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.

A system and method for dissipating vehicle under hood heat accumulated during stationary engine operation at high load or RPM and/or under high temperature ambient conditions is installed in a vehicle having an engine positioned within an engine compartment, and a cooling fan selectively driven by way of a fan clutch. The system includes a controller connected to the engine and to the fan clutch. The controller determines whether the period of stationary engine operation occurs at or above a threshold engine load or RPM, at or above a threshold engine operating temperature, at or above a threshold ambient temperature, and/or for or longer than a threshold stationary engine operation duration. If so, the at least one controller increases a low idle set point of the engine and commands the fan clutch to engage or remain engaged for a cool-down period following the period of stationary engine operation.

Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, values of an engine spark to engine torque relationship are adjusted to improve engine torque control. The engine is subsequently operated responsive to adjusted values of the engine spark to engine torque relationship.

Methods for determining an irregular fuel request (IFR) for vehicle engines coupled to driveshafts via clutched transmissions are provided and include: determining an idle condition of the engine, generating one or more fuel requests during the idle condition, and determining an IFR based on a clutch control parameter and a fuel request generated during the idle condition. The idle condition of the engine is determined based on a vehicle speed and an engine speed if the vehicle speed and engine speed are below respective thresholds. An IFR is determined if a fuel request falls outside a range, and/or if the clutch control parameter is such that the clutch does not substantially impart load to the engine. The idle fuel request range is determined based on a combustion mode of the engine and/or a gear state of the transmission. The method further includes implementing a control action after determining an IFR.

A method for operating an idling control device for a motor vehicle. The idling control device specifies a total setpoint torque including a setpoint torque of an electric motor and a setpoint torque of an internal combustion engine which interacts with the electric motor, and sets the setpoint torques by respective control paths. In a first operating mode the idling control device sets a requested total setpoint torque only via the control path of the internal combustion engine by at least one control intervention, and in a second operating mode the idling control device sets the requested total setpoint torque by at least one control intervention via the control path of the internal combustion engine and by at least one control intervention via the control path of the electric motor. The control interventions via the control path of the internal combustion engine consist of at least one predetermined slow control intervention, and the control interventions in the control path of the electric motor consist of at least one predetermined fast control intervention, which intervenes with a higher rate of change over time than the at least one predetermined slow control intervention.

A system and method for dissipating vehicle under hood heat accumulated during stationary engine operation at high load or RPM and/or under high temperature ambient conditions is installed in a vehicle having an engine positioned within an engine compartment, and a cooling fan selectively driven by way of a fan clutch. The system includes a controller connected to the engine and to the fan clutch. The controller determines whether the period of stationary engine operation occurs at or above a threshold engine load or RPM, at or above a threshold engine operating temperature, at or above a threshold ambient temperature, and/or for or longer than a threshold stationary engine operation duration. If so, the at least one controller increases a low idle set point of the engine and commands the fan clutch to engage or remain engaged for a cool-down period following the period of stationary engine operation.

A method and apparatus controlling the fuel-to-air ratio of a fuel and air mixture supplied to an operating engine includes the steps of determining a first engine speed before enleanment of the mixture, determining a second engine speed near or at the end of a period of enleanment of the mixture, and after ending the enleanment, determining whether the engine speed recovers within a predetermined range of the first engine speed and if so determining a delta speed difference between the first and second speeds and using this delta speed difference as a factor in determining a change in the fuel-to-air ratio of the fuel mixture supplied to the engine.

A vehicular breather device through which an inside space of a casing accommodating a power transmitting system of a vehicle is open to an outside atmosphere outside the casing, the vehicular breather device including: a second shaft rotated with a rotary motion of a first shaft of the power transmitting system transmitted thereto through a power transmitting member, the second shaft being accommodated within the casing, having a breather chamber formed therethrough, and being disposed so as not to contribute to transmission of a vehicle drive force through the power transmitting system; and a breather disposed so as to extend through a communication hole formed through the casing, for communication between the breather chamber and the outside atmosphere outside the casing.

Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, values of an engine spark to engine torque relationship are adjusted to improve engine torque control. The engine is subsequently operated responsive to adjusted values of the engine spark to engine torque relationship.

A system according to the principles of the present disclosure includes an engine stall module and an actuator control module. The engine stall module identifies a potential engine stall based on a speed of an engine and a rate of change in the engine speed. The actuator control module selectively adjusts an actuator of a powertrain system to prevent the engine from stalling when a potential engine stall is identified.