[papachivas]

Measurements done. No cylinder is below 12 Bar / 180 PSI.

Hello friend for the BMW that use the N63 engine we have many problems.
The most common.
Spark plugs. For spark plugs I always use NGK Bosch I always have problems. Never forget to use the I'm torquemeter and apply the correct torque to the spark plugs. Ignition coils. All air intake ducts and ventilation tubes are recessed to replace.
 Carry out a check to break the lack of tightness in the air intake system from the main entrance, including the turbo pressurization system.
Carry out a chain test when the wear of the parts that make up the engine distribution system (chain, tensioner, chain guide, gutters, etc.)
Here in Brazil, there is a BMW measure that includes replacing all fuel injectors high pressure fuel pumps all engine ventilation tubes vacuum pump flow sensors timing chain low fuel pressure sensor if everything applies to the vehicle .this you can check directly at a BMW dealer if you have anything related to your vehicle.Do not forget that everything I said, regardless of being applied by BMW, has a verification process before replacing any part. 
Don't forget to check that the low fuel pressure system is 100% functional so as not to misdiagnose it.
Make a diagnostic strategy and do not skip any steps to find the cause of the problem and not make mistakes.
Remembering that injectors must never be installed in the same bank with different injector index. Equalize the injectors after adapting them.
If you want to provide the chassis number, I can see if my system can see if your vehicle has any measurements.
When applying the BMW measurement, it is necessary to program the DME unit.
I'm not saying all this because I saw someone say it, but because I did it a lot when I worked at the BMW dealership here in Brazil for 8 years and 3 years ago I'm not there anymore.