A method for operating an internal combustion engine is provided. The method includes during a first operating condition, operating two primary cylinders and two secondary cylinders to perform combustion, the two primary and secondary cylinders arranged in an inline configuration, the two primary cylinder adjacent to one another, the two secondary cylinders adjacent to one another, and the secondary cylinders positioned 175°-185° out of phase relative to the two primary cylinders and during a second operating condition, selectively deactivating the two secondary cylinders to perform combustion in only the two primary cylinders.

An engine braking system includes engine braking actuators for adjusting exhaust valve timings to engine braking timings in a cylinder-number braking mode. The system further includes an engine braking controller coupled to a control switch that produces a request indicating a requested cylinder-number braking mode. The engine braking controller is structured to transition exhaust valves to the engine braking timings, determine a control term to adjust intake air pressure for varying a braking power of the engine, and to adjust geometry of an exhaust turbine based on the control term. An adjusted speed of a compressor rotated by the exhaust turbine provides a change to intake air pressure that adjusts the braking power of the engine. Different levels of braking power are provided within different cylinder-number braking modes.

A method for jumping cylinder deactivation (“CDA”) modes to avoid a primary powertrain resonant frequency in a six-cylinder diesel engine-powered machine comprises operating an engine between an idled condition and a first engine speed limit in one of a two-cylinder CDA mode or a four-cylinder CDA mode. The method operates the engine between the first engine speed limit and a second engine speed limit in a three-cylinder CDA mode. The first engine speed limit is an engine speed below which the two-cylinder or four-cylinder CDA mode causes the machine to operate below a primary powertrain resonant frequency and also above which the three-cylinder CDA mode causes the machine to operate above the primary powertrain resonant frequency, thus avoiding the primary powertrain resonant frequency during operation. A second engine speed limit can be used to select a CDA mode that causes the machine to operate above the primary powertrain resonant frequency.

An engine brake controller may obtain a performance characteristic of an engine. The engine brake controller may determine, based on the performance characteristic of the engine, that engine braking is enabled to control the engine. The engine brake controller may monitor a set of operating parameters of the engine. The engine brake controller may determine that operating values of the set of operating parameters satisfy corresponding thresholds of the set of operating parameters. The engine brake controller may determine, based on the operating values satisfying the corresponding thresholds, an engine braking configuration associated with activating engine braking of a set of cylinders of the engine. The set of cylinders may be a proper subset of a total quantity of cylinders of the engine. The engine brake controller may cause the engine braking to be applied to the set of cylinders to increase a temperature of exhaust gas from the engine.

Methods and systems are provided for improving the performance of a variable displacement engine. Split injection and spark retard may be used in active cylinders during a VDE mode to heat an exhaust catalyst and extend the duration of VDE mode operation. Split injection and spark retard may also be used in reactivated cylinders at a time of cylinder reactivation to improve restart combustion stability.

The invention has an object to control an EGR amount accurately in transient time. An ECU switches EGR control to the one-valve EGR control and the both-valve EGR control based on a request EGR amount. When the EGR control is switched to the one-valve EGR control from the both-valve EGR control, an EGR valve of one bank is closed first. Next, during a time period until an opening degree restriction time period elapses after the EGR valve is closed, an opening degree of an EGR valve of the other bank is restricted to be smaller than a one-valve target opening degree. Subsequently, when the opening degree restriction time period elapses, restriction of the opening degree of the EGR valve is cancelled, and the opening degree of the EGR valve is changes to the one-valve target opening degree.

Methods and systems for operating an engine that includes adjustable poppet valve timing and an exhaust gas recirculation valve are described. In one example, the exhaust gas recirculation valve is opened and the timing of the poppet valves is retarded so that an amount of fresh air that is pumped by the engine to an after treatment device may be reduced.

Systems and methods for controlling fuel factions delivered to different cylinders are provided. In one example, a controller is configured to, during a single engine cycle and responsive to a first condition, deliver a lower fraction of a first fuel into a donor cylinder in comparison to a fraction of the first fuel being injected into a non-donor cylinder and deliver a higher fraction of a second fuel into the donor cylinder in comparison to a fraction of the second fuel being injected into the non-donor cylinder.

A method for operating a system having a plurality of internal combustion engines coupled together such that then outputs are drawn off by a common load, a downstream individual exhaust gas aftertreatment device, in which the exhaust gas of a particular engine undergoes an individual exhaust gas aftertreatment, positioned downstream of each engine, or a common exhaust gas aftertreatment device, in which the exhaust gas undergoes a common exhaust gas aftertreatment, positioned downstream of to the engine. To regenerate an exhaust gas aftertreatment device, the drive output of one engine is reduced, the temperature of the exhaust gas is increased, and the drive output of a second engine is increased such that the drive output reduction is at least partially compensated for.

Internal combustion engine having cam actuated valves that can be controlled to facilitate the use of different air charge levels in different cylinders or sets of cylinders are described. In one aspect a first set of cylinders is operated in a skip fire manner in which the corresponding cylinders are deactivated during skipped working cycles. Cam actuated intake valves associated with a second set of cylinders are operated differently so that the air charge in the cylinders in the second set is different than the air charge in fired cylinders subject to the skip fire control. According to another aspect, an engine having cam actuated intake valves is operated in a dynamic firing level modulation mode. During the dynamic firing level modulation operation, the cam actuated intake valves are controlled in at least two different manners to such that different cylinder working cycles have different air charges.