Systems and methods for operating an engine operated by a controller that has a capacity to determine whether or not misfire occurs in the engine are presented. In one example, an operating region of the engine is broken into a plurality of zones and a misfire threshold level is dynamically provided for each of the plurality of zones based on slowly updated zone-level statistical parameters and quickly updated buffer-level parameters. The real-time dynamic misfire thresholds provide a basis for determining misfire within the engine.

Methods and systems are disclosed for operating an engine that includes a knock control system. The methods and system provide for repurposing the engine knock control system to detect and mitigate piston slap. The methods and systems also seek to increase the signal to noise ratio for detecting piston slap.

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 the basis for establishing the presence or absence of knock in one or more engine cylinders.

A method for detecting a damaged-bearing in an engine using a vibration signal may include: separating, by a controller, a vibration signal of the engine detected by a vibration detecting device installed on one side of the engine of a vehicle into a vibration signal caused by combustion knocking and a vibration signal generated in a bearing, extracting a signal in a predetermined natural frequency band from the vibration signal generated in the bearing using a band-pass filter, and processing the extracted signal to a quantified bearing signal using the controller, and comparing the quantified bearing signal with a preset damaged-bearing criterion using the controller to determine whether the quantified bearing signal is equal to or higher than the preset damaged-bearing criterion to determine a damage to the bearing.

A method of operating an internal combustion engine with at least one piston-cylinder unit, and preferably a plurality of the piston-cylinder units, whereby, in a detection mode of the internal combustion engine one or more knock-promoting measures are taken until knocking has occurred in at least one piston-cylinder unit, and the measure(s) is/are intensified until a termination criterion is reached, whereby it is detected in which of the piston-cylinder units knocking has occurred, and whereby, in piston-cylinder units detected as knocking, the ignition time for a normal operating mode of the internal combustion engine is retarded.

A method for detecting a damaged-bearing in an engine using a vibration signal may include: separating, by a controller, a vibration signal of the engine detected by a vibration detecting device installed on one side of the engine of a vehicle into a vibration signal caused by combustion knocking and a vibration signal generated in a bearing, extracting a signal in a predetermined natural frequency band from the vibration signal generated in the bearing using a band-pass filter, and processing the extracted signal to a quantified bearing signal using the controller, and comparing the quantified bearing signal with a preset damaged-bearing criterion using the controller to determine whether the quantified bearing signal is equal to or higher than the preset damaged-bearing criterion to determine a damage to the bearing.

In one embodiment, a method is provided. The method includes receiving a signal representative of an engine vibration transmitted via a knock sensor, wherein the knock sensor is disposed in an engine. The method additionally includes deriving a valve wear measurement during operation of the engine based on the signal. The method further includes communicating the valve wear measure.

A method and a device are provided for controlling an internal combustion engine, a knock sensor being provided for acquiring combustion signals of the internal combustion engine. Devices are also provided that, during running operation of the internal combustion engine, select operating ranges of the internal combustion engine that are suitable for a determination of fuel quality, and carry out a determination of the fuel quality in these ranges on the basis of signals of the knock sensor.

A method is provided for detecting autoignition in a spark-ignited internal combustion engine, wherein values for the combustion chamber pressure are measured during a compression stroke of the internal combustion engine at defined crankshaft angles within an evaluation window, a filtered pressure value is determined from the measured values for the combustion chamber pressure, and theoretical pressure values in the combustion chamber that would arise if no combustion took place in the combustion chamber are determined for the defined crankshaft angles. The value of the slope between two defined crankshaft angles for filtered pressure values is determined, the value of the slope between two defined crankshaft angles for theoretical pressure values is determined, and a difference of the slope values is calculated therefrom. This difference is compared with a specified threshold value, and, if the threshold value is exceeded, an autoignition in the combustion chamber is inferred.

A computer-implemented platform may comprise hardware and software configured to estimate knock intensity and/or manage an engine using knock intensity data. A plurality of knock indicators may be used to model a knock response, providing an improved estimate of knock intensity. Knock intensities from a plurality of combustion cycles may be used to estimate a statistical distribution of knock intensities. The statistical distribution may be used to determine an engine tune state. An engine tune state may be modified via the incorporation of prior knock intensity statistics.