A system according to the principles of the present disclosure includes a switching period module and at least one of a valve lift control module and a start-stop control module. The switching period module determines a switching period that elapses as a valve lift actuator of an engine switches between a first valve lift position and a second valve lift position that is different than the first lift position. The switching period begins when a measured position of the valve lift actuator corresponds to the first lift position and the switching period ends when the measured position of the valve lift actuator corresponds to the second lift position. The valve lift control module controls the valve lift actuator based on the switching period. The start-stop control module determines whether to automatically stop the engine based on the switching period.

A system according to the principles of the present disclosure includes a switching period module and at least one of a valve lift control module and a start-stop control module. The switching period module determines a switching period that elapses as a valve lift actuator of an engine switches between a first valve lift position and a second valve lift position that is different than the first lift position. The switching period begins when a measured position of the valve lift actuator corresponds to the first lift position and the switching period ends when the measured position of the valve lift actuator corresponds to the second lift position. The valve lift control module controls the valve lift actuator based on the switching period. The start-stop control module determines whether to automatically stop the engine based on the switching period.

A method for the rapid restarting of an internal combustion engine that is slowing down at a reduced supplied air volume, in which the supplied air volume is increased again following a detected restart request and an ignitable fuel/air mixture is produced by a fuel injection in an intake cylinder that is in the intake cycle when the supplied air volume is increased, and the mixture is ignited in the intake cylinder to produce a combustion in the power cycle of the intake cylinder.

A method for the rapid restarting of an internal combustion engine that is slowing down at a reduced supplied air volume, in which the supplied air volume is increased again following a detected restart request and an ignitable fuel/air mixture is produced by a fuel injection in an intake cylinder that is in the intake cycle when the supplied air volume is increased, and the mixture is ignited in the intake cylinder to produce a combustion in the power cycle of the intake cylinder.

A control unit is provided for a hybrid drive that includes an internal combustion engine and an electric machine. The control unit is configured to cause one or more drag torque reduction measures of the internal combustion engine to be terminated in preparation for firing the internal combustion engine. In addition, the control unit is configured to cause the electric machine to at least partly compensate for an increase in the drag torque of the internal combustion engine caused by the termination of the one or more drag torque reduction measures.

A control unit is provided for a hybrid drive that includes an internal combustion engine and an electric machine. The control unit is configured to cause one or more drag torque reduction measures of the internal combustion engine to be terminated in preparation for firing the internal combustion engine. In addition, the control unit is configured to cause the electric machine to at least partly compensate for an increase in the drag torque of the internal combustion engine caused by the termination of the one or more drag torque reduction measures.

A variable cylinder engine is provided. The engine includes an engine body having a plurality of cylinders, a cooling mechanism for cooling the engine body by using a coolant, and a controller for controlling a temperature of the coolant and changing the number of active cylinders according to an operating state of the engine. The controller reduces the number of active cylinders in a reduced-cylinder operating range set within a partial engine load range, and expands the reduced-cylinder operating range to a higher engine load side as the coolant temperature becomes lower.

A variable cylinder engine is provided. The engine includes an engine body having a plurality of cylinders, a cooling mechanism for cooling the engine body by using a coolant, and a controller for controlling a temperature of the coolant and changing the number of active cylinders according to an operating state of the engine. The controller reduces the number of active cylinders in a reduced-cylinder operating range set within a partial engine load range, and expands the reduced-cylinder operating range to a higher engine load side as the coolant temperature becomes lower.

A method for detecting coking in the intake tract of an internal combustion engine having direct fuel injection is provided. The internal combustion engine has variable intake valve control. The variable intake valve control makes it possible to change the open time of the intake valves in relation to the crank angle of the crankshaft. In the method, the internal combustion engine is operated in idling mode at an idling rotational speed that is elevated in comparison with the normal idling operation. In order to perform the measurement, the open time of the intake valves is also shifted in an advanced direction. An uneven-running characteristic value of the internal combustion engine that is characteristic of the uneven running of the internal combustion engine is determined, and the presence of coking in the intake tract can be detected on the basis of the uneven-running characteristic value.

A method for detecting coking in the intake tract of an internal combustion engine having direct fuel injection is provided. The internal combustion engine has variable intake valve control. The variable intake valve control makes it possible to change the open time of the intake valves in relation to the crank angle of the crankshaft. In the method, the internal combustion engine is operated in idling mode at an idling rotational speed that is elevated in comparison with the normal idling operation. In order to perform the measurement, the open time of the intake valves is also shifted in an advanced direction. An uneven-running characteristic value of the internal combustion engine that is characteristic of the uneven running of the internal combustion engine is determined, and the presence of coking in the intake tract can be detected on the basis of the uneven-running characteristic value.