Systems and methods for operating an engine that may selectively enter and exit a fuel cut-off mode are described. In one example, the method holds the engine in the fuel cut-off mode even though a propulsive effort pedal is applied. An electric machine may provide torque to a vehicle driveline while the engine is in the fuel cut-off mode.

A reduction method for a catalytic converter in an exhaust system of an internal combustion engine for reducing the oxygen content in the catalytic converter, in particular after an overrun fuel cutoff mode of the internal combustion engine, the method including first injection of fuel into a first cylinder, the first injection taking place after an ignition point in time of a compression stroke of a first working cycle of the cylinder and including an introduction of the injected fuel from the cylinder into the catalytic converter during an exhaust stroke of the first cylinder.

A vehicle controller includes processing circuitry. The processing circuitry is configured to perform an intermittent stop of an engine in accordance with a traveling state of a vehicle, cause the engine to restart by self-sustaining resumption when restart of the engine is requested in a state in which the engine is rotating during the intermittent stop, and perform a retarded injection control that retards, in a combustion cycle of the engine, a starting time of a first fuel injection at the time of the restart of the engine by the self-sustaining resumption as compared to a starting time of a second fuel injection.

An internal combustion engine control apparatus including a microprocessor. The microprocessor is configured to perform controlling a fuel injector so as to inject a fuel of a target injection amount by dividing into a plurality of times at a predetermined time interval in an area from a first crank angle at which an intake stroke is started to a second crank angle at which a compression stroke is ended, and setting the predetermined time interval. The microprocessor is configured to perform the setting including setting the predetermined time interval so that a spray length from a tip of the fuel injector to a tip of a spray of the fuel injected from the fuel injector becomes shorter than the spray length when the fuel of the target injection amount is injected at once in the area by a predetermined rate.

A control apparatus of an internal combustion engine is provided. The internal combustion engine includes a port injection valve that injects fuel into an intake-air port, and a cylinder injection valve that injects fuel into a cylinder. The control apparatus includes an electronic control unit that controls the port injection valve and the cylinder injection valve such that when returning from a fuel cut, a value of a port increase amount correction, which is a fuel increase amount correction in which a fuel amount is decreased with a lapse of time during a port injection, differs from a value of a cylinder increase amount correction, which is a fuel increase amount correction in which a fuel amount is decreased with a lapse of time during a cylinder injection.

Methods and systems for operating an engine that includes adjustable poppet valve timing and an exhaust gas recirculation valve are described. In one example, the exhaust gas recirculation valve is opened and the timing of the poppet valves is retarded so that an amount of fresh air that is pumped by the engine to an after treatment device may be reduced.

An internal combustion engine control apparatus including an electronic control unit having a microprocessor and a memory. The microprocessor is configured to perform switching an injection mode between a first injection mode in which the fuel is injected in a range including an intake stroke and a compression stroke of an internal combustion engine and a second injection mode in which the fuel is injected in the range so that an injection frequency in the compression stroke in the second injection mode is greater than an injection frequency in the compression stroke in the first injection mode; and determining whether the injection mode needs to be switched based on an ignition timing of the ignitor.

A fuel injection timing is made later and/or a fuel injection amount is made larger in a target cylinder to be subjected to explosive combustion subsequently, when a required rotation time that is a time required for rotation of an output shaft by a predetermined rotational angle is equal to or longer than a time threshold than when the required rotation time is shorter than the time threshold, at the time of predetermined startup control in which an engine and a clutch are controlled such that fuel injection and ignition in the engine are resumed from a state where the supply of fuel to the engine is cut off and the clutch is released and that the clutch is then engaged.

To keep medium purification efficiency at a high level and prevent deterioration of emission performance. An aspect of the present invention includes: a downstream equivalence ratio calculation unit that calculates a catalyst downstream exhaust gas equivalence ratio by using a catalyst statistical model that receives at least a detection value of an air-fuel ratio sensor on an upstream side of a catalyst and outputs a catalyst downstream exhaust gas equivalence ratio; an oxygen output calculation unit that calculates an output value of an oxygen sensor by using an oxygen sensor statistical model that receives the catalyst downstream exhaust gas equivalence ratio and outputs an output value of the oxygen sensor on the downstream side of the catalyst; a downstream equivalence ratio correction unit that corrects the catalyst downstream exhaust gas equivalence ratio calculated by the downstream equivalence ratio calculation unit based on a calculation result of the oxygen output calculation unit and the detection value of the oxygen sensor; and an air-fuel ratio control unit that controls an air-fuel ratio of an air-fuel mixture of an internal combustion engine based on the corrected catalyst downstream exhaust gas equivalence ratio and air-fuel ratio target value.

A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method adjusts an estimate of an exhaust gas oxygen sensor delay time based on a fuel injection ramping time. The fuel injection ramping time compensates for fuel that is injected to the engine while the engine enters or exits a fuel cut-off mode.