MINI R56 2009

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MINI R56 2009

Postby Technician » Thu Aug 31, 2017 12:49 am

Had this car left with me this morning, didn't think she was turning up but anyway...

The car is a Mini R56 engine N12B14A. The customer was complaining about the engine running rough, she advised the revs would go up and down while driving. She also advised that the instrument display had a EML warning lamp illuminated.

Investigation

I started the car to move it into the garage, immediately it was noticed that a noise was present from the engine. A look around the engine and checking the oil and water established the usual never been checked for oil or water. I drained the oil and less than a litre was recovered, I feared the worst at this point given it is the Peugeot engine and the VANOS units can and do play up.

I decided to flush the engine and then put new oil and filter in, the engine at this time ran much better and quieter. While the original less than a litre of oil was draining I spent a good few minutes looking around the engine bay, items like the air intake trunking was seen to be loose, lambda sensor bank 1 sensor 2 electrical wiring was left hanging and insecure, a seepage of oil from the rocker box cover was noticed. I think this is valuable time spent to include these findings in the technicians report to the customer when required.

Now I put the VERUS on the car and read for fault codes, two such codes were present, they were;

1 / 2A56 - Oxygen sensor heating after cat malfunction, and

2 / 2B68 - Air Mass Flow plausibility.

Having spent that initial five minutes or so examining the engine bay I am not surprised to find the code 2A56, although benefit of the doubt at this time should be given until tested as it could be a code from previous work not deleted.

The Air Mass Flow fault code after inspecting under the bonnet initially made me stop and think because I had not noticed an air mass meter fitted, a second look confirmed that indeed the air mass meter is not fitted to this model.

A look at the wiring diagram confirmed that the engine management system has a combined MAP/IAT sensor fitted. I also decided that it would be good working practice to check with the dealers for any TSB's that may have been issued. According to the dealers such a TSB had been issued regarding the fault code DTC 2B68, which refers to the engine management system having faults present due to the exterior temperature sensor, which shows up as 'Air Mass Flow Plausibility'. The TSB instructs the technician to check the instrument cluster for temperature displayed as this could be plausible to the outside temperature. In this vehicle I did not find any fault in this circuit.

I moved on to test the 2A56 code circuit, the oxygen sensor fitted was the four wire type, and as we know there are two different types of four wire sensors, the Titania and the Zerconia type. As the fault code was referring to the heater circuit, this is the circuit I checked first.

Referring to the manufacturer technical data working from the ECU connector (back probing) terminal B17 according to the wiring diagram advised that B17 should supply battery voltage from the ECU to the heated oxygen sensor terminal 1, which should also while connected supply battery voltage to ECU B18. This is a good check to be completed from the ECU terminals because it not only checks the continuity of the wiring, but also the heater circuit through the lambda sensor. The voltage was recorded at 1.31V at both ECU terminals B17 and B18. At this point I am leaning towards an ECU fault, but not yet established.

With the engine idling the ECU should provide a PWM signal from terminal B18, the reference voltage and time being 5V/0.5 sec. The oscilloscope did not trigger at all at these settings, only when I altered the scope voltage settings to 0.2V/0.5 sec did the trace appear, but the amount of hash/noise clearly indicated to me that the ECU was not capable of providing a PWM signal.

As the oxygen sensor on this car creates its own voltage when the temperature rises, this I based my understanding on the fact that the sensor produced no voltage at terminal B24 until the engine temperature warmed up, the actual voltage was greater than the Bias voltage I had previously observed on the VERUS at 0.75 V fluctuating, the technical data advising around 0.6V. The oxygen sensor had a good ground connection showing zero volts, and the ECU terminal B29 linked to B17 was also recording 1.31V. I am convinced the type of sensors fitted are the Zirconia dioxide type.

I'm not sure what electricians might think the differences are between testing wiring using a voltage supply and a bulb against the HOOK, however initially I decided to take the safe option and check the wiring using the ohmmeter, the only readings that I was able to establish were 0.00 ohms, at this point I was confident that the wiring harness was in good working order, so then as a second test I used the HOOK and load tested the wiring, then checked with the ohmmeter again recording 0.00 ohms.

My conclusion to this diagnosis is that the ECU is not supplying a voltage from terminals B17 and B29 to the lambda sensors, nor is the ECU providing a PWM signal from B18.
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Re: MINI R56 2009

Postby AuthorMike » Thu Aug 31, 2017 6:20 pm

Any update on this, sounds interesting.

If only a PicoScope was owned & used, this has the makings of a great case study.
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Re: MINI R56 2009

Postby Liteace » Thu Aug 31, 2017 7:00 pm

Check ALL ecu supply voltages, could have one missing, fuses, there's 3 or 4 on this for engine ECU supply
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Re: MINI R56 2009

Postby Technician » Thu Aug 31, 2017 7:24 pm

AuthorMike wrote:Any update on this, sounds interesting.

If only a PicoScope was owned & used, this has the makings of a great case study.


Very true Mike, and although I might not get the opportunity on this occasion to use a Pico on it, there be other opportunities I'm sure where I can use it and a video presentation as well.
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Re: MINI R56 2009

Postby Technician » Thu Aug 31, 2017 7:26 pm

Liteace wrote:Check ALL ecu supply voltages, could have one missing, fuses, there's 3 or 4 on this for engine ECU supply


Thanks Liteace. I was not sure whether the car was being taken by the customer or not, but today it seems the car has been left with me, so after I speak to the customer, hopefully I'll see this through to the end.

Added info;

Tested the voltages through the fuses, according to the wiring diagram there are 8 fuses as power supplies that I have found, each one is live while the engine is running, and there is an ignition controlled relay activated by the ECM pin 85, so only 1.33V present unless engine running, but I need to remove the covers of the ECM plugs to back probe the terminals at the ECM to establish correct voltage at the ECM pins while the engine is running to be sure, this I'll have to do now over the weekend as time is not available. I'll also load test the wiring to confirm fitness.
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Re: MINI R56 2009

Postby STC » Thu Aug 31, 2017 11:04 pm

The car is a Mini R56 engine N12B14A. The customer was complaining about the engine running rough, she advised the revs would go up and down while driving.


So we have female driver, and an engine that starts up and is driveable albeit with an EML and running not as well as it should.
two such codes were present, they were;
1 / 2A56 - Oxygen sensor heating after cat malfunction, and
2 / 2B68 - Air Mass Flow plausibility.



Referring to the manufacturer technical data working from the ECU connector (back probing) terminal B17 according to the wiring diagram advised that B17 should supply battery voltage from the ECU to the heated oxygen sensor terminal 1, which should also while connected supply battery voltage to ECU B18.


No !! Not with the Engine Running, particularly when cold. I get the "No VD if No Current Flow" theory. Add to that you do not have the Prerequisites in place if you are testing an O2 with it switched off. Checking pulses in a cemetery - it would be a labour of love with little fruit.

This is a good check to be completed from the ECU terminals because it not only checks the continuity of the wiring, but also the heater circuit through the lambda sensor.


It proves the law of VD - nothing more of relevance with the fault code you have.

The voltage was recorded at 1.31V at both ECU terminals B17 and B18.


Really, that would be incredible !!
B17 & B29 (Kind thanks to Autodata) Push B+ to Both O2's and all 4 Injectors. You claim this engine starts - Yes ?
Then you have a dead ECU AND a broken wire between B17 and the splice in the loom.

At this point I am leaning towards an ECU fault, but not yet established.

Far from established! Lots of graft to do before that can be a twinkle in your eye.


With the engine idling the ECU should provide a PWM signal from terminal B18,

The engine does run.. and Yes BUT in the absence of 2A56 !!


the reference voltage and time being 5V/0.5 sec. The oscilloscope did not trigger at all

The heater runs at NBV not 5v, that should dictate your settings. 0.5 s is too much time across the screen to see the plausibility test and rejection, not that Voltage would show that. The ECU employs other, more meaningful means to rule over the territory that is the eternal ruler of.

at these settings, only when I altered the scope voltage settings to 0.2V/0.5 sec did the trace appear, but the amount of hash/noise clearly indicated to me that the ECU was not capable of providing a PWM signal.


Not capable or not willing ???

As the oxygen sensor on this car creates its own voltage when the temperature rises, this I based my understanding on the fact that the sensor produced no voltage at terminal B24 until the engine temperature warmed up, the actual voltage was greater than the Bias voltage I had previously observed on the VERUS at 0.75 V fluctuating, the technical data advising around 0.6V. The oxygen sensor had a good ground connection showing zero volts,

So it can work without a heater in another galaxy (not a ford galaxy) ???

and the ECU terminal B29 linked to B17 was also recording 1.31V.


B17 & 29 are a doubled up parallel B+ from Ecu to both O2's and all 4 Injectors. Does this thin fire up and run or not ????? Have you fitted 1.31v Injectors ???? Do you have fault codes for Both O2's, if not why not ???

I am convinced the type of sensors fitted are the Zirconia dioxide type.

Does it matter ?? Heater circuit's are not dissimilar on any of them - just like an electric soldering irons or glow plugs. schoolboy physics. I speak for myself.

I'm not sure what electricians might think the differences are between testing wiring using a voltage supply and a bulb against the HOOK,


You would need to have studied the strategy of the hook, what is its criteria for a hot shot pass or fail ? Does it vary for individual circuit load or is it Dumb to that.

As for the bulb, no one would knock you for using a 55w bulb to test a 55w headlamp circuit.
I have the Hook, a decade box and a variety of bulbs for varied occasions.

however initially I decided to take the safe option and check the wiring using the ohmmeter, the only readings that I was able to establish were 0.00 ohms, at this point I was confident that the wiring harness was in good working order, so then as a second test I used the HOOK and load tested the wiring, then checked with the ohmmeter again recording 0.00 ohms.


You took the wrong option 0 ohms confirms that you do not have an open circuit - nothing more. The insides of that O2 could be a molten mess !!

My conclusion to this diagnosis is that the ECU is not supplying a voltage from terminals B17 and B29 to the lambda sensors,


17 and 29 fire up both O2's and all 4 injectors - tell me the car starts and idles just one more time - Please I beg you !!!

Not conclusion, findings!!
nor is the ECU providing a PWM signal from B18.

Very true - Cause or Consequence ??

The Devil is in the Detail :arrow: :arrow: :arrow: :arrow:

You would do well , from an ethical stance, to bin your time so far. Bolt a genuine O2 on it then pass it on if that does not cure it.
All is not lost that way for our audience.
Last edited by STC on Thu Aug 31, 2017 11:30 pm, edited 1 time in total.
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Re: MINI R56 2009

Postby Dcunning35 » Thu Aug 31, 2017 11:21 pm

This is confusing me the lack of pwm control of a post cat oxygen sensor ,not sure how this can effect fueling if shorted yes if linked to upstream heater I have seen lots of drops in upstream o2 sensors caused by downstream circuits an easy spot with the pico.
Has the air mass plausibility dtc returned or either dtc when cleared .
Have you any freeze frame data in conjunction with dtcs
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Re: MINI R56 2009

Postby Liteace » Thu Aug 31, 2017 11:26 pm

STC wrote:

B17 & B29 (Kind thanks to Autodata) Push B+ to Both O2's and all 4 Injectors.................................


Oh dear, you use A.D for wiring diags :lol:
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Re: MINI R56 2009

Postby STC » Thu Aug 31, 2017 11:32 pm

Liteace wrote:
STC wrote:

B17 & B29 (Kind thanks to Autodata) Push B+ to Both O2's and all 4 Injectors.................................


Oh dear, you use A.D for wiring diags :lol:


I have WDS, ICOM, and an Account with BMW Tech Info. Just shout if you need any thing.
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Re: MINI R56 2009

Postby STC » Thu Aug 31, 2017 11:40 pm

Dcunning35 wrote:This is confusing me the lack of pwm control of a post cat oxygen sensor ,not sure how this can effect fueling if shorted yes if linked to upstream heater I have seen lots of drops in upstream o2 sensors caused by downstream circuits an easy spot with the pico.
Has the air mass plausibility dtc returned or either dtc when cleared .
Have you any freeze frame data in conjunction with dtcs
Danny

A blown fuse would display the same symptoms. Some times we don't know what we don't know yet mask it behind 100 years of experience, 100 years of getting It wrong qualifies as experience.
Here we have all 4 injectors running on Bluetooth but erratically :o :o :o
I do despair. Have no wish to be associated with these people. Commercial Heating and Cooling systems is my future.
Last edited by STC on Thu Aug 31, 2017 11:50 pm, edited 3 times in total.
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