Methods and systems are provided for protecting an exhaust catalyst from degradation during a DFSO event. Exit from DFSO due to pedal input received from an operator with a jittery foot is averted by filtering the pedal input differently when operating in a DFSO mode as compared to when operating out of the DFSO mode. Exit from DFSO is confirmed after receiving a higher than threshold pedal position input for a sustained period of time, or when an integrated fuel injection amount exceeds a threshold amount.

Controllers and methods for managing transitions into and/or out of a cylinder cut off mode are described. In some embodiments, a skip fire based transition into a cylinder cut off mode is used in which the fraction of working cycles that are fired is gradually reduced to a threshold firing fraction. Once the threshold firing fraction has been reached, all of the working chambers are deactivated.

Aspects of the present invention relate to a controller (104) and method (400) for controlling operation of an internal combustion engine (101). The controller (104) is configured to: receive a first request signal indicative of a request to stop fuel being supplied to the engine (101), and cause an intake valve (301) of a cylinder (103) of the internal combustion engine (101) to remain closed during the current revolution of the internal combustion engine (101) and revolutions of the internal combustion engine (101) immediately following the current revolution of the internal combustion engine (101) in dependence on at least one of: the intake valve (301) being closed at the time of receiving the first request signal; or a next opening of the intake valve having not been scheduled. The controller (104) is also configured to cause injection of fuel into the cylinder (103) and subsequently cause the intake valve (301) to remain closed during revolutions of the internal combustion engine (101) immediately following a next closing of the intake valve (301), in dependence on at least one of: the intake valve (301) being open at the time of receiving the first request signal; and a next opening of the intake valve (301) having already been scheduled at the time of receiving the first request signal and said next opening of the intake valve (301) is to be performed.

Methods and systems are provided for engine braking in a vehicle. In one example, a method may include, in response to an engine braking request: deactivating fueling to at least one engine cylinder, decreasing an effective flow area of a turbine inlet of a variable geometry turbocharger (VGT), and adjusting an intake valve of the at least one engine cylinder based on a requested braking torque of the engine braking request and the effective flow area of the turbine inlet. In this way, increased exhaust backpressure may be generated to increase engine pumping losses while the intake valve adjustment increases in-cylinder pumping losses, thereby increasing an amount of engine braking torque.

The invention relates to an internal combustion engine with an air intake system and an exhaust system is embodied as an internal combustion engine, in particular a gasoline engine, that is charged by means of an exhaust gas turbocharger. At least one three-way catalytic converter is arranged in the exhaust system of the internal combustion engine. Furthermore, a low-pressure exhaust gas recirculation system is provided that connects the exhaust system downstream from a turbine of the exhaust gas turbocharger and upstream from the at least one three-way catalytic converter to the air intake system upstream from a compressor of the exhaust gas turbocharger. The invention further relates to a method for exhaust aftertreatment of such an internal combustion engine.

Aspects of the present invention relate to a control system (104) for controlling operation of an internal combustion engine (102), an internal combustion engine (102), a vehicle (100), a method (600) and a non-transitory computer readable medium (202). The control system (104), comprises at least one controller. The control system (104) and being configured to: receive a first request signal indicative of first torque demand; determine a schedule defining an opening timing of the intake valve (402) and a closing timing of the intake valve (402) of a cylinder (103) of the internal combustion engine (102) in dependence on the first torque demand; and cause the intake valve (402) to open in accordance with the schedule. The control system (104) is also configured to, during a period in which the intake valve (402) is open: receive a second torque request signal indicative of a second torque demand different to the first torque demand; determine an updated schedule defining an updated closing timing of the intake valve (402) in dependence on the second torque demand; and cause the intake valve (402) to close in accordance with the updated schedule.

Aspects of the present invention relate to a controller (104) and method (400) for controlling operation of an internal combustion engine (101). The controller (104) is configured to: receive a first request signal indicative of a request to stop fuel being supplied to the engine (101), and cause an intake valve (301) of a cylinder (103) of the internal combustion engine (101) to remain closed during the current revolution of the internal combustion engine (101) and revolutions of the internal combustion engine (101) immediately following the current revolution of the internal combustion engine (101) in dependence on at least one of: the intake valve (301) being closed at the time of receiving the first request signal; or a next opening of the intake valve having not been scheduled. The controller (104) is also configured to cause injection of fuel into the cylinder (103) and subsequently cause the intake valve (301) to remain closed during revolutions of the internal combustion engine (101) immediately following a next closing of the intake valve (301), in dependence on at least one of: the intake valve (301) being open at the time of receiving the first request signal; and a next opening of the intake valve (301) having already been scheduled at the time of receiving the first request signal and said next opening of the intake valve (301) is to be performed.

A method for controlling engine braking in a vehicle comprises: determining a position of a throttle operator; determining a speed of the vehicle; and determining an engine braking mode selected. In response to the position of the throttle operator being a fully released position and the selected braking mode being a first engine braking mode: controlling an engine and a position of a throttle valve according to the first engine braking mode for applying a first level of engine braking. In response to the position of the throttle operator being the fully released position and the selected braking mode being the second engine braking mode: controlling the engine and the position of the throttle valve according to the second engine braking mode based at least on the speed of the vehicle for applying a second level of engine braking. A vehicle implementing the method is also disclosed.

Aspects of the present invention relate to a controller for controlling operation of an internal combustion engine, a control system, an internal combustion engine, a vehicle, a method and a non-transitory computer readable medium. The controller is configured to, during fuel cut, cause opening of an intake valve of a cylinder of the internal combustion engine to enable air having a mass to enter the cylinder. The mass is below a first range of masses which enable the internal combustion engine to provide combustion torque.

Methods are provided for engines. In one example method, at higher engine load, cool compressed air is drawn into an engine via an air intake passage, and at lower engine load, ambient air is drawn into the engine via a duct while retaining cooled compressed air in the air intake passage. The compressed air may be released from the air intake passage based on heat transferred to the compressed air during the lower engine load, in at least one example.