A control device for an internal combustion engine is provided that can detect the adherence of deposits to a cylinder pressure sensor without subjecting the internal combustion engine to an impact or the like. A control device for an internal combustion engine equipped with a cylinder pressure sensor detects changes in the sensitivity of the cylinder pressure sensor. If the control device detects a decrease in the sensitivity of the cylinder pressure sensor after detecting an increase in the sensitivity of the cylinder pressure sensor, the control device determines that deposits are adhered to the cylinder pressure sensor.

Methods and systems are provided for adjusting spark and/or fuel injection to a cylinder based on late combustion, partial burn, or misfire in a neighboring cylinder. In one example, a method may include deactivating spark and fuel injection to a second cylinder receiving exhaust residuals from combustion in a first cylinder, the first cylinder experiencing a misfire or late combustion event. Mitigating actions are performed in the second cylinder before the occurrence of a pre-ignition event.

A method of deriving reciprocating device component health includes receiving a signal from a knock sensor coupled to a reciprocating device, deriving total harmonic distortion (THD) at one or more frequencies, and determining whether the derived THD exceeds a threshold value.

In a spark-ignition internal combustion engine having multiple cylinders, successive segment time periods assigned to the individual cylinders during working strokes thereof, and subsequently irregular running values are determined from the segment time periods. In a predefined speed range of the engine, the irregular running values of the cylinders are compared with a predefined threshold, and suspected auto-ignition for a first cylinder is detected if the irregular running value of a second cylinder located before the first cylinder in terms of timing of the ignition sequence undershoots the threshold. Fuel to the first cylinder suspected of auto-ignition is interrupted for a predefined number of cycles, and the fuel interruption influence on the irregular running values of the second cylinder during the cycles is detected. The suspected auto-ignition of the first cylinder is either confirmed or rejected based on the irregular running values occurring at the second cylinder.

A knock determination apparatus for an internal combustion engine calculates a knock intensity based on an output signal of an in-cylinder pressure sensor in a gate range for knock determination. When the calculated knock intensity is larger than a knock determination threshold value, the knock determination apparatus determines that knock has occurred. Further, the knock determination apparatus calculates an integrated intensity which is an integrated value of knock intensities that are equal to or larger than a knock intensity at a point of 97% or more in a target knock level among knock intensities that are calculated at the respective cycles during continuous N cycles in the same cylinder. Furthermore, the knock determination apparatus corrects a knock determination threshold value so that the difference between the calculated integrated intensity and a target integrated intensity becomes small.

A method for detecting glow ignition of a fuel-air mixture in a combustion chamber of an internal combustion engine having at least one first cylinder and at least one second cylinder, the at least one first and second cylinders being connected by a crankshaft, according to which method partial segment times of the at least one first cylinder are measured. The method is characterized in that partial segment times of the at least one second cylinder are measured and a reference characteristic for the glow ignition is formed by a comparison of partial segment times of the at least one first cylinder with partial segment times of the at least one second cylinder and subsequently a signal is generated for the detection of the glow ignition on the basis of the comparison.

An ion current detection circuit is for detecting an ion current flowing through a spark plug for an internal combustion engine. A detection terminal is to be electrically connected to the spark plug. A reference potential is to be supplied to a reference terminal. At least one protection diode is provided between the detection terminal and the reference terminal. A current detection unit causes a detection current to flow between the detection terminal and the at least one protection diode. A current compensation unit causes a compensation current to flow between the detection terminal and the at least one protection diode.

A method of monitoring an operating event of a combustion engine includes receiving a noise signal sensed by a knock sensor disposed in or proximate to the combustion engine, correlating the noise signal with a musical instrument digital interface (MIDI) fingerprint having at least an ADSR envelope indicative of the operating event, and detecting if the operating event has occurred based on the correlating of the noise signal with the fingerprint.

A specific sound having a higher frequency than an operation sound of an engine is generated in synchronization with timing of a top dead center of a specific cylinder of the engine. Thus, timing of a noise of the engine is estimated by using, for example, a deviation in time between timing of generation of a specific sound and timing at which a noise occurs in the engine, based on a sound collected from around the engine without directly using a signal of a crank angle of the engine.

An ion current detection circuit is for detecting an ion current flowing through a spark plug for an internal combustion engine. A detection terminal is to be electrically connected to the spark plug. A reference potential is to be supplied to a reference terminal. At least one protection diode is provided between the detection terminal and the reference terminal. A current detection unit causes a detection current to flow between the detection terminal and the at least one protection diode. A current compensation unit causes a compensation current to flow between the detection terminal and the at least one protection diode.