One of my blog readers asked a logical question: Maybe, for some reason, the 6th cylinder is being spared?
In this entry, logical decisions for/against and types/solutions, which could be used, are provided.
If you ask me, are there any driving conditions in which some (not even the exact 6th cylinder) has to be maximally spared? I would say – in rapidly changing modes. Yes, of course, DME of this generation uses the principle of the energetic model and bases all calculations on the intake pipe model (simulates the performance of the virtual engine in real time); however, a non-optimal prognosis can happen. In rapidly changing modes, also the short-term correction tools (starting with the fuel corrections, finishing with all types of the actuators: throttle management, WG, etc.) will not have enough time to react, if something in the prognosis will go fundamentally wrong.
Are these considerations attributable to the reduced efficiency of the 6th cylinder (description here)? No, the efficiency of the 6th cylinder is reduced exactly in the stationary/even driving conditions!
Ok, many people on the Internet are talking about overheating of the 6th cylinder. I think you don’t see any basis for such assumptions. Neither common sense nor a thermal camera confirms any problems (at least, overheating of the engine block). But, even if the problem were (internal/local) overheating in the conditions or heavy load, I have a question – why is the 6th cylinder “spared” by 1500 .. 2000RPM and a load of 50 .. 100Nm? It is not more than 5 .. 10% of the maximum power of the engine. Accordingly, if the 6th cylinder should be spared by such low load, in full power, the engine should “undress” without thinking!
And finally, lean fuel mixture is not sparing for sure! Sparing (for example, from knocking in transition processes) would be a rich fuel mixture! Lean fuel mixture is the fastest road to knocking and misfires!
Unfortunately, no, I do not have any ideas how BMW would try to spare something by such methods.
