Various methods and systems are provided for diagnosing a condition of a fuel injector of an engine. In one example, a method for an engine includes injecting a first pulse of fuel as a first pilot injection into a first subset of cylinders of a plurality of engine cylinders, where the first pilot injection precedes a primary injection of fuel into the first subset of cylinders by a duration; correlating a first response in an engine operating parameter to the first pilot injection; and adjusting the primary injection of fuel into the first subset of cylinders based on the first response. In one example, the first pilot injection precedes the primary injection by a predefined short duration and the primary injection of fuel is adjusted within a predefined or preset upper limit and lower limit.

A method and diagnostic tool diagnoses a charge cycle behavior of an internal combustion engine with a plurality of cylinders. The method determines a diagnosis time window within a torque dropout of one of the cycles of the internal combustion engine, and associates a deviation type with the diagnosis time window determined.

To provide a controller and a control method for an internal combustion engine capable of performing automatic adaptation of the optimal ignition timing or the optimal control value of the combustion operation mechanism during operating. A controller and a control method for an internal combustion engine changes setting values of a torque characteristics function so that an output torque calculated using the torque characteristics function approaches an output torque calculated based on an actual value of internal cylinder pressure; calculates a plurality of output torques corresponding to respective plurality of combustion control states using the torque characteristics function; and changes setting values of a combustion control target setting function so that a target value of combustion control state calculated using the combustion control target setting function approaches a maximum torque combustion control state where the output torque becomes the maximum.

A method for controlling engine combustion may include receiving a signal of a crank position sensor, determining an angular velocity and an angular acceleration of a crank on the basis of the signal of the crank position sensor, determining a combustion characteristic index for each cylinder using the angular velocity and the angular acceleration of the crank, judging an unstable combustion cylinder using the combustion characteristic index for each cylinder, and changing a combustion factor for controlling the unstable combustion cylinder.

A method for controlling an internal combustion engine is provided, which includes defining a first area in which the engine operates in a stoichiometric combustion mode and a second area in which the engine operates in a lean combustion mode, on an operation map defined by the engine load and speed, and causing a controller to determine that an operation point on the operation map shifts from the first area to the second area based on signals from an accelerator opening sensor and a crank angle sensor, predict a length of time that the operation point stays in the second area, switch a combustion mode to the lean combustion mode when the predicted time is longer than a given period of time, and maintain the stoichiometric combustion mode when the predicted time is shorter than the given period of time.

To provide a controller and a control method for an internal combustion engine capable of performing automatic adaptation of the optimal ignition timing or the optimal control value of the combustion operation mechanism during operating. A controller and a control method for an internal combustion engine changes setting values of a torque characteristics function so that an output torque calculated using the torque characteristics function approaches an output torque calculated based on an actual value of internal cylinder pressure; calculates a plurality of output torques corresponding to respective plurality of combustion control states using the torque characteristics function; and changes setting values of a combustion control target setting function so that a target value of combustion control state calculated using the combustion control target setting function approaches a maximum torque combustion control state where the output torque becomes the maximum.

In accordance with an exemplary embodiment, a method is provided for controlling operation of an engine of a vehicle during an idle mode of operation for the engine, the engine having a plurality of different types of fuel injectors and a combustion chamber, including: obtaining, via one or more first sensors of the vehicle, first sensor data as to a speed of the vehicle; obtaining, via one or more second sensors of the vehicle, second sensor data as to a measure of roughness of the engine; and adjusting, via instructions provided by a processor of the vehicle, a fuel injection ratio of respective amounts of fuel provided by the plurality of different types of fuel injectors to the combustion chamber, based on both the speed of the vehicle and the measure of roughness of the engine.

An air-fuel ratio control device sets a target air-fuel ratio and performs an air-fuel ratio control based on the target air-fuel ratio for an engine of a spark ignition type. The air-fuel ratio control device includes a lean combustion determination unit that determines whether a lean combustion is performed in the engine at the target air-fuel ratio, the target air-fuel ratio being set leaner than the theoretical air-fuel ratio; a target NOx setting unit that sets a target NOx concentration according to an operation state of the engine; an acquisition unit that acquires an actual NOx concentration detected by using a NOx concentration detection unit in an exhaust passage of the engine; and a correction unit that corrects the target air-fuel ratio based on the target NOx concentration and the actual NOx concentration when determination is made that lean combustion is performed.

A rotation adjusting device is controlled such that an engine speed rising rate at the time of acceleration request is made smaller when a turbocharging pressure is lower than the turbocharging pressure is higher. Therefore, an engine speed can be increased at such a low speed that a rising delay in the turbocharging pressure hardly occurs, in a low turbocharging pressure region. Further, when the rotation adjusting device is controlled such that the engine speed rising rate at the time of the acceleration request is set to a value corresponding to the turbocharging pressure, an MG2 torque is controlled to compensate for an insufficient drive torque of an actual engine torque for a request engine torque. Therefore, even when the engine torque is increased slowly by increasing the engine speed at a slow speed, the insufficient drive torque is compensated for by the MG2 torque.

Using machine learning for cylinder misfire detection in a dynamic firing level modulation controlled internal combustion engine is described. In a classification embodiment, cylinder misfires are differentiated from intentional skips based on a measured exhaust manifold pressure. In a regressive model embodiment, the measured exhaust manifold pressure is compared to a predicted exhaust manifold pressure generated by neural network in response to one or more inputs indicative of the operation of the vehicle. Based on the comparison, a prediction is made if a misfire has occurred or not. In yet other alternative embodiment, angular crank acceleration is used as well for misfire detection.