From: "Mark Keller" <tyler@ISLANDNET.COM> To: <vanagon@GERRY.VANAGON.COM> Sent: Saturday, February 03, 2001 3:44 PM Subject: Re: O2 Sensor Voltage
> In other words if the fuel injection system is in proper > adjustment, you should be able to disconnect the O2 sensor, and read the > voltage from the O2 sensor black wire. Open loop voltage is very stable > and should be in the .5 volt range. I'm not sure this is correct. Doesn't "open loop" mean the ECU isn't receiving a signal from the O2 sensor, and operating in its "default" mode? Once the O2 sensor is sending a signal, the ECU goes into "closed loop" mode, meaning it's using the voltage generated by the sensor, which is in turn affecting the sensor's voltage. If you look at a graph of O2 voltage output vs. air/fuel ratio you see a reversed "S"-shape which is *very* steep right around the "correct" output. In other words, very *unstable.* What you may be thinking of here is that in a correctly adjusted system CO output (as measured by a gas analyzer) will be just about the same with the O2 sensor connected as with it disconnected, thereby giving the maximum range of adjustment. ---------------------------------------------------------------------- ----- Tom Young tomyoung1@home.com Lafayette, CA 94549 '81 Vanagon ---------------------------------------------------------------------- ----- |
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