A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

A control device for an engine is provided, which includes variable intake and exhaust valve operating mechanisms, a supercharger provided to an intake passage and configured to boost intake air introduced into a cylinder, and a controller. The controller drives the supercharger when the engine operates in a boosted range. The controller controls the variable intake and exhaust valve operating mechanisms so that a valve overlap period during which intake and exhaust valves open simultaneously is formed, when the engine operates in a low-speed boosted range of the boosted range where the engine speed is less than a reference speed. The controller controls the variable exhaust valve operating mechanism so that the open timing of the exhaust valve is more advanced when the engine operates in a high-speed boosted range of the boosted range where the engine speed is greater than or equal to the reference speed.

Systems, apparatus, and methods are disclosed that include a divided exhaust engine with at least one primary EGR cylinder and a plurality of non-primary EGR cylinders. The systems, apparatus and methods control the amount of recirculated exhaust gas in a charge flow in response to EGR fraction deviation conditions.

A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

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 engine control method of a hybrid electric vehicle is provided. The method includes detecting a state of charge (SOC) of a main battery of the hybrid electric vehicle and detecting whether a brake requires operation when the main battery is in a fully-charged state or a charging-limiting state. An engine fuel cut of the hybrid electric vehicle is executed when a request for the engine brake is generated and an engine is operated to maximize an engine load of the hybrid electric vehicle.

When an operation state switches from a first operation region A to a second operation region B, the valve timing of an intake valve and an exhaust valve is switched upon switching of the operation state from the first operation region A to the second operation region B. When the operation state switches from the first operation region A to the second operation region B, the air-fuel ratio is switched after a first predetermined time T1 has elapsed since when the actual valve timing of the intake valve became a second intake valve timing and the actual valve timing of the exhaust valve became a second exhaust valve timing. In this way, it becomes possible to ensure ignition when the operation state switches.

Systems and methods for operating a spark ignition engine that includes a particulate filter in the engine's exhaust system are described. In one example, the spark ignition engine is prevented from exceeding a threshold engine load when the engine is supplying power to an electric machine so that engine emissions may be reduced.

An internal combustion engine includes combustion chambers, each having a controllable intake valve controlling an intake port, a controllable exhaust valve controlling an exhaust port, a piston, and a fuel injector. An intake manifold is connected to the intake port of each chamber. In catalytic converter warm-up mode, each chamber is driven in four-stroke operation including a 720 crank angle degrees cycle, and opens the intake port, starting to open in 90-180 CAD, and fully closes the intake port in 180-270 CAD, opens the exhaust port during the power stroke, starting in 405-495 CAD, opens the intake port during the exhaust stroke, starting in 610-690 CAD, and fully closes the exhaust port during the exhaust stroke in 630-710 CAD. Exhaust gas is forced into the intake manifold by the piston, mixing fuel and exhaust in the intake manifold, and fully closes the intake port in 700 to 720+20 CAD.

The present disclosure relates to a method for operating an internal combustion engine (IO). The method includes generating a pressure pulse in an exhaust gas system of the internal combustion engine (IO). The method also includes supplying exhaust gas from a combustion chamber of a cylinder during an exhaust outlet stroke of the cylinder into an inlet channel of the cylinder by propagating the pressure pulse from the exhaust gas system into the combustion chamber of the cylinder. The method further includes supplying the exhaust gas from the inlet channel of the cylinder into the combustion chamber of the cylinder during an intake stroke of the cylinder. By means of internal residual gas control (residual exhaust gas control), the method permits the exhaust gas temperature to be raised in at low load without negatively influencing the full load performance of the internal combustion engine (IO).