A system for detecting and controlling air-fuel ratio imbalance conditions between cylinders of an internal combustion engine having a plurality of cylinders is disclosed.

A system and method monitor operation of a compressor, determine whether the operation of the compressor is outside of a designated range of values, and, responsive to determining that the operation of the compressor is outside of the designated range of values, one or more of (a) prevent communication of a signal to a system controller that controls operation of the compressor, (b) direct a gas from a reservoir to a pressure sensor used by the system controller to determine a gas pressure generated by the compressor, and/or (c) communicate the signal to the system controller that controls operation of the compressor.

Systems and methods are provided for diagnosing cylinders. In one example, a system includes an engine having a plurality of cylinders coupled to a crankshaft, a crankshaft speed sensor, and a controller. The controller is configured to receive a first output from the crankshaft speed sensor during nominal engine operation, receive a second output from the crankshaft speed sensor during engine operation where a fueling disturbance is introduced to a cylinder of the plurality of cylinders, indicate that the cylinder is unhealthy responsive to a difference between the first output and the second output being less than a threshold difference, and adjust one or more operating parameters of the engine in response to the indication.

Methods and systems are provided for a diagnostic routine of a variable displacement engine (VDE) of a vehicle to detect non-deactivated valves of deactivated cylinders due to a degraded valve deactivation mechanism. In one example, a method comprises, during operation of the VDE with one or more cylinders of the VDE deactivated, calculating a variation in a fast-sampled signal outputted by one or more exhaust gas oxygen (EGO) sensors of the VDE over a plurality of engine cycles; determining that the variation is greater than the threshold variation; and in response, indicating that valves of the one or more cylinders are not deactivated. A second method comprises estimating a throttle air flow rate and an engine air flow rate of the VDE; and indicating non-deactivated valves of one or more deactivated cylinders if the throttle air flow rate exceeds the engine air flow rate by a threshold.

A system and method for dynamically deactivating engine cylinders of an engine equipped with a cylinder deactivation system, where the system and method control torsional vibration in the engine while deactivating cylinders using a computer programed with a desired firing density and a controlled range of engine vibration frequencies. The computer dynamically determines a cylinder firing pattern that provides the desired firing density while optimizing a cost function norm in the controlled range of engine vibration frequencies. The cylinder deactivation system in the engine is then controlled using the determined cylinder firing pattern.

A knocking determination device detects a vibration generated in an internal combustion engine during a predetermined period in each combustion cycle of the internal combustion engine. The knocking determination device performs a knocking determination of a presence or absence of a knock based on a vibration waveform in a predetermined frequency band component of the vibration detected.

A system for detecting and controlling misfire and/or AFR imbalance conditions in cylinders of an internal combustion engine having a plurality of cylinders is disclosed.

A method for diagnosing the dynamics of a sensor in the fresh air or exhaust gas tract of internal combustion engines, as well as a computer program, a computer program product and a corresponding vehicle. It is provided that a corresponding sensor for measuring a pressure signal in the fresh air or exhaust gas tract of an internal combustion engine of a vehicle, which is coupled with a control and computing unit, is checked with respect to its dynamic characteristics. Measured values of differing frequency ranges are measured, these being used as the basis for a calculation of a characteristic. After the calculation, the characteristic is compared with a threshold value stored in a user-defined manner in the control and computing unit. If the calculated characteristic deviates from the threshold value, at least one triggering signal is triggered, so that an impaired sensor dynamic of the sensor is displayed.

A data processing method of variable measurement data in an electronic control unit (ECU) is provided. The ECU that processes the data processing method calculates a filtering frequency based on a delay time frequency based on a transmission timing cycle of the measurement data and a processing timing cycle of the measurement data in the ECU, and also based on a pulsation frequency of the measurement data, and removes, from the measurement data, a component of the filtering frequency calculated in the calculation of the filtering frequency.

A method for determining a combination of an actual intake camshaft phase position of an intake camshaft and an actual exhaust camshaft phase position of an exhaust camshaft of a production internal combustion engine having at least one cylinder, wherein the method is performed in operation of the production internal combustion engine and the relevant actual phase position of the camshafts is determined in relation to an operating point of the production internal combustion engine.