A method for detecting defective injectors includes operating an internal combustion engine in an idling mode and deactivating mixture control of the internal combustion engine. The method also includes switching off selectively each injector of the respective injection group, detecting the change in the characteristic value when the respective injector is switched off, and checking a fault criterion. The fault criterion is satisfied when the change in the characteristic value for the respective switched-off injector exceeds or undershoots a predetermined amount. The method also includes detecting a defect in the respective injector in response to the fault criterion being satisfied.

Various methods and systems are provided diagnosing a valve. In one example, a system comprises a valve configured to regulate a fuel flow, and a controller configured to determine degradation of the valve based on an initial opening characteristic of the valve.

A method for checking a parameter correlating with a pressure in a pressure-dependent fluid delivery system, the fluid delivery system having: a current-controlled electric motor controlled by a motor controller, and a fluid pump driven by the electric motor, includes: determining a rotational speed of the electric motor; determining a current of the electric motor, by reading out an activation current of the motor controller; calculating a pressure value as a function of the rotational speed and the current of the electric motor; and comparing the calculated pressure value with the parameter.

Methods and apparatuses for connecting multiple loads with a common return pin in engine control module application are disclosed. Only one of the multiple loads can be connected to a power source at a time. At the high side, each load is coupled to the power source through a respective pin at a connector. At the low side, the multiple loads share a common return pin at the connector that connects the loads to the ground. When a first load is connected to the power source at the high side, a first low side driver circuit is used to connect the first load to the ground at the low side. When a second load is connected to the power source at the high side, the second low side driver circuit is used to connect the second load to the ground at the low side.

An internal combustion engine includes an exhaust valve, a plurality of cams Ca, Cb, and Cc used to drive the exhaust valve, a cam-switching variable valve mechanism that selects a use cam used to drive the exhaust valve out of the plurality of cams Ca, Cb, and Cc, and an electronic control unit that determines whether switching abnormality of the use cam in the variable valve mechanism is present on the basis of a locus M in a predetermined period K which is a period in which the exhaust valve is opened. The locus M is a locus of an in-cylinder pressure changing rate dPc/dθ and is specifically a locus indicating a variation of the in-cylinder pressure changing rate dPc/dθ depending on a crank angle θ.

Methods and systems for calculating a plurality of aging factors in a system operating an engine. The calculated aging factors may include one or more of fuel injector drift, exhaust gas recirculation valve obstruction, and mass air flow sensor bias. Mass flow throughout the system, and pressures and temperatures within the system, are observed in an approach that relies on mass preservation concepts to estimate fuel injector drift, exhaust gas recirculation valve obstruction, and mass air flow sensor bias.

A diagnostic system for a vehicle includes a difference module, a Fourier module, and a fault module. The difference module determines pressure differences for a camshaft revolution based on differences between: first pressures within first chambers of a camshaft phaser measured during the camshaft revolution, wherein the first pressures within the first chamber control advancement of the camshaft relative to a crankshaft of an engine; and second pressures within second chambers of the camshaft phaser measured during the camshaft revolution, wherein the second pressures within the second chamber control retardation of the camshaft relative to the crankshaft of the engine. The Fourier module performs a Fourier Transform (FT) based on the pressure differences to produce FT data. The fault module, based on the FT data, selectively indicates that a fault is present in a variable valve lift mechanism that is actuated by the camshaft.

Methods are provided for identifying degradation in components of a compressor recirculation valve (CRV). One method may include inferring degradation of the CRV based on adaptation of a compressor surge line outside an expected range.

An internal combustion engine includes a twin entry type turbocharger with which a first exhaust passage and a second exhaust passage respectively communicate individually, a communication path that causes the first exhaust passage and the second exhaust passage to communicate with each other, a communication valve that opens and closes the communication path, an abnormality diagnosis device that diagnoses presence or absence of abnormality of the communication valve, a variable valve timing mechanism capable of changing a period of valve overlap of the engine, and a control device. When it is determined that abnormality of a valve closure failure of the communication valve is present, the control device operates the mechanism to reduce the valve overlap in an operating state in which the communication valve is closed, more than in a case where it is determined that abnormality of a valve closure failure of the communication valve is absent.

Methods are provided for engine coolant system diagnostics. In one example, engine coolant system malfunction is indicated based on an engine coolant temperature inference model, whereas in another example engine coolant system malfunction is indicated based on a time-based monitor, where the inference model is enabled at ambient temperatures above a predetermined threshold, and where the time-based monitor is enabled at ambient temperatures below the predetermined threshold. In this way, accurate engine coolant system diagnosis may be accomplished under ambient temperature conditions wherein the engine coolant temperature inference model may be compromised.