Date:         Fri, 29 Aug 2008 20:43:46 -0400
Reply-To:     pickle vanagon <greenvanagon@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         pickle vanagon <greenvanagon@GMAIL.COM>
Subject:      Re: When the O2 sensor cools down...
Comments: To: Jim Akiba <syncrolist@bostig.com>
In-Reply-To:  <ac1f198b0808291634q40605627l103732fab2259d3b@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Usually during engine braking it shows 0 volts for me.  Once the sensor has
cooled, it needle starts to drift up towards center (.5 volts).  It then
stays around .5 volts no matter what your doing until the sensor warms up
again.

This brings up something else I was wondering: does engine braking work when
the ECU is not in closed loop mode (for example at startup?)

-Wes

On Fri, Aug 29, 2008 at 7:34 PM, Jim Akiba <syncrolist@bostig.com> wrote:

> what does to voltage go to? does it drop way off?  During engine
> braking it should be quite lean which should show as low voltage on
> the narrowband o2
>
> Jim Akiba
>
> On Fri, Aug 29, 2008 at 6:59 PM, pickle vanagon <greenvanagon@gmail.com>
> wrote:
> > ...what happens?
> >
> > I rigged up a air/fuel mixture meter (just a voltmeter coming off the O2
> > sensor) a few months back.  On our recent trip across the country, we
> > obviously spent some time driving in hillier country than we usually do,
> and
> > I noticed something funny.  While engine braking down a long hill, all
> the
> > clear air coming through the exhaust system, while obviously hot, is
> > apparently not quite as hot as the sensor needs to be, so that it will
> > eventually cool down to the point where it no longer provides good output
> > and behaves like it does right after startup.  After driving for a
> little,
> > it warms up again and output is normal.
> >
> > I'm wondering what the ECU does during this stage.  Does it know to start
> > ignoring the oxygen sensor if it thinks its output doesn't make sense?
>  Or
> > does it just keep chugging along, thinking everything is peachy, and
> > consequently send too much or too little fuel as the oxygen sensor fails
> to
> > react dramatically enough to the changes in ratios of the exhaust gasses?
> >
> > -Wes
> > 1.9l westy
> >
>