Thought I'd post some findings after data logging the O2 sensor.

It appears that the Mini might have a different cycling behavior at idle vs. driving.

My logging shows that driving at a constant speed (like on a highway) you'll get O2 sensor cycling around 1Hz or higher (cycle every 1 second or faster) between .8V and .1V.

At idle, this drops to around .3Hz (or a cycle every 3 seconds or so).

So if you are trying to tell if your O2 is slowing down due to age, keep this behavior in mind.

Either that, or my car is weird

 

Interesting. I'm used to seeing it cycle at about 1 Hz at idle as well. Keep us posted whether your sensor craps the bed in the near future. Thanks

 

It makes sense to me that it would cycle faster with hotter, higher velocity exhaust gas going by the sensor than at idle.
My old 1982 VW Rabbit with CIS was the same way whether the sensor was old or new.

 

Well - I'm trying to get a replacement sensor and see what it does - I'll post up my results.

 

While we are on O2 sensors, maybe someone can explain this. Last Saturday, my air/fuel ratio gauge wiring wrapped around my steering column and snapped since this happened, the car acts like it wants to die at times. I'm almost wondering if the wiring to the O2 sensor was damaged. I haven't had a chance to look at it yet. I also through an O2 sensor code. I've never seen a car run erratic before because of a faulty O2 sensor. To the OP, thanks for the data!!

 

Update-

Well, I finally got a correct, new o2 sensor installed. I've started another thread on that subject - basically, the Delphi OEM replacement sensor works great and costs like $100. The Bosch OEM sensor has a mis-boxing problem where many of the sensors in the box with the correct number are wrong for the Mini (I wonder if this is the source of so many folks saying a Bosch doesn't work, and the BMW/Mini OEM one does).

But anyways - the new sensor does the same thing the old one does, that is, it cycles at about a 3 second period at idle, and speeds up to better than 1 cycle per second at higher RPMs (like driving down a highway at a constant speed).

So I wonder what's different about my car (RMW tune maybe?) from what Helix13 is used to seeing?

I did notice that it takes a while for the sensor (old or new) to warm up in my car. Like several minutes. The heated sensors in my R56 and my Big ol' truck heat up in well under a minute (like 20-30 secs). I wonder if this is just characteristic of R53s, or if it's a problem.