O2 Single wire Output voltage - Golf mk3

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Tue 30 Jan 2007 15:23
O2 Single wire Output voltage - Golf mk3 - Peter D
Golf MKIII ABS 1.8 single wire O" sensors. It is cycling but 0.2 to 0.7 volts whilst in circuit. I was expecting 0.1 to 0.9 at least. Any ideas the data book does not define the scale of the display. Regards Peter
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Tue 30 Jan 2007 19:52
O2 Single wire Output voltage - Golf mk3 - Another John H
If it's a zirconia sensor have a look here:

www.picotech.com/auto/waveforms/lambda_zirconia.ht...l

My limited experience of these things puts your figures about right, but you've missed an important fact out, which is the frequency of "switching".
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Tue 30 Jan 2007 20:15
O2 Single wire Output voltage - Golf mk3 - Peter D
Excellent, thanks for your response. It is a Zirconia and clearly is well in the ball park. It is switching 2 to 3 times a second. not quite as evenly as the example close enough to convince me it is not the O2 sensor that is causing a slightly rough tickover, the car runs well and perfect when cold to cool but once the car reaches 70 degrees or more the slightly rough idle starts. I've checked all over for air leaks, gaskets, throttle boby isolators, pipework, breathers, purge valve and cans, everthing. Any ideas welcome MOT on Thusday although according to the O2 sensor it will probably pass the emissions ok. Regards Peter
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Wed 31 Jan 2007 08:57
O2 Single wire Output voltage - Golf mk3 - Peter D
Re check the sensor and it appears to be fully working. Did an emissions test this morning, spot on Lamda 1.000 no sign of a problem Still can not find the slight roughness at tick over. Compressions all fairly equal, leakages are all very similair, runs well. Mystery. I have an Alpha-Bid.com OBDII cable and Vag-com 409.1 S/W but at the moment I can not get the S/W to recognise the cable nevermind my ECU. Regards Peter
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Wed 31 Jan 2007 20:25
O2 Single wire Output voltage - Golf mk3 - Another John H
It might be worth a clean of the insides of the throttle body and edge of the butterfly valve, as these can get gummed up and not "open" cleanly when expected to.
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