Date:         Sun, 3 Aug 2008 17:37:36 -0700
Reply-To:     Mike Elliott <camping.elliott@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mike Elliott <camping.elliott@GMAIL.COM>
Subject:      Re: Heh -- I'm such a ninnyhammer
Comments: To: David Beierl <dbeierl@ATTGLOBAL.NET>
In-Reply-To:  <20080804001759.JJHL22786.eastrmmtao102.cox.net@eastrmimpo02.cox.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

M-kay, then what I might want to do is tune the engine w/ the O2 sensor
disconnected, yes/no?

For you guys that work on 1.9L Digijet engines -- what are the "knobs" I
use for the tuning? Timing is one, what else we got?

Or, to put this another way: what might I tell the shop to do w/r/t this?

Hey shop:

1. Disconnect O2 sensor . . . then
2. What?

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR



On 8/3/2008 5:17 PM David Beierl wrote:

> At 07:32 PM 8/3/2008 -0400, Allan Streib wrote:
>> Wait a minute -- so you are saying that in theory if a US spec Vanagon
>> has had the cat removed and is running a straight pipe that it does
>> not need an O2 sensor at all?
>
> Not theory.  O2 sensor is strictly emissions-related and enforces a
> very narrow range of mixture oscillating back and forth across
> stoich, which is what the three-way (nitrogen oxides, carbon
> monoxide, hydrocarbons --> nitrogen, CO2, water) CAT requires.  It
> prevents tuning the motor for either max economy (leaner) or max
> power (richer).
>
> As a *side-effect* it will compensate for other difficulties that
> affect the mixture equally across all four cylinders -- thus making
> them  impossible to diagnose without disconnecting the sensor.  As a
> different side effect, if one cylinder is misfiring or there's an
> exhaust leak upstream of the sensor it will drive the mixture way
> rich trying to get rid of the excess oxygen.
>
>
> --
> David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
> '84 Westy "Dutiful Passage," '85 GL "Poor Relation"
>