An internal combustion engine control apparatus is configured to control an internal combustion engine including a piston reciprocating in a cylinder and a fuel injector arranged to inject a fuel into a combustion chamber facing the piston in the cylinder. The internal combustion engine control apparatus includes an electronic control unit having a microprocessor and a memory. The microprocessor is configured to perform controlling the fuel injector so as to inject the fuel in an injectable 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 an injection frequency of the fuel injected by the fuel injector in the injectable area. The microprocessor is configured to perform the setting including setting the injection frequency between once and four times.

A fuel injection valve is controlled by setting a required injection amount using a required load factor of an engine and a purge correction amount. A purge control valve is controlled using a driving duty based on a required purge ratio when a purge of supplying the evaporated fuel gas to an intake pipe is being executed. During execution of the purge, the purge concentration-related value is learned based on an air-fuel ratio deviation that is a deviation of an air-fuel ratio from a required air-fuel ratio. The certainty of the purge concentration-related value is estimated using a first counter that reflects a number of times of learning of the purge concentration-related value during a first purge and that does not reflect a number of times of learning of the purge concentration-related value during a second purge.

A fuel injection valve is controlled by setting a required injection amount using a required load factor of an engine and a purge correction amount. A purge control valve is controlled using a driving duty based on a required purge ratio when a purge of supplying the evaporated fuel gas to an intake pipe is being executed. During execution of the purge, the purge concentration-related value is learned based on an air-fuel ratio deviation that is a deviation of an air-fuel ratio from a required air-fuel ratio. The certainty of the purge concentration-related value is estimated using a first counter that reflects a number of times of learning of the purge concentration-related value during a first purge and that does not reflect a number of times of learning of the purge concentration-related value during a second purge.

Various methods and systems are provided for dynamically assigning cylinders to cylinder sets in engines having two or more cylinder banks, wherein each cylinder bank is fed intake air by a separate intake manifold, and wherein each cylinder bank includes a separate exhaust manifold. In one example, the current disclosure teaches comparing engine operating conditions against a plurality of predetermined override conditions, and responding to the engine operating conditions matching a predetermined override condition of the plurality of predetermined override conditions by reassigning at least a first cylinder of a first cylinder bank from a first cylinder set to a second cylinder set, and adjusting an operating parameter of the second cylinder set and first cylinder set based on the override condition. In this way, cylinders may be dynamically assigned to cylinder sets based, from a default cylinder set, based on occurrence of predetermined override conditions.

The method includes the following features. A first pressure upstream of a throttle is received. A temperature upstream of the throttle is received. A second pressure within an intake manifold is received. An engine speed is received. An air flow is estimated based on the received first pressure, the received temperature, the received second pressure, and the received engine speed. Estimating the air flow includes determining one or more models to use for calculating air flow based on the received first pressure and the received second pressure. The models include a throttle flow model, a port flow model, or both.

An internal combustion engine control apparatus including a rotational speed sensor detecting a rotational speed of an internal combustion engine, an intake air amount sensor detecting an amount of an intake air supplied into a combustion chamber, a command detector detecting a command of a deceleration of a vehicle on which the internal combustion engine is mounted or a torque down of the internal combustion engine, and a microprocessor. The microprocessor is configured to perform: determining whether a retard condition of an ignition timing is satisfied based on a value detected by the rotational speed sensor or the intake air amount sensor when the command is detected by the command detector, and controlling an ignition part so as to perform an ignition-timing retard control to delay the ignition timing of the ignition part when it is determined that the retard condition is satisfied.

A first pressure upstream of a throttle is received. A temperature upstream of the throttle is received. A throttle position is received. A second pressure at a convergent end of a convergent nozzle positioned downstream of the throttle is received. An air flow is estimated based on the received first pressure, the received temperature, the received throttle position, and the received second pressure, wherein estimating the air flow includes determining one or more models to use for calculating air flow based on the throttle position, the models including a throttle flow model, a convergent nozzle flow model, or both.

A four-stroke internal combustion engine comprising an inlet cam configured to open and close an inlet valve, a No. 1 exhaust cam configured to open and close an exhaust valve, a No. 2 exhaust cam configured to open and close the same exhaust valve, wherein the No. 2 exhaust cam is angularly adjustable relative to the No. 1 exhaust cam in response to input from an operator, so that the No. 2 exhaust cam is able to be selectively engaged; wherein the No. 1 exhaust cam is configured to open and close the exhaust valve during the compression stroke, so that a selected quantity of air drawn in during the intake stroke is expelled during the compression stroke; and wherein the No. 2 exhaust cam is configured to optionally close the exhaust valve when engaged.

An engine system including a fuel system control arrangement includes an internal combustion engine including an exhaust line, one or more cylinders, and one or more fuel injectors corresponding to the one or more cylinders, means for determining fresh air mass flow into an intake to the engine, a nitrogen oxide (NOx) sensor in the exhaust line, and a controller configured to determine oxygen (O2) in exhaust gas based on a signal from the NOx sensor and to calculate a current fuel injection quantity based on the O2 in the exhaust gas and determined fresh air mass flow into the intake, to compare the current fuel injection quantity to a theoretical fuel injection quantity under current operating conditions, and to adjust an amount of fuel injection from the one or more fuel injectors when the current fuel injection quantity differs from the theoretical fuel injection quantity to make the current fuel injection quantity closer to the theoretical fuel injection quantity.

A method for adjusting a fuel mass to be injected into an internal combustion engine. The internal combustion engine including an intake tract, at least one cylinder, and an exhaust tract. In the method, an air mass introduced into the internal combustion engine is ascertained and a fuel mass to be injected into the internal combustion engine is determined. An air-fuel ratio in the exhaust tract of the internal combustion engine is determined which is adjusted in time. Based on the time-adjusted air-fuel ratio and the calculated fuel mass to be injected, a first wall film fuel mass is calculated and the fuel mass to be injected is adjusted based on the first wall film fuel mass.