A method for monitoring a cylinder pressure sensor, in which method the sensor value is checked for admissibility and inadmissibility in a predefinable crankshaft angle range, when admissibility is detected the cylinder pressure sensor is used further and when inadmissibility is detected the cylinder pressure sensor is deactivated. A first sensor value of the cylinder pressure sensor is set as a start value, and a second sensor value is set as a stop value, a plateau range is determined from the number of sampling steps between the start value and the stop value, and the plateau range is set as decisive for the admissibility or inadmissibility of the sensor values.

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.

Disclosed is a method for determining reliability regarding misfire determination of cylinders of an engine, comprising detecting a pressure in an exhaust manifold for a set of operation parameters comprising a certain range of crank angles for a certain engine load and certain engine speed so as to, for an actual cylinder setup of the engine, create pressure sample value patterns for combustion and misfire conditions. A template course is created for the thus created pressure sample value patterns comprising a set of sample points. The pressure for the created template courses is normalized at a desired crank angle. Difference values are determined based upon differences between sample points and corresponding detected and the normalized pressure values. The determined difference values are summarized so as to determine whether a predetermined share of the summarized difference values lies above or below a predetermined threshold value indicating reliability regarding misfire determination.

A Wiebe function parameter identification method, the method includes: acquiring, by a computer, operation data when an internal-combustion engine is in operation; and identifying values of a plurality of parameters included in a combination of at least two Wiebe functions including a first Wiebe function and a second Wiebe function based on the operation data and a first difference between values of a same parameter of the first Wiebe function and the second Wiebe function.

Methods and systems are disclosed for operating an engine that includes a knock control system that may determine contributions of individual noise sources to an engine background noise level. The contributions of the individual noise sources may be determined via adjusting timing of a knock window or timing of the individual noise sources.

A method and a device for determining combustion noise parameters, comprising acquiring a cylinder pressure sequence which comprises cylinder pressures corresponding to different crank angles φ and corresponding moments t.sub.φ; calculating a first parameter sequence according to the cylinder pressure sequence, wherein the first parameter sequence is a parameter sequence in a time domain, and the first parameter sequence comprises one or more of a top surface cylinder force sequence, a top surface cylinder force rise rate sequence, a side surface cylinder force sequence and a side surface cylinder force rise rate sequence; and determining a target parameter for representing combustion noise in the cylinder according to the first parameter sequence.

A method for detecting knocking of an engine includes receiving a knock signal indicating a vibration level in a cylinder of the engine and a crank angle signal indicating a crank angle by which a knocking window and an end of injection (EOI) of an injector of the engine are expressed, determining whether the knocking window and the EOI overlap, based on the crank angle signal, setting a second reference value for an overlapping range within the knocking window overlapping the EOI by reflecting a predetermined level on a first reference value for a non-overlapping range within the knocking window non-overlapping the EOI depending on the determination, integrating the knock signal in the knocking window, determining whether an integrated value of the knock signal exceeds the first reference value in the non-overlapping range or the second reference value in the overlapping range, and retarding an ignition timing of the engine as a knocking avoidance logic depending on the determination.

A method for detecting valve leakage of a least one valve at a cylinder intake manifold or exhaust manifold of a vehicle engine, the method comprising: acquiring a set of pressure data points indicative of the pressure in the cylinder intake manifold or exhaust manifold for crankshaft angular positions covering crankshaft angular rotation degrees such that each of the at least one valve has opened at least one time; and determining at least one test value based on the set of pressure data points, wherein a valve leakage is detected based on a comparison of the at least one test value to a threshold value.

A method for analyzing a fluid that flows from a chamber, in particular a combustion chamber, of an internal combustion engine into a fluid guide. The internal combustion engine includes at least one element, in particular an injector, for the supply of fuel. The analysis takes place with the aid of a sensor, in particular a lambda sensor, on which the fluid in the fluid guide acts. The analysis takes place during cranking of the internal combustion engine, and the fluid acting on the sensor is not influenced by fuel that is supplied in a controlled manner.

A control system includes a controller. The controller estimates the swing-back amount indicating the turning amount of the crankshaft in the reverse rotation direction until the crankshaft stops. The controller calculates a stop-time counter value which is a value of a crank counter at the time when the engine is stopped based on a final counter value which is the value of the crank counter calculated last before the crankshaft stops and the estimated swing-back amount. The controller corrects the swing-back amount used for calculating the stop-time counter value based on a difference between the number of driving times calculated with reference to the map based on the calculated stop-time counter value and the value of the crank counter and the number of driving times calculated by increasing the number of driving times by one each time the high pressure system fuel pressure increases by the threshold or more.