The limiter is rather smart.....
The limiter in an M119 engine is rather smart compared to old systems, it operates at 2 stages at least. First the ecu uses the cam variation system to reduce the power once you are getting close to the set top speed which usually is 155mph. now if for some reason the reduction in power by the advancing of the intake cams is not enough to limit the top speed, the ecu will revert to a more conventional method of cutting fuel and ignition. This is why the limiter on your car is rather a soft one and feels more like the engine is running out of power. Usually advancing the intake Cam pushes the power band to a lower rpm range. In the M119 engine in normal driving below 1500rpm the intake cam set to zero setting which I believe is slightly retarded compared to a non variable cam equipped engine. This allows the engine to start easily and have a smooth idle. Above 1500 rpm and up to 3750rpms the cam is advanced (I have no idea about the degree of advance used, I think it is rather dynamic) this gives your car its lovely mid range torque and throttle response. Above 3750 the cam is set back to zero setting giving the engine the top end breathing to give high power output. Now if the ecu detects that top speed is reached it then advances the cam again reducing the power at topend thus lowering the ability of the car to go over speed. Yet if the plugs of the cam shifting units are removed the ecu limits power by cutting fuel.
