BesideTheBox

Can anyone tell me how quickly the pre-cat O2 oxygen sensors should cycle at idle and at, say, 2500 rpm?

What I see on my car with an OBDII live data scanner:
Idle: 1 cycle in ~2 seconds
2200 rpm: 1 cycle in ~1 second

At http://www.aa1car.com/library/o2sensor.htm, they say that a multiport fuel injected engine should cycle 5 to 7 times per second at 2500 rpm.

As Porsche is 'special', I'm not sure if this applies.

Anyone here have specific O2 sensor cycle specifications or observations?

Thank you for the input!

BesideTheBox

A fellow rennlister sent me some Bosch O2 oxygen sensor documentation that cleared up some things for me. And perhaps saved me some money.

From the Bosch documentation:
2. With engine speed at ~ 2000 RPM the sensor voltage
should be seen to cycle smoothly between 100 – 900
mV (0.1 – 0.9 Volts) approximately eight times every ten
seconds, as shown in Fig. 1.

You can find this fantastic document at http://www.bosch.com.au/content/lang...r__Cat_WEB.pdf.

The document contains information on

• oxygen sensor types
• oxygen sensor evolution
• construction and operation
• system application
• sensor testing
• causes and effects of oxygen sensor failure

Enjoy!