Date: Tue, 13 Jul 2004 14:15:58 -0700
Reply-To: Craig Oda <craigoda@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Craig Oda <craigoda@GMAIL.COM>
Subject: Re: Running rich, O2 sensor says lean, exhaust leak?
In-Reply-To: <NBBBLKPACPEEKLBIBDMMOEBNIHAA.laurence@alanasmith.com>
Content-Type: text/plain; charset=US-ASCII
Laurence,
thanks for the tip. This might be a source of problems. I do notice
that the ground wire is slightly corroded and worn out a bit. I
dropped the current engine in about a year and a half ago. At the
time, I cleaned the contacts. Maybe I need to do it again with a
fresh fat battery cable in there.
You think this is the primary ground I should clean first? I cleaned
the big fat one under the van about 2 years ago.
The thing that I don't understand is why the O2 sensor keeps telling
me (and the van's computer) that the exhaust is lean. Could this be
caused by a bad ground to the engine block?
I'm using a single wire O2 sensor. So, it's grounded to the exhaust
system. I was thinking about running a ground from the sensor to the
engine block. You think this would help?
Regards,
Craig
On Tue, 13 Jul 2004 14:08:34 -0400, Laurence Smith
<laurence@alanasmith.com> wrote:
> You did not mention cleaning the grounds, especially the one on the
> engine, driver's side head. If this ground is bad you get very rich
> symptoms.
>
> ----------------------------------------
> Laurence Smith
> Hamilton, Ontario, Canada
> 90 Westy / 90 Subie 2.2
> 87 GL / 91 Subie 2.2
> ----------------------------------------
>
>
>
>
> > -----Original Message-----
> > From: Vanagon Mailing List
> > [mailto:vanagon@GERRY.VANAGON.COM]On Behalf
> > Of Craig Oda
> > Sent: Tuesday, July 13, 2004 1:38 PM
> > To: vanagon@GERRY.VANAGON.COM
> > 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
> >
>
>
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