Methods and systems are provided to control exhaust energy delivered to a turbine of a turbine-generator coupled to a split exhaust engine system in order to limit turbine over-speed conditions and/or reduce generator vibration or reduce component over-heating conditions. In one example, a method may comprise in response to turbine speed greater than a threshold speed, selectively deactivating a first exhaust valve of one or more cylinders of a first and second cylinder group.

An objective of the present invention is to stabilize the fuel injection amount for each cylinder and to execute fuel injection control accurately in a single-pressure-feed dual-injection type alcohol fuel injection system. An engine includes two injection valves and and a single-pressure-feed dual-injection type fuel supply system. The fuel supply system is configured such that fuel is injected sequentially in two cylinders during the pressure-feed-interval period from the execution of one fuel pressure-feed operation to the execution of the next fuel pressure-feed operation. If the alcohol concentration in the fuel is higher than a predetermined determination value γ at a startup operation time, an ECU executes only a cylinder injection for the first of the two cylinders described above, and executes both an intake passage injection and a cylinder injection for the second cylinder. Thus, even if the fuel pressure decreases due to the fuel injection for the first cylinder, the required fuel injection amount can be reserved for the second cylinder.

A method for operating a compression ignition engine includes forming a combustible mixture by mixing generally homogeneously a first fuel and air and introducing this mixture into the at least one cylinder, compressing the combustible mixture with the piston in a compression stroke, injecting a second fuel to the combustible mixture at an injection-time of the second fuel during the compression stroke but before start of combustion, and continuing the compression stroke until combustion starts at those locations in the at least one cylinder where concentration of the second fuel is highest and/or the temperature of the mixture is the highest. Emission of the cylinder and/or mechanical stress of the cylinder caused by the combustion are monitored, and if emissions and/or mechanical stress are above respective predetermined thresholds, individually for the cylinder, the amount and/or the timing of the second fuel injected, and/or temperature of the cylinder charge is changed.

Engine controllers and control schemes are provided for managing engine state transitions requiring increased compressor pressure ratios in turbocharged engines operating in a cylinder output level modulation mode (e.g., skip fire, multi-level skip fire, or firing level modulation modes). In some circumstances, turbo lag can be mitigated by initially transitioning the engine to an intermediate effective firing density that is higher than both the initial and target effective firing density to increase the flow of gases through the engine and the turbocharger while maintaining a compressor ratio the same as or close to the initial compressor pressure ratio. After reaching a point where the desired torque is actually generated at the intermediate effective firing density, the operational effective firing density is gradually reduced to the target effective firing density while increasing the operational compressor pressure ratio to the target compressor ratio.

An internal combustion engine is provided with a plurality of cylinders, air intake valves provided to each of the cylinders, and a variable valve actuation mechanism for varying the valve actuation of the air intake valves. A motor drives the variable valve actuation mechanism. A motor controller controls the motor. The internal combustion engine is capable of operating in a cylinder deactivation mode, in which the air intake valves of some of the cylinders are kept shut. When the internal combustion engine is reactivated from the cylinder deactivation mode, the motor controller executes an air intake amount correction process, in which the opening duration of the air intake valves is temporarily increased, thereby increasing the amount of air taken in by operating cylinder for which the air intake valves have been opened or closed even during the cylinder deactivation mode.

A controller and a control method for internal combustion engine, and a memory medium are provided. A port injection ratio is changed according to an engine operating state of the internal combustion engine. The port injection ratio is a ratio of a port injection amount that is an amount of fuel injected by port injection valves to an amount of fuel supplied to cylinders from the port injection valves and direct injection valves. An injection reducing process causes a fuel injection amount in a reduced-injection cylinder to be smaller than a fuel injection amount in other cylinders. An increase limiting process limits increases in an adhered fuel amount in intake ports by regulating the port injection ratio during execution of the injection reducing process.

A system for diagnosing engine braking performance of an engine comprising a plurality of cylinders comprises an exhaust manifold pressure sensor configured to detect an exhaust manifold pressure corresponding to exhaust gas emitted from a plurality of cylinders. A controller is configured to determine an exhaust manifold pressure value corresponding to at least one cylinder of the plurality of cylinders that is being used for engine braking, from an exhaust manifold pressure sensor signal received from the exhaust manifold pressure sensor. The controller is also configured to determine an engine braking value based on the exhaust manifold pressure value.

Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

Methods, systems, and devices for managing motor torque smoothing for internal combustion engine cylinder recharging events are described herein. An engine controller in a vehicle for managing motor torque smoothing for internal combustion engine cylinder recharging events may be configured to operate the internal combustion engine at a firing fraction that is less than a value of 1.0, wherein one or more cylinders are not designated to be fired, determine a recharge event time period where a particular one of the cylinders that have not been designated to be fired is recharged, identify a disruption quantity of torque during the recharging event time period, and actuate an additional motor to initiate a supplemental quantity of torque during the recharge event time period based on the disruption quantity of torque.