I agree with njaremka, but just wanted to add that you can use an adapter for your MAP sensor to give you a good place to measure intake manifold boost/vacuum using a standalone gauge, such as this one: . I haven't personally used that one, so don't take this as an endorsement, just an example of what I am talking about. This should give you the behavior you are expecting, assuming all is working well.

Personally, I use an OBD II Scantool to measure boost/vacuum using the factory MAP sensor. If you have one lying around, this will certainly be the easiest way, plus you can usually show max/min values, so can see what was happening while driving without staring at a gauge.

 

Ok, I understand. Thanks for that.
My confusion is here at this video:
It says for N18, positive pressure of 36 mBar.

Going to my misfire problem, I have done almost everything:
- Coils
- Spark plugs
- Solenoid vanos
- All pressure sensors
- Position sensor
- Camshaft position sensors
- Leak test
- Diverter Valve and spring change to ALTA model
- Valve stem seals (changed them without dismantling the head)
- Checked timing
- Fuel filter
- MAF
- O2 sensor (pre cat)
- Software update
- Compression test
- Stroboscopic inspection
Pending (besides de PCV system) are: valve seats (I have seen some threads about N18 engines having this problem), injection system, wiring.

Cooper S, 2012, Manual, 100.000 km.
I have intermitent misfire under specific conditions. Idles fine cold or hot, runs great under hard conditions. Problem appears when going down hill...no load, mid RPM range. Six months ago it was Cyl 2 and 3 which misfires, now it is 1 and 4. Car moves to limp mode. I stop the car, starts and all fine until the next limp mode (once a day app). I can also clear the codes while running (Creator C501) and all is fine until next limp mode. I do not think is the injection system as it randoms from 2 and 3 to 1 and 4...

Anyway, my first time I have Mini and it is getting personal :-). I want to fix it before I trash the car.
I bought it to have fun only...I do not nee it for daily use.

 

Let us know what the code is and what your fuel trims (long and short term) are, as this information would help in diagnosis. Also, when coasting (i.e. no load, mid-RPM) the fuel injectors should be completely disabled, so no misfire should even be possible.

Regarding the video, I believe that the creator meant -36 mbar, despite the numbers being written as 36mbar, since the list of causes at the end stated "excessive underpressure", which, to me, sounds like some vacuum is expected (i.e. just not an 'excessive amount'). Excessive vacuum in the crankcase could be caused by a stuck PCV check valve, among other things. The PCV valve is supposed to limit the flow of gases under idle/max vacuum conditions to avoid such a scenario, although the mini, with its inherently low idle vacuum, may be a bit different to most other cars in this regard.

 

That video is a little misleading... It doesn't say if the spec should be positive or negative pressure. I would expect ~36 mBar negative pressure, if that is the spec.

 

Thank you.
Misfire (when Cyl 2 and 3 misfire):
General codes P0300, P0302, P0303
Specific codes:
2EFE
2F00
2EE0
2EE7
2F01
2EEA
2EF7
2EE7
I took a picture about the fuel trim at idle when warm:
Short term: -0.8%
Long term: -18.8%

Regarding the pressure at the oil cap, we agreed then that it should be -36 mBar (- 1 InHg app), so it should be ok. I will see if it varies when I change the valve cover tomorrow.

 

Thanks for the additional information.

Looks like the codes translate as follows:
2EFE - Fan 1 Control Circuit high
2EE0 - Coolant temp sensor, signal
2EE7 - misfire cylinder 2 fuel injection deactivation
2F00 - Misfire cylinder 2, damaging to catalytic converter or damaging exhaust gas
2F01 - Misfire, Cylinder 3
2EEA - temperature sensor cooler outlet
2EF7 - DME MAP THERMOSTAT, ACTIVATION
2EE7 - com misfire 2 FID

Based on these codes, I would say that you have a coolant temperature sensor issue that is resulting in improper fueling and/or timing. For example, when the car is cold, it will run much richer and substantially different timing (especially on the very low end, which usually goes down to -40F or so), but if the car doesn't know its own temp it will typically default to full cold settings, which could result in a misfire and general poor running. Also looks like you may have a radiator fan issue and possibly a thermostat issue.

Be good to check what the coolant temp sensor readout is using a scan tool, although these cars may use one coolant temp sensor for the ECU and another for reporting to the gauge, so even if you see reasonable values (e.g. ambient temp when the motor has been off for many hours), this does not conclusively rule out a failed temp sensor. To rule it out, you would need to look up resistance at various temps and directly test the sensor (on the bottom hose IIRC) to see if the measured resistance makes sense.

To confirm the thermostat (i.e. the octopus on these cars) is working, you can feel the upper and lower radiator hoses while the car is running; both should be quite warm. If one is cold, there is no flow through the system, either because of a lack of coolant or because the thermostat is closed (normal until the vehicle is warmed up though).

Hope that this helps!

 

What he said, I would replace the coolant temp sensor and see how that works out.

 

Thank you so much.
My scanner Creator C501 does not describe the error codes as you described. Lesson learnt:-(.
For instance 2EE0 says "Combustion misfiring, Several Cylinders: Fuel injection deactivation", in stead of "Coolant temp sensor, signal" :-(((((

I will proceed as suggested and will come back to you all.
Are the fuel values ok?.

 

BTW where did you get these code descriptions?.
My scanner provides different description. I am looking now at bmwfault.codes and found your descriptions, however there are several variants…so how to know which on is the correct one?.
Thanks

 

Hi there, I got my codes from here: https://mechanicalee.blogspot.com/20...-hex-code.html

That being said, I now realize that BMW codes may not apply to mini coopers; bad assumption on my part that they would and apologies for any confusion this assumption caused.

Regarding the long term fueling adjustment being ~-18%, this definitely indicates an issue. On a MAF-based car, this would indicate a stuck open injector or bad O2 sensor (an air leak would cause a lean condition and you would see positive fuel trims). On a MAP-based car, this could be evidence of an air leak (I'm not as familiar with MAP based issues, honestly). Not sure if your engine is MAF or MAP based, but wouldn't hurt to have the intake tract pressure/smoke tested to rule out air leaks.

 

No problem. I changed the temperature sensor yesterday. I did a trip about 50 km and no Limp Mode yet. Fuel trims are near zero (fluctuates between +4 and -2).
Temperature looks more "stable".
Let´s see how it works the next days.

 

Drove several days after changing temperature sensor. Once a day or every two days, same misfires, same codes + limp mode.
I recorded Fuel trims with OBD Link for half an hour, while it was working fine. Short term: -5 to +6. Long term: -3 to +4
Yesterday I took the intake manifold out. Checked the intake valves. They looked not bad at all (I did walnut blast them about 5000 km ago).
I will check with Picoscope if I can record the misfire when it happens.

BTW...I hate this car.

 

Tmap sensor on the charge pipe got slammed with oil and condensation. On a scanner you will probably see the charge pipe is saying it has a lot more pressure than manifold (after throttle boddy). This makes your car think it is already making boost. Turbo will not spool or will spool really last 3.5-4k rpm. If it is your tmap there's a good chance your map sensor(on manifold under airbox) got gooed too.