Finally got my Mini Project running great and I have been monitoring some of the readings with a bluetooth OBD2 reader. The post Cat O2 sensor consistently reads .65 volts when I am cruising on the highway or anytime there is a very steady throttle.

I am curious is this is normal for these and what other people are seeing. I have read that .45 is normal for most cars. My mini idles/runs great, no codes, gas milage is a bit on the low side(low 20s per my calc/25 per car computer) so it seems like its running rich and the voltage seems to support that. Not sure what to do to get it to lean out.


02 Mini S, CAI, 15% pully, magnaflow headers and exhaust and 380cc injectors

 

I’ve heard the 380 injectors without a tune could cause a slight rich condition and lower MPG.

 

That would make sense, but the 380 injectors are a new addition and it was the same with the stock ones. I had been curious if they would change it at all so that’s one reason I had been monitoring it.

 

How are the long term fuel trims? Still near 0 +/- 3%?

The post cat voltage seems about what I see as well at idle. At speed, I see a fluctuating voltage .(.41 to .90v) as the sensor is reacting to the exhaust stream and measuring the oxygen content.

There’s not as much activity as the upstream as that one is seeing more oxygen before the gases get might hot in the cat.

What tool are you using to measure?

 

I am using an OBDLink MX+ and connecting it via Bluetooth to my phone. I hadn’t looked at this prior but I set it up and at idle long term fuel trim is steady at 1.6%. And for what it’s worth fuel rate at idle is .3 gal/hr

Thanks for the feedback. This is getting a little bit into the weeds but it’s hard to know what normal is sometimes.