Methods and systems are provided for restarting an engine following an engine idle-stop. In one example, a method may include, prior to an engine restart following an idle-stop, adjusting a spark ignition timing based on an estimation of a fuel-air equivalence ratio (phi) and an estimation of a cylinder turbulence. Optimal spark ignition timing based on estimated phi and cylinder turbulence during engine restart may result in stabilized combustion and a torque output sufficient to at least partially relieve demand on the starting device.

A control device is configured to perform, when it is estimated that a combustion fluctuation increases, estimation related to an ignition delay for initial flame generated from a discharge spark and an air-fuel mixture containing fuel spray injected by intake stroke injection. When it is estimated that the ignition delay for the initial flame is increased from that before the increase in the combustion fluctuation, an injection amount in expansion stroke injection is reduced in a next time cycle. When it is estimated that the ignition delay for the initial flame is reduced from that before the increase in the combustion fluctuation, the injection amount in expansion stroke injection is increased in a next time cycle.

An exhaust gas analyzer to analyze exhaust gas discharged from an internal combustion engine includes an infrared light source, a photodetector, a CO.sub.2 concentration calculation part and an O.sub.2 concentration calculation part. The infrared light source irradiates infrared light to the exhaust gas. The photodetector detects infrared light after passing through the exhaust gas. The CO.sub.2 concentration calculation part calculates a CO.sub.2 concentration in the exhaust gas on the basis of a detection signal obtained by the photodetector. The O.sub.2 concentration calculation part calculates an O.sub.2 concentration in the exhaust gas from the CO.sub.2 concentration by using a fuel combustion reaction equation and an EGR rate in an exhaust gas recirculation system or a value related to the EGR rate.

A method and system is provided for correcting fueling commands. For example, the method and system may calibrate an engine operating in a steady-state mode by determining a plurality of accuracy errors associated with a fueling rate based on a plurality of sensor measurements. The method and system may determine fueling rate correction data during on-line operation of the engine based on the plurality of accuracy errors. The on-line operation of the engine may comprise operating the engine in a transient mode at a first period of time and a steady-state mode at a second period of time. The method and system may control at least one fueling valve during operation of the engine using a corrected fueling command. The corrected fueling command is based on the fueling rate correction data.

An internal combustion engine includes an engine block including a cylinder a piston positioned within the cylinder and configured to reciprocate in the cylinder, an electronic throttle control system comprising a motor and a throttle plate, a fuel system for supplying a controlled amount of fuel to the cylinder including a fuel injector, and an engine control unit coupled to the fuel system and the electronic throttle control system. The engine control unit is configured to determine engine speed data comprising a current engine speed, a previous engine speed, and a desired engine speed and control a fuel injection duration based on the engine speed data.

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.

In a case where an internal combustion engine is executing an all-cylinder operation to operate all cylinders, an air-fuel ratio estimation part of an ECU 1 estimates an air-fuel ratio of each of the cylinders by using a first observer. On the other hand, in a case where the internal combustion engine is executing a cylinder-cut operation to rest a part of the cylinders and to operate other of the cylinders, the air-fuel ratio estimation part does not estimate the air-fuel ratio of each of the cylinders by using the first observer.

This disclosure provides a system and method for controlling internal combustion engine system to reduce operation variations among plural engines. The system and method utilizes single-input-single-output (SISO) control in which a single operating parameter lever is selected from among exhaust gas recirculation (EGR) fraction and charge air mass flow (MCF), and a stored reference value associated with the selected lever is adjusted for an operating point in accordance with a difference between a measured emissions characteristic and a pre-calibrated reference value of the emissions characteristic for that operating point. Adjusting the selected operating parameter lever towards the theoretical pre-calibrated reference value of the operating parameter lever for each of plural operating points can reduce engine-to-engine variations in engine out emissions.

A fuel injection control unit includes: a first transience determination unit which determines an accelerating state when the first intake pressure differential integration value in a section including a compression stroke, an expansion stroke and an exhaust stroke is greater than a first acceleration determination threshold value; a first transient fuel injection amount calculation unit which calculates an additional fuel injection amount on the basis of the first intake pressure differential integration value; a second transience determination unit which determines an accelerating state when the second intake pressure differential integration value in a section including an intake stroke is greater than a second acceleration determination threshold value which is smaller than the first acceleration determination threshold value; and a second transient fuel injection amount calculation unit which calculates an additional fuel injection amount on the basis of the second intake pressure differential integration value.

A method comprising adjusting a fuel injection amount based on a fractional oxidation state of a catalyst, the fractional oxidation state based on reaction rates of grouped oxidant and reductant exhaust gas species throughout a catalyst and a low-dimensional physics-based model derived from a detailed two-dimensional model to obtain a one-dimensional model averaged over time and space that accounts for diffusion limitations in the washcoat and accurately predicts emissions during cold start.