Embodiments for operating an engine with skip fire are provided. In one example, a method comprises during a skip fire mode or during a skip fire mode transition, port injecting a first fuel quantity to a cylinder of an engine, the first fuel quantity based on a first, predicted air charge amount for the cylinder and lean of a desired air-fuel ratio, and direct injecting a second fuel quantity to the cylinder, the second fuel quantity based on the first fuel quantity and a second, calculated air charge amount for the cylinder.

A two-stroke internal combustion engine has a crankcase, a cylinder block defining at least one cylinder, a cylinder, a crankshaft, at least one piston, at least one scavenge port, at least one throttle body for supplying air to an interior of the crankcase, at least one direct fuel injector fluidly communicating with at least one combustion chamber for injecting fuel directly in the at least one combustion chamber; and at least one port fuel injector fluidly communicating with the interior of the crankcase for injecting fuel upstream of the at least one combustion chamber. Methods for controlling an engine having at least one direct fuel injector and at least one port fuel injector are also described.

The present disclosure provides a fuel injection unit for an internal combustion engine. The fuel injection unit includes: a separator that is disposed in an intake port to supply air into a combustion chamber formed in an engine head, and that divides a channel for air into an upper channel and a lower channel; a blade disposed ahead of the separator and opening or closing the upper channel or the lower channel by rotating; and a first injector disposed over the intake port. In particular, when the first injector injects fuel, the blade does not interfere with the fuel.

Methods and systems are provided for adjusting engine operating conditions for reduction of NOx emissions. In one example, immediately after a fuel shut-off event, in response to an oxygen content of an exhaust catalyst being higher than a threshold, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection. By increasing manifold cooling, NOx production may be reduced.

An internal-combustion engine includes: a direct fuel injector directly injecting fuel into a combustion chamber; and a control device. The control device performs: presumption processing that presumes, based on an operating condition of the internal-combustion engine, that a thermoplastic deposit is formed on an injection hole portion of the direct fuel injector; temperature control processing that increases a temperature of the injection hole portion when the thermoplastic deposit is presumed to be formed; and first removal processing that injects the fuel from the direct fuel injector after the temperature control processing.

An internal combustion engine includes a combustion chamber defined by a cylinder bore in a cylinder block, a cylinder head and a piston. A groundless barrier discharge plasma igniter including an electrode is embedded in a casing fabricated from a dielectric material and is disposed in a mounting boss. The groundless barrier discharge plasma igniter has a tip portion that protrudes through an opening in the cylinder head into the combustion chamber. A controller having an electrical ground connection to the cylinder head is configured to apply a high frequency electrical pulse to the groundless barrier discharge plasma igniter. An electrical ground path is formed between the mounting boss and the cylinder head. A plurality of plasma discharge streamers is generated on the casing between the tip portion and the mounting boss when the controller applies the high frequency electrical pulse to the groundless barrier discharge plasma igniter.

A method of operating an internal combustion engine having a plurality of cylinders, the method comprising: operating the engine with at least one of the cylinders of the engine as a dedicated exhaust gas recirculation (EGR) cylinder; mixing exhaust gas expelled from the dedicate EGR cylinder with air in an intake system to provide a mixture of exhaust gas and air; providing a first hydrocarbon fuel and a second hydrocarbon fuel; introducing a charge comprising the first hydrocarbon fuel, the second hydrocarbon fuel and the mixture of exhaust gas and air to the dedicated EGR cylinder; igniting the charge in the dedicated EGR cylinder; expelling exhaust gas from the dedicated EGR cylinder; and recirculating the exhaust gas to the intake system of the engine.

Methods and systems are provided for adjusting engine operating conditions for mitigation of pre-ignition in one or more engine cylinder. In one example, a method may include, in response to indication of pre-ignition, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection, while maintaining engine operation at or around a stoichiometric air-fuel ratio.

Methods and systems are provided for adjusting engine operating conditions for reduction of NOx emissions. In one example, immediately after a fuel shut-off event, in response to an oxygen content of an exhaust catalyst being higher than a threshold, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection. By increasing manifold cooling, NOx production may be reduced.

Methods and systems are provided for adjusting engine operating conditions for mitigation of pre-ignition in one or more engine cylinder. In one example, a method may include, in response to indication of pre-ignition, manifold charge cooling may be increased by increasing the portion of fuel delivered to the engine via manifold injection relative to the portion to fuel delivered via one or more of port and direct injection, while maintaining engine operation at or around a stoichiometric air-fuel ratio.