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, a method may include supplying air to an exhaust system at a location downstream of an emissions control device via the first exhaust manifold, the air not having participated in combustion in the engine, the first exhaust manifold in fluidic communication with a first exhaust valve of a cylinder and an intake manifold, the cylinder including a second exhaust valve in fluidic communication with the second exhaust manifold. The method may further include adjusting an amount of fuel injected to the engine in response to output of a first oxygen sensor, the first oxygen sensor positioned in the exhaust system upstream of the emissions control device.

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, a method may include supplying air to an exhaust system at a location downstream of an emissions control device via the first exhaust manifold, the air not having participated in combustion in the engine, the first exhaust manifold in fluidic communication with a first exhaust valve of a cylinder and an intake manifold, the cylinder including a second exhaust valve in fluidic communication with the second exhaust manifold. The method may further include adjusting an amount of fuel injected to the engine in response to output of a first oxygen sensor, the first oxygen sensor positioned in the exhaust system upstream of the emissions control device.

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 air-fuel control method for the engine system may include flowing air from the intake manifold through a plurality of engine cylinders to a junction of the exhaust passage and a bypass passage in response to a condition, the junction positioned along the exhaust passage between first and second emission control devices. The method may further include flowing exhaust gas to the first emission control device while flowing the air to the junction.

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 air-fuel control method for the engine system may include flowing air from the intake manifold through a plurality of engine cylinders to a junction of the exhaust passage and a bypass passage in response to a condition, the junction positioned along the exhaust passage between first and second emission control devices. The method may further include flowing exhaust gas to the first emission control device while flowing the air to the junction.

An internal combustion engine is described, and includes a method for operating that includes determining an observed carbon monoxide (CO) ratio in an exhaust gas feedstream, determining an observed in-cylinder scavenging based upon the observed CO ratio in the exhaust gas feedstream, and controlling, by a controller, control states for the variable cam phasing system to control opening times of engine intake valves in relation to closing times of engine exhaust valves based upon the observed in-cylinder scavenging.

An internal combustion engine is described, and includes a method for operating that includes determining an observed carbon monoxide (CO) ratio in an exhaust gas feedstream, determining an observed in-cylinder scavenging based upon the observed CO ratio in the exhaust gas feedstream, and controlling, by a controller, control states for the variable cam phasing system to control opening times of engine intake valves in relation to closing times of engine exhaust valves based upon the observed in-cylinder scavenging.

An internal combustion engine including internal cavities slidingly receiving a respective piston to define a respective combustion chamber, at least one inlet port for each internal cavity in fluid communication with the combustion chamber at least during the intake phase and a beginning of the compression phase, at least one exhaust port for each of the internal cavities and in fluid communication with the combustion chamber during the exhaust phase, a plenum for receiving pressurized air, and conduits in fluid communication with the plenum. Each conduit defines a fluid communication between a first respective internal cavity and a second respective internal cavity through the inlet ports. The combustion chamber of the first respective internal cavity undergoes the beginning of the compression phase simultaneously with the combustion chamber of the second respective internal cavity undergoing the beginning of the intake phase.

An internal combustion engine including internal cavities slidingly receiving a respective piston to define a respective combustion chamber, at least one inlet port for each internal cavity in fluid communication with the combustion chamber at least during the intake phase and a beginning of the compression phase, at least one exhaust port for each of the internal cavities and in fluid communication with the combustion chamber during the exhaust phase, a plenum for receiving pressurized air, and conduits in fluid communication with the plenum. Each conduit defines a fluid communication between a first respective internal cavity and a second respective internal cavity through the inlet ports. The combustion chamber of the first respective internal cavity undergoes the beginning of the compression phase simultaneously with the combustion chamber of the second respective internal cavity undergoing the beginning of the intake phase.

An internal combustion engine including internal cavities slidingly receiving a respective piston to define a respective combustion chamber, at least one inlet port for each internal cavity in fluid communication with the combustion chamber at least during the intake phase and a beginning of the compression phase, at least one exhaust port for each of the internal cavities and in fluid communication with the combustion chamber during the exhaust phase, a plenum for receiving pressurized air, and conduits in fluid communication with the plenum. Each conduit defines a fluid communication between a first respective internal cavity and a second respective internal cavity through the inlet ports. The combustion chamber of the first respective internal cavity undergoes the beginning of the compression phase simultaneously with the combustion chamber of the second respective internal cavity undergoing the beginning of the intake phase.

A method of feeding air to an internal combustion engine having at least first and second internal cavities, including: completing the intake phase of the first combustion chamber of the first internal cavity by feeding compressed air into the first combustion chamber until a maximum volume thereof is reached; during a beginning of the compression phase of the first combustion chamber and a simultaneous beginning of the intake phase of the second combustion chamber of the second internal cavity, feeding compressed air from the first combustion chamber into the second combustion chamber; closing a communication between the first and second combustion chambers and completing the intake phase of the second combustion chamber by feeding compressed air into the second combustion chamber until a maximum volume thereof is reached.