Date:         Sat, 21 Sep 2002 23:42:11 -0500
Reply-To:     John Rodgers <j_rodgers@CHARTER.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Rodgers <j_rodgers@CHARTER.NET>
Subject:      Re: Measuring oxygen sensor output...bad air flow meter?
Comments: To: Jbclem <jbclem@EARTHLINK.NET>
Content-Type: text/plain; charset=us-ascii

From what I have read in my study of the fuel injection system and how
the ECU utilizes O2 input to regulate it, the O2 sensor only comes into
it's own when the 02 heater is working. Then, the O2 sensor will read a
positive voltage one second, a negative voltage the next second. If you
had it hooked to an LED, it would look like an oscillating dot, just
moving back and forth rapidly. Without understanding of how this works,
it would appear as "eratic operation". But to the contrary, this is the
proper operation for the sensor.

John Rodgers
88 GL Driver

Jbclem wrote:
>
> I'm measuring the voltage output from a new oxygen sensor(w/disconnected
> wire) and getting an erratic result.  For a while I could adjust the air
> flow meter spring tension so that the voltage was around .55 to .65v, then
> it went up to .88-.90 and I can't get it down, even when I adjust the spring
> tension all the way either way.  Loosing(richer) the spring tension moves
> the voltage reading up above .90 but tightening it(leaner) doesn't produce a
> voltage below .88, even though when I tighten it enough I can feel an engine
> miss developing.
>
> Sounds like a bad air flow meter, but I'm not sure.  Any suggestions? When
> the air flow meter goes bad is it usually a problem with the spring(broken?,
> lost its tension?).
>
> John
>
> 1983 Westphalia, water cooled