Date: Mon, 18 Dec 2000 17:24:12 EST
Reply-To: CMathis227@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Chuck Mathis <CMathis227@AOL.COM>
Subject: Re: O2 voltage when cold
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Jim,
My '85 (with a brand spankin' new O2 Sensor inside a sparkling new set of coated pipes) starts up showing 410mV then climbs to 710mV then bebops all over the place once I get going. I don't think the O2 Sensor itself would cause your problem even if it wasn't working properly (I've been very wrong before). I had a cold idle problem last year that I traced to the throttle position switch. Is your TP light on when you don't have your foot on the gas? If it is not you need to adjust or replace it. If the light is on the problem might be the warm air valve. I'm not sure where this is on a 2.1L but you'll need to find the hose and squeeze it to cut off the airflow. If the idle speed drops it is working fine. If it doesn't change you have a problem there.
Chuck
'85 Wolfsburg Westy -- 'Roland'
In a message dated Mon, 18 Dec 2000 4:34:43 PM Eastern Standard Time, James Creech <jacreech@VISUALLINK.COM> writes:
<< Anyone with a Digitool or who has otherwise measured the voltage the O2
sensor puts out at cold idle (first start up)? I am trying to diagnose my
cold idle problem and have eliminated most everything. However, I noticed
today with the Digitool connected (great tool, Darrell!) that my cold start
up gives an O2 reading of 400 mV which slowly rises to about 650 mV. The
engine won't keep running and needs several starts at that lower voltage
until it rises to about 500 mV, at which point the engine stays running
(idle) - from there up to about 650 mV, which I'm guessing is the correct
idle enrichment value. Then a couple of minutes later the ECU goes into
closed loop and my O2 readings vary above and below 500 mV, as they should.
All my other components seem ok (temp 2, AFM, idle stab. valve and its
control unit all test ok). Does the fact that my engine stalls out at cold
start up with the low voltage reading at the O2 sensor (400 mV) say anything
helpful to diagnose my problem? BTW my O2 sensor is the heated type.
Perhaps the slow rise from 400 mV to 650 is only due to it heating up?
Thanks,
Jim Creech
87 Westy 2.1
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