A CPU performs a regeneration process for a GPF by stopping combustion control of cylinder #1 and causing an air-fuel ratio of an air-fuel mixture in the other cylinders to be richer. The CPU calculates a rotational fluctuation amount which is used to detect random misfires in which a misfire rate in a predetermined period is equal to or greater than a predetermined proportion by calculating a difference in time et3txdh in which a crank shaft rotates by 30°CA. At the time of performing the regeneration process, the CPU calculates the rotational fluctuation amount based on a value obtained by removing an influence of torsion of a damper from the time et3txdh. When the influence of torsion is removed, 0.5th-order rotation and harmonics thereof are selectively used using a filter process.

A CPU stops combustion control of Cylinder #1 in order to perform a regeneration process of a GPF and performs a regeneration process of causing an air-fuel ratio of an air-fuel mixture in Cylinders #2 to #4 to be richer. When it is determined that a misfire has occurred because a misfire rate when the regeneration process is not being performed is equal to or greater than a predetermined value, the CPU determines that an internal combustion engine has returned to a normal state based on the premise that the misfire rate when the regeneration process is not being performed decreases.

Methods and systems are provided for controlling fuel injectors of an engine. In one example, a system for an engine includes a fuel injector couplable to at least one engine cylinder; and a controller operatively couplable to the fuel injector. The controller is configured to during a first engine cycle, control injection of both a primary pulse of fuel and a pilot pulse of fuel into the at least one engine cylinder via the fuel injector, determining, for the at least one engine cylinder, an amount of adjustment to the primary pulse of fuel, the pilot pulse of fuel, or both the primary and the pilot pulse, and during a second engine cycle, following the first engine cycle, adjusting an amount of the primary pulse of fuel, the pilot pulse of fuel, or both based at least in part on the first response to the pilot pulse of fuel.

A vehicle includes an exhaust passage including an exhaust cleaner, an engine coupled to the exhaust passage, fuel injection valves, and a control device. The fuel injection valves are respectively provided in cylinders of the engine and inject fuel into the cylinders. The control device performs, after main-injection, post-injection control that causes the fuel injection valves to perform post-injection. The control device determines a fuel injection amount for single-time post-injection performed by each fuel injection valve such that the fuel injection amount for the single-time post-injection is greater than a fuel injection amount when the post-injection is performed in every combustion cycle in all the cylinders. The control device performs the post-injection control such that how many times the post-injection is performed is less than how many times the post-injection is performed in a case in which the post-injection is performed in every combustion cycle in all the cylinders.

A CPU determines that there is a misfire when a relative magnitude of a rotation fluctuation amount ΔT30[0] related to a cylinder subject to the determination in relation to a rotation fluctuation amounts ΔT30[4] of the previous combustion cycle is greater than or equal to the determination value Δth. However, during the execution of a catalyst warm-up process, the CPU uses, in the comparison, the relative magnitude of the rotation fluctuation amount ΔT30[0] in relation to the average ΔT30ave[0] of the smallest five of the rotation fluctuation amounts ΔT30[4] to ΔT30[40] from the past ten combustion cycles.

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.

The disclosure relates to a method for identifying a change in the operating behavior of a crankshaft drive of a motor vehicle. In particular, the disclosure relates to a method for identifying error states of a torsional-vibration damper in the crankshaft drive, such as a jamming or slipping of a secondary mass of the torsional-vibration damper. The crankshaft drive comprises a crankshaft, a pulse generator that rotates when the crankshaft is in operation and a fixed sensor device, which generates a rotational speed signal N as a function of the rotational speed of the pulse generator. The method comprises the following steps: detecting a current rotational speed signal N.sub.akt of the sensor device during operation of the crankshaft drive; filtering the current rotational speed signal N.sub.akt using a bandpass filter that has at least one first passband range D1 comprising a first center frequency f1; comparing the filtered current rotational speed signal N.sub.akt with a reference signal N.sub.ref stored in a memory; and identifying a change in the operating behavior of the crankshaft drive on the basis of the comparison of the filtered current rotational speed signal N.sub.akt with the reference signal N.sub.ref. The disclosure further relates to a vehicle, such as a commercial vehicle, having a control device which is configured to perform a method of this kind.

A control device and a control method for variable valve timing mechanism according to the present invention obtains a first measurement of a rotational phase based on a rotational angle of the motor, obtains a second measurement of the rotational phase based on a relative relationship between a rotational angle of the crankshaft and a rotational angle of the camshaft, calibrates the first measurement based on the second measurement, obtains a derivative term proportional to a rate of change in a deviation between the first measurement and a target value, reduces change in derivative term when calibrating the first measurement based on the second measurement, and controls the motor based on a manipulated variable including the derivative term.

A control method for internal combustion engine with a fuel injection valve configured to directly inject fuel into a cylinder and an ignition plug configured to directly spark-ignite the fuel injected from the fuel injection valve includes comparing an actual behavior, which is an actual changing behavior of an engine revolution speed at an engine start, to a reference behavior set in advance, and switching from stratified combustion in which a fuel spray injected from the fuel injection valve and staying around the ignition plug is directly spark-ignited to homogeneous combustion in which a homogeneous air-fuel mixture is formed in a combustion chamber and the fuel is burned and increasing a mechanical compression ratio of the internal combustion engine as compared to the case where the actual behavior and the reference behavior match if the actual behavior is different from the reference behavior.

Methods and systems are provided for operating a variable displacement engine that includes a misfire detection system. The misfire detection system corrects engine crankshaft acceleration according to cylinder firing patterns so that misfire detection may be improved. The corrected engine crankshaft accelerations may be compared to threshold crankshaft levels to determine the presence or absence of cylinder misfire.