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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?
Comments: To: laurence@alanasmith.com
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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