Various methods and systems are provided for a multi-fuel capable engine. The system includes a liquid fuel system to deliver liquid fuel to an engine, a gaseous fuel system to deliver gaseous fuel to the engine, and a control system. The control system can control and test the liquid and gaseous fuel systems.

Methods and systems are provided for a diagnostic routine of a variable displacement engine (VDE) of a vehicle to detect non-deactivated valves of deactivated cylinders due to a degraded valve deactivation mechanism. In one example, a method comprises, during operation of the VDE with one or more cylinders of the VDE deactivated, calculating a variation in a fast-sampled signal outputted by one or more exhaust gas oxygen (EGO) sensors of the VDE over a plurality of engine cycles; determining that the variation is greater than the threshold variation; and in response, indicating that valves of the one or more cylinders are not deactivated. A second method comprises estimating a throttle air flow rate and an engine air flow rate of the VDE; and indicating non-deactivated valves of one or more deactivated cylinders if the throttle air flow rate exceeds the engine air flow rate by a threshold.

The present invention relates to a method for operating an internal combustion engine provided as a medium-speed gas engine or dual fuel engine in a gas fuel mode. The method comprises the step of directly injecting a gas fuel into a combustion chamber of the engine at a maximum injection pressure that is lower than a compression-end pressure of the engine.

Methods and controllers for controlling engine speed to reduce NVH that occurs in conjunction with transmission shifts are described. In some embodiments, when a transmission shift to a target gear is expected, a target engine speed appropriate for the target gear is first determined. A target rate of change of the engine speed is calculated from the initial engine speed and target engine speed in conjunction with a target transition time. A target torque is then calculated from the target rate of change of engine speed. A target firing fraction or induction ratio are determined that are desired for use with the target engine speed based on the target torque. The transition to the target engine speed and target firing fraction or induction ratio are completed before the gear shift is completed. The described approaches are well suited for use during skip fire or other cylinder output level modulation operation of the engine.

An internal combustion engine has one or more combustion chambers defined by one of more cylinders, corresponding pistons, and a cylinder head. A crankshaft is operatively connected to the pistons and to an electric turning machine. To start the engine, the electric turning machine rotates the crankshaft in a first direction toward a reversal point corresponding to a local maximum drag torque of the internal combustion engine, this rotation being made without rotating the crankshaft beyond the reversal point. The electric turning machine then rotates the crankshaft in a second direction opposite from the first direction, a momentum impressed on the crankshaft by compression obtained when rotating in the first direction increasing a speed of the crankshaft in the second direction. Thereafter, fuel is injected in one of the combustion chambers in which the corresponding piston first reaches a top dead center position and the fuel is ignited.

Methods and systems are provided for a vehicle engine having a pre-chamber ignition system. In one example, a method may include adjusting one or more of an air injection amount and a fuel injection amount to a pre-chamber of an engine based on an air injection offset and a fuel injection offset learned while discontinuing fueling to cylinders of the engine and reducing air flow through the engine. In this way, air and fuel may be more accurately provided to the pre-chamber, thereby decreasing an occurrence of pre-chamber misfire.

A method, for an internal combustion engine including an intake camshaft equipped with a variable intake valve timing device including an intake timing actuator and an exhaust camshaft equipped with a variable exhaust valve timing device including an exhaust timing actuator, of detecting inverted connection of the intake timing actuator with the exhaust timing actuator, including: measuring the angular position of the intake camshaft and the angular position of the exhaust camshaft; commanding one of the two timing actuators according to a setpoint and keeping the other of the two timing actuators immobile; measuring the angular positions of the intake camshaft and of the exhaust camshaft; and comparing: if the angular position of the camshaft corresponding to the timing actuator that's been commanded has not been modified, and if the angular position of the camshaft corresponding to the immobile timing actuator has been modified, inverted connection can be diagnosed.

A turbine fracturing system and a controlling method thereof, a controlling apparatus and a storage medium are provided. The turbine fracturing system includes: N turbine fracturing apparatuses, wherein each of the N turbine fracturing apparatuses comprises a turbine engine, and N is an integer greater than or equal to 2; a fuel gas supply apparatus connected to the N turbine engines, wherein the fuel gas supply apparatus is configured to supply fuel gas and distribute the fuel gas to the N turbine engines as gaseous fuel; and a fuel liquid supply apparatus connected to at least one of the N turbine engines and configured to supply liquid fuel to at least one of the N turbine engines in a case that at least one of a flow rate and a pressure of the fuel gas decreases.

A CPU stops combustion control of Cylinder #1 in order to perform a regeneration process of a GPF and performs a regeneration process of causing an air-fuel ratio of an air-fuel mixture in Cylinders #2 to #4 to be richer. When it is determined that a misfire has occurred because a misfire rate when the regeneration process is not being performed is equal to or greater than a predetermined value, the CPU determines that an internal combustion engine has returned to a normal state based on the premise that the misfire rate when the regeneration process is not being performed decreases.

Methods and systems are provided for reverse purging of a fuel vapor canister of an engine. In one example, a method may include heating a fuel vapor canister, sealing a fuel tank in order to generate a vacuum in the fuel tank, and in response to the pressure in the fuel tank reaching a target vacuum, initiating reverse purging of the fuel vapor canister.