> Accordingly, I installed an 18mm spark plug "anti-fouling" device in the
> exhaust in the crossover pipe.  The only thing is, since the anti-fouling
> device is quite a bit longer than a standard O2 sensor bung (couldn't seem
> to find one locally) the O2 sensor's tip is not fully in the crossover pipe.
>
> Again, the readings I was getting from the O2 sensor (new sensor, remember)
> were extremely low.  Since I just failed my Smog today (too-high HC,
> too-high CO) I know these readings aren't correct.  Again, I'm *guessing*
> that the problem is that the O2 sensor isn't getting hot enough, since the
> tip is not fully in the flow of the exhaust.
>
> So, I'm thinking I should buy and install a *heated* O2 sensor; if my
> problem is that the single-wire sensor isn't getting hot enough, that should
> work, right?
>
> Or am I missing something else here?
>
> TIA.
> ---------------------------------------------------------------
> Tom Young                       '81 Vanagon
> Lafayette, CA 94549         '82 Westfalia
> ---------------------------------------------------------------
>