Date:         Sun, 20 Oct 2002 08:34:59 -0700
Reply-To:     Tom Young <tomyoung1@ATTBI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Tom Young <tomyoung1@ATTBI.COM>
Subject:      Re: adjusting CO with O2 sensor
Comments: To: Pat Callaghan <patcal@CYBCON.COM>

From: "Pat Callaghan" <patcal@CYBCON.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, October 20, 2002 8:07 AM
Subject: adjusting CO with O2 sensor

>  I am going to check & maybe adjust my CO today & wanted to make sure I
> understood how to do this.  Warmed up, hook the + lead of the VOM to the
> single black wire from the O2 sensor, ground the - VOM lead.  The reading
> should be .5V.  Higher is richer & visa-versa.  Anything else to consider?


Just to expand on this...

I hook up my tachometer and disconnect the electronic idle control
stabilizer (N/A for water-cooled) since I find that adjustment to CO can
subtly affect idle and adjustment to idle can subtly affect CO.  After a
complete warm-up (e.g., a 20-minute or so freeway drive - you want the O2
sensor completely hot), kill the engine and hook up the VOM as described,
then restart.  The curve of the voltage output compared to air/fuel mixture
is *very steep* right around the correct CO so you really shouldn't see a
"steady" .5V; the VOM should rapidly  "jump" from "too low" (e.g., somewhere
around .3V -.5V) to "too high" (.6V - .7V) so what you're really looking for
is a pretty even split between the too low and too high numbers.

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Tom Young                        '81 Vanagon
Lafayette, CA 94549          '82 Westfalia
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