Abstract: A method for entering and exiting cylinder deactivation modes in a diesel engine, comprises monitoring an engine speed from an idle engine speed to a governed engine speed and monitoring an engine load. If the monitored engine speed is the idle engine speed up to the governed engine speed, and if the engine load is less than the predetermined low load condition, then implementation of a cylinder deactivation mode is restricted to one of a 2 cylinder deactivation mode, a 3 cylinder deactivation mode, or a 4 cylinder deactivation mode. A cylinder deactivation mode is selected for engine operation among the 2 cylinder deactivation mode, the 3 cylinder deactivation mode, and the 4 cylinder deactivation mode to operate the engine at an effective frequency that avoids two resonant frequencies of the vehicle and to operate the engine below a torsional vibration limit.

Abstract: When selecting cylinders of a multi-cylinder diesel engine in an engine system for cylinder deactivation (CDA), a method can comprise designating a first resonance around a first periodic frequency output of the engine system as a primary boundary and designating a second resonance around a second periodic frequency output of the engine system as a secondary boundary. Selecting cylinders can comprise selecting one of half, one third, or two thirds of the multiple cylinders for CDA while firing the remaining multiple cylinders. The selection can be made so that the periodic frequency output of the engine is between the primary and secondary boundaries. A compact periodic frequency band can be implemented to further restrict the selection of cylinders for CDA. The first periodic frequency output can be about 15 Hertz+/?1.5 Hertz and the second periodic frequency output can be between 30-40 Hertz+/?1.5 Hertz.

Abstract: A method for entering and exiting cylinder deactivation modes in a diesel engine, comprises monitoring an engine speed from an idle engine speed to a governed engine speed and monitoring an engine load. If the monitored engine speed is the idle engine speed up to the governed engine speed, and if the engine load is less than the predetermined low load condition, then implementation of a cylinder deactivation mode is restricted to one of a 2 cylinder deactivation mode, a 3 cylinder deactivation mode, or a 4 cylinder deactivation mode. A cylinder deactivation mode is selected for engine operation among the 2 cylinder deactivation mode, the 3 cylinder deactivation mode, and the 4 cylinder deactivation mode to operate the engine at an effective frequency that avoids two resonant frequencies of the vehicle and to operate the engine below a torsional vibration limit.