I don’t think it is a bad sensor. The old and new both give the same readings which is a jumping from -.01 to .01. Perhaps it is a massive air leak and CRC throttle body cleaner doesn’t effect the engine. Does anybody know if it should work for finding leaks or do I need carb cleaner?
I was chasing similar argument when trying to repair my 2006 Pathfinder, and what I concluded to myself in the end was that OBD2 reported live data may be misinterpreted by some generic diagnostics apps.
I had similar issue where one bank was reporting overly reach, another as super-lean… when using OBD2 diagnostics from some $10 Android application.
In reality, I found a substantial exhaust system leak, which was making all sensor readings skewed and ECM was pretty much saying “hey guy, your sensors readings make no sense”, which I believe is somewhat similar to your case.
So… after I fixed the real problem of leaks in exhaust system… I checked upstream live data reads and they were still reporting teh same “lean” / “rich”, but by that point I knew it was a wrong data interpretation, not the actual problem.
Just my 2 cents…
If that were the case, the idle RPM would be way too high. We are talking about a leak so large that the full flow of the injectors could not overcome it.
If 2 sensors read the same and you believe the software you have, that points to an electrical connection problem between the sensor and the ECU or IN the ECU. The symptom of very poor fuel economy points to the same thing, the injectors are adding fuel for air that isn’t there and actually being rich rather than lean as your O2 sensor is reading it.
Another idea: Narrow band sensors work on their own, they produce their own output voltage with no input power other than the exhaust heat. Wideband sensors on the other hand require an input voltage (power source) to work. Wideband sensors don’t produce a voltage, they produce a current that’s proportional to the O2 concentration in the exhaust stream. that has to be converted to a voltage by another circuit. Where that other circuit is located, on the sensor or elsewhere, don’t know. Wideband sensors also require a bias voltage input of 0.45 volts applied so the chemical reaction that produces the current output works correctly. So the problem could be the sensor or its circuit isn’t receiving the necessary input reference power/voltage bias for some reason. It’d be like when the power to a light bulb gets cut off, the light bulb turns off. The light bulb itself is still good, it just doesn’t produce any light b/c its input power source is missing. In the case of a sensor, it might be ok, but it produces an output of 0 volts if its input power source is missing.
Now this is helpful troubleshooting. I will take the voltmeter out today and do some exploring. No idea how to check the ECU though.
I didn’t reset the ECU after replacing the sensors. Is this needed? Just unplug the negative terminal for an hour or two I mean.
and an additional piece of info since I have never changed oxygen sensors before and don’t know if this is how it should be. The upstream was covered in soot while downstream had much less soot on it.
My 2010 Kia Forte SX 2.4L I4 6spd M/T averages about 25mpg in the Winter with 87 octane Winter formula fuel. Your fluctuating mpg of 20 to 30 mpg sounds normal to me. My Summer average is about 28mpg.
I disagree @sgtrock21
The EPA estimate for my car is 26/34mpg. Every car I have had the past twenty years got above the EPA estimate and within 2mpg each fill up. My previous fill-ups are 25.2mpg, 24.8, 21.7, 23.6, 24, 29, 26.5, 27.8, and 22.6. Most are below even the city driving EPA estimate and the variance is far too wide.
The key word regarding EPA estimates is ESTIMATES. Actual (real world) results may vary. The tests are conducted on new vehicles under strictly controlled conditions. You have owned your 2010 Mini Cooper S for 9 months. Was all scheduled maintenance correctly performed according to mileage/time requirements? Did the previous owner never abuse a turbo car? How many miles are on your 9+ year old Mini? My current Kia and previous Mitsubishi Eclipse RS 2.4l I4 5spd M/T were purchased new and received all scheduled maintenance. They both could exceed EPA highway mpg which was 36mpg. On long highway trips at 65mph they would get 40+mpg traversing substantial mountain ranges.
There has been several mentions about the state of the oil. Do you have coolant in your oil? Has your cooling system stayed full with no problems? The overheating combined with vibrations at idle as well as oil consistency questions begin to point heavily toward cylinder head issues or valve problems possibly.
Hows about we get those compression readings before trying to diagnose? Everything needs to be sound mechanically before looking to solve other symptoms. You can chase your tail pretty hard when you are looking into readings and run quality by assuming everything is cool mechanically. Who knows what readings manifest when the engine isnt running properly from a mechanical perspective. Compression readings are important in this instance.
No coolant in oil or problems with the coolant. From what I have read the froth in the oil cap is from air getting into the crankcase. The coolant level has not changed since it was flushed. The overheating was from the previous owner as indicated by the slighty melted plastic intake manifold.
I will do a compression test and crankcase pressure test tomorrow and post the results.
First of all, there’s a big difference between an O2 sensor and an Air Fuel Ratio sensor.
Using the correct terminology would avoid a lot of confusion.
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 doesn’t 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.
I’ve always found that nothing can be diagnosed unless it’s understood how the system works.
They’re referred to as o2 sensors or oxygen sensors in the service data I’m looking at. I’m 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 “lambda control”. By the looks of the circuit, the pre-cat sensor has 3 current outputs, labeled
- alsvr1 (GE) - Yellow
- alsvp1 (WS) - White
- ilsvp1 (GE) – Yellow
Apparently GE mean “yellow” and WS means “white” in mini-speak , referring to the wire colors I guess.
The current outputs are converted to voltages by transistors located on the “DME Control Unit”.
Given that the outputs appear to be currents, I’m 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.
Its German for some reason.
GE - gelb
WS - weiss
German… for some reason? LOL It has a very specific reason.
and now for some hard data.
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 don’t know if they would be useful.
Are you referring to Bavarian Motor Works?
Indeed I was…
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 don’t 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.