Date:         Sun, 8 Jul 2012 11:23:06 -0700
Reply-To:     neil n <musomuso@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         neil n <musomuso@GMAIL.COM>
Subject:      Re: At Idle: AFM Flap, CO Screw Relationship. Explanation Found
Comments: To: Dennis Haynes <d23haynes57@hotmail.com>
In-Reply-To:  <BAY152-ds31667CC0C2A1C6B96C06DA0EC0@phx.gbl>
Content-Type: text/plain; charset=ISO-8859-1

Would an analogue VOM be better for measuring voltage at O2 lead?

After a full tune up and installation of a new O2, cat, muffler, my
idle readings on emissions test were certainly within spec for a 1988
Vanagon

https://lh3.googleusercontent.com/-l33W52gqM2k/T6mr8PbdnRI/AAAAAAAAFv8/5rraW9Yry_Y/s1024/1988%2520Westy%2520Emissions%2520Test-pass%2521.jpg

Since the CO screw was fully seated, IF this was incorrect, the new O2
sensor certainly did as you suggest it should.

After passing emissions, I started testing and working on things like
the throttle valve switch, idle stabilization circuit and parts
(module was bad). At that point I discovered the CO screw was screwed
all the way in.

Neil.

On Sun, Jul 8, 2012 at 5:57 AM, Dennis Haynes <d23haynes57@hotmail.com> wrote:

> With the sensor disconnected from the engine the mixture screw should affect
> the O2 sensor reading. You want to adjust for about .5 volt. This is usually
> as little as 1-2 turns open.  Even fully closed the O2 sensor should
> compensate. On the 1.9L engines incorrect setting can add to the factors
> that cause that idle surging.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> neil n
> Sent: Sunday, July 08, 2012 2:59 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: At Idle: AFM Flap, CO Screw Relationship. Explanation Found


> As per your other post, I measured the voltage output of the O2 sensor
> (after disconnecting, engine off) while turning the CO screw. I saw higher
> voltages ( ~ 0.8 ) and the output fluctuated some (maybe analogue VOM better
> for this purpose?) but in general, adjusting the CO screw affected the O2
> voltage output. Maybe the sensor had cooled down prior to test (had engine
> up to temp, then it sat for about 10
> minutes)

........


> Not sure why a PO set the CO screw all the way in (bypass closed off).
> Compensate for a vacuum leak? Worn throttle body valve?

--
Neil n

65 kb image Myford Ready For Assembly  http://tinyurl.com/64sx4rp

'88 Slate Blue Westy to be named.

'81 VanaJetta 2.0 "Jaco"  http://tubaneil.googlepages.com/

Vanagon VAG Gas I4/VR Swap Google Group:

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