The invention relates to a method for adapting the composition of a mixture of fuel and combustion air. The mixture is supplied to a combustion chamber of a mixture-lubricated combustion engine in a work apparatus. The fuel is supplied to the combustion engine via a controlled fuel valve. In an operating state (I) of the combustion engine, the quantity of fuel is metered by the fuel valve. For the purpose of adapting the composition of the mixture, the combustion engine is shifted into a special operating state (II) which differs from the normal operating state (I). After starting, the combustion engine is operated in a first rotational speed range (B) for a prespecified operating time (T.sub.min), wherein, after the prespecified operating time (T.sub.min) has elapsed, the operating state (II) for adapting the composition of the mixture is initiated by a prespecified user action.

Since a factor affecting an individual difference learning result is reduced or eliminated regardless of a valve body behavior, it is possible to highly accurately detect an individual difference of a fuel injector caused by the valve body behavior and to reliably detect the individual difference even when the fuel injector is replaced. When a valve opening/closing timing of the fuel injector is learned by a learning unit, a unit of interrupting the learning if a predetermined condition is established, a unit of prohibiting the learning of the valve closing timing using the learning unit if a predetermined condition is established, or a unit of prohibiting the learning of the valve opening/closing timing of the fuel injector using the learning unit if a fuel pressure of a common rail supplying a fuel to the plurality of fuel injectors changes by a predetermined value or more within a predetermined time is provided.

A method for engine drivability robustness includes: dividing, by an engine controller, an engine state into a starting condition, a stop condition, and a deceleration condition; dividing an injection mode index of a fuel injection into a suction compression injection of the starting condition, a suction split injection of the stop condition, and a suction compression split injection of the deceleration condition, respectively, depending on a low volatile fuel condition; and performing a variable indexing mode to prevent an engine off by applying a lambda control factor for a rich lambda control by an increase in fuel amount to the deceleration condition.

An engine includes a low-pressure delivery pipe that stores fuel to be injected from port injection valves, a feed pump that supplies the fuel to the low-pressure delivery pipe, a high-pressure delivery pipe that stores the fuel to be injected from in-cylinder injection valves, a high-pressure pump driven in response to rotation of the engine, and a fuel pressure sensor that detects a pressure of the fuel stored in the low-pressure delivery pipe. An engine ECU controls the feed pump based on a detection value from a fuel pressure sensor, and when the engine ECU executes an abnormality diagnosis of the fuel pressure sensor, the engine ECU increases a rotational speed of the engine to be higher than a rotational speed when the engine ECU does not execute an abnormality diagnosis of the fuel pressure sensor. This improves the accuracy of an abnormality determination of the fuel pressure sensor.

In an engine having an electronically controlled hydraulic system for variable actuation of intake valves, an operating step of refilling, prior to ignition of the engine, is activated to refill a pressure chamber of the system with fluid when, after prolonged engine inactivity, the chamber has been emptied. In this refilling step, fuel supply to the engine is inhibited, and a camshaft is rotationally driven following upon activation of an engine-starting electrical machine. In this way, a pumping member associated to a tappet for actuating an intake valve is used as a pump for drawing fluid into the pressure chamber from an auxiliary fluid tank. During this step, a control valve is opened and closed in synchronism with movement of the pumping member so as to be open when the pumping member advances towards the pressure chamber and closed when the pumping member moves away from the pressure chamber.

A method of operating a forced induction gaseous-fueled engine includes mixing gaseous-fuel and engine intake air to form a mixture at a fuel mixer. The method includes delivering the mixture to an intake manifold by at least partially bypassing a charge air cooler.

Methods and a system are provided for controlling fuel injection in a vehicle engine. The system specifically relates to an engine fueled with both port and direct fuel injectors. In one example, a method may include delivering a first portion of fuel via port injection during a first injection window, and subsequently delivering a second portion of fuel directly during a second injection window before the engine exits cranking speeds.

Methods and a system are provided for controlling fuel injection in a vehicle engine. The system specifically relates to an engine fueled with both port and direct fuel injectors. In one example, a method may include delivering a first portion of fuel via port injection during a first injection window, and subsequently delivering a second portion of fuel directly during a second injection window before the engine exits cranking speeds.

A method is provided for controlling the torque of an engine when a DPF is regenerated and includes detecting outputs of a gear pump and a main hydraulic pump as parameters for correcting a DPF regeneration condition, increasing the flow rate of the gear pump or main hydraulic pump, controlling the torque of an engine so as to reach a predetermined target engine torque value as the flow rate of the gear pump or main hydraulic pump is increased, starting DPF regeneration when the torque of the engine reaches the predetermined target engine torque value, allowing the number of revolutions of the engine to be increased on the basis of the target engine torque value during the DPF regeneration, and performing the DPF regeneration until the temperature of exhaust gas reaches a predetermined target DPF regeneration temperature.

Methods and systems are provided for controlling exhaust emissions by adjusting an injection profile for different fuels injected into an engine cylinder from different fuel injectors during engine start and crank. By splitting fuel injection during start and cranking so that fuel of lower alcohol content is port injected and fuel of higher alcohol content is direct injected as one or multiple injections, the soot load of the engine can be reduced and fuel economy can be improved.