Methods and systems are provided for adjusting amount of directly injected fuel scavenged via a second exhaust manifold of a split exhaust engine system. In one example, a method may include adjusting a start of injection of a fuel direct injection into an engine cylinder, the cylinder including a first exhaust valve coupled to a first exhaust manifold and a second exhaust valve coupled to a second exhaust manifold, the second exhaust manifold coupled to an intake of the engine, based on a closing timing of the second exhaust valve and dependent on an operating condition, and adjusting a position of a bypass valve of the second exhaust manifold based on the adjusted start of injection. In this way, the amount of scavenged fuel may be increased or decreased based on the operating condition.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, an amount of opening overlap between a plurality of intake valves and a first set of exhaust valves coupled to the first exhaust manifold may be adjusted responsive to a transition from an estimated combustion air-fuel content to a leaner air-fuel content of the blowthrough air on a cylinder to cylinder basis. As one example, the transition may be determined from an output of an oxygen sensor positioned within the first exhaust manifold or an exhaust runner of each of the first set of exhaust valves.

The present disclosure relates to a method for braking of an internal combustion engine, in particular a four-stroke internal combustion engine. The method involves a partial opening of at least one gas discharge valve of at least one cylinder of the internal combustion engine during a compression stroke of the internal combustion engine. The method involves a holding of a partial opening of the at least one gas discharge valve during an expansion stroke of the internal combustion engine following the compression stroke and during an exhaust stroke of the internal combustion engine following the expansion stroke. The method involves a closing of the partly opened at least one gas discharge valve at the end of the exhaust stroke or during an intake stroke of the internal combustion engine following the exhaust stroke.

Methods and systems are provided for determining a dilution of recirculated gases, including blowthrough air, combusted exhaust gas, and fuel vapor, in a split exhaust engine. In one example, the dilution rate may be calculated using a feedforward model that includes determining a pressure differential across a region in an intake passage, mapped engine parameters such as gas temperature, and exhaust valve timing. Engine operations such as spark advance and fuel injection may be adjusted according to the modeled rate to reduce engine knock and improve combustion efficiency.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, an intake valve timing, exhaust valve timing of a first set of exhaust valves coupled to the first exhaust manifold, and a position of an exhaust gas recirculation (EGR) valve in an EGR passage may be adjusted in coordination with one another in response to a condition at a compressor. The EGR passage may be coupled between the intake passage, upstream of the compressor, and the first exhaust manifold.

The invention relates to a method for assisted upshifting in a gear change of a transmission connected to a combustion engine. The method comprises the initiation of an upshifting process. The method comprises the reduction of an engine speed of the combustion engine by switching to an engine-braking mode, wherein a variable valve gear, in particular a trip cam system, of the combustion engine serves for switching to the engine-braking mode. Alternatively or in addition, in the engine-braking mode a first exhaust valve of the combustion engine is at first kept closed during the compression stroke and/or during the exhaust stroke for the compression of air and is opened before reaching a top dead centre of a piston movement for decompression of the compressed air.

A method is provided for monitoring the operation of intake valves of an internal combustion engine, where at least one or more cylinders of the engine have more than one intake valve, and adapted to operate in different modes where at least one of the intake valves for a particular cylinder can be selectively activated, or deactivated so as not to open during a firing sequence for the cylinder. The method includes a) monitoring the intake manifold air pressure; b) during a time window with respect to the intake phase for said respective cylinder, determining the condition of whether the manifold pressure drops by a threshold or to a particular threshold level; and c) determining the functionality of the intake valves dependent on the outcome of step b).

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, each of a first valve positioned in an exhaust gas recirculation (EGR) passage, the EGR passage coupled between the intake passage and the first exhaust manifold coupled to a first set of cylinder exhaust valves, and a second valve positioned in a flow passage coupled between the first exhaust manifold and the exhaust passage may be adjusted based on a measured pressure in the first exhaust manifold.

A control system of a Miller cycle engine includes an ECU. The ECU executes an early closing Miller cycle operating mode in which a variable valve mechanism is controlled to close an intake valve before an intake bottom dead center. The ECU executes a decompression mode in which the variable valve mechanism is controlled to close the intake valve at a point later than the intake BDC, when the engine is started. The electronic control unit executes the early closing Miller cycle operating mode after completion of the decompression mode. A later closing amount of the intake valve relative to the intake BDC, for use in the decompression mode, is larger than an early closing amount of the intake valve relative to the intake BDC when the closing timing of the intake valve is most advanced.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, each of a first valve positioned in an exhaust gas recirculation (EGR) passage, the EGR passage coupled between the intake passage and the first exhaust manifold coupled to a first set of cylinder exhaust valves, and a second valve positioned in a flow passage coupled between the first exhaust manifold and the exhaust passage may be adjusted based on a measured pressure in the first exhaust manifold.