Really diving into details there @Tester and missing the big picture.
They are listed as oxygen sensors on parts websites, in the Bentley manual, and everywhere I read about the two oxygen sensors for my car. Perhaps mechanics cll my oxygen sensors air/fuel ratio sensors, I do not know. But none of the facts change becuase of what they are called.
@sgtrock21 The EPA estimate is always on the conservative side and that my nine year old car with 77,000 miles on it gets nowhere near the EPA estimate is the problem. Of course I have no idea how the car was driven before I bought it at 70,000 miles. The slighty melted plastic of the intake manifold indicates it was driven badly. My whole point is that the car doesnāt get anywhere near the mileage it should and jumps all over the map so something is obviously wrong.
The compression test is the best advice so far and will be done tomorrow.
Theyāre referred to as o2 sensors or oxygen sensors in the service data Iām looking at. Iām not sure if that means they really are the traditional narrow band sensor, or they are in fact the wideband air-fuel-ratio sensor. On the electrical schematic, the section where the power-train control circuit is shown is referred to as ālambda controlā. By the looks of the circuit, the pre-cat sensor has 3 current outputs, labeled
alsvr1 (GE) - Yellow
alsvp1 (WS) - White
ilsvp1 (GE) ā Yellow
Apparently GE mean āyellowā and WS means āwhiteā in mini-speak , referring to the wire colors I guess.
The current outputs are converted to voltages by transistors located on the āDME Control Unitā.
Given that the outputs appear to be currents, Iām presuming these are wide-band air-fuel ratio sensors rather than narrow band sensors. The post-cat sensor is slightly different, and only has 1 output, and that appears to also be a current output, implying it is a wide-band air-fuel ratio sensor.
I concur that the diagnostic process would be less ambiguous if the nomenclature used by the car manufacturers was consistent.
and now for some hard data.
Compression test:
Cylinder 1 - 160psi
Cylinder 2 - 156psi
Cylinder 3 - 162psi
Cylinder 4 - 172psi - Oil on spark plug threads
Crankcase pressue test:
I believe spec is 38mbar but that is from online as I cannot find it in my Bentley manual.
At idle 55-70mbar
At idle with PCV plugged - -5 to +10mbar
So the compression test looks good to me except the spark plug gasket on cylinder 4 is failing or failed. Could the leak on cylinder 4 cause the frothy oil and bad crankcase pressure? I am thinking about doing an oil pressure test or testing the fuel injectors but donāt know if they would be useful.
My next door neighbors own a 2014 Mini. They love it. I have driven it and liked it. I have also driven 2 vintage British Mini Coopers. One was the only right hand drive vehicle I have driven. It was no problem on USA roads but I donāt know if I could successfully drive anything on the wrong side of the road. I could probably do OK on a rural roads but turns in traffic would be counterintuitive.