Some examples described herein may involve determining an advance timing window between the valve opening or closing and a designated time that the valve is scheduled to open or close; determining a closing velocity of the valve; monitoring an engine speed of the engine; determining valve lash information based on the advance timing window, the closing velocity, and the engine speed, wherein the valve lash information identifies a magnitude of the valve lash or whether the magnitude of the valve lash associated with the valve satisfies a threshold; and performing an action based on the valve lash information.

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.

Various embodiments include a method for identifying an inlet and an outlet valve stroke phase difference comprising: measuring pressure oscillations during operation; generating a corresponding signal; determining a corresponding crankshaft phase angle; applying a discrete Fourier transformation to the pressure signal to determine amplitudes of selected frequencies in relation to the crankshaft phase angle; determining lines of equal amplitudes of the frequencies based on the amplitudes depending on the phase differences using reference lines; determining an intersection of the lines by projection into a common plane; and determining the inlet valve stroke phase difference and the outlet valve stroke phase difference from the determined common intersection point of the lines of equal amplitudes of the selected signal frequencies.

An internal combustion engine includes a cam-actuated rocker arm assembly with a solenoid-actuated latch that provides for cylinder deactivation or variable valve actuation. The solenoid is in a position where its inductance varies significantly in relation to the position of a latch pin as it translates between latching and non-latching configurations. A sensor is positioned to monitor a current or a voltage in a circuit that includes the solenoid. The sensor data is analyzed to provide diagnostic information relating to the operation of the rocker arm assembly.

A control device is configured, if, although the control device has caused a cam switching device to perform a first cam switching operation for switching the profiles of all the valve-driving cams of a plurality of cylinders from a first profile to a second profile, the profiles of all the valve-driving cams of the plurality of cylinders do not coincide with the second profile, to cause the cam switching device to perform a second cam switching operation for switching the profile of the valve-driving cam for at least one or more normal cylinders that are one or more cylinders at which the switching of profiles to the second profile has succeeded.

An electronic control unit of a control device for an internal combustion engine executes, for a first cycle, first drive processing for controlling an actuator such that a pin drive operation is executed for switching from a first cam to a second cam, executes second drive processing for controlling the actuator such that the pin drive operation is executed again for a second cycle, and executes abnormality determination processing for determining that a cam switching mechanism has an abnormality in a case where a pin returns to a reference position by using a pin return section following a cam switching section of the first cycle after the execution of the first drive processing and the pin returns to the reference position by using the pin return section following the cam switching section of the second cycle after the execution of the second drive processing.

Methods and systems are provided for estimating engine oil temperature during conditions when sensors used for engine oil temperature measurement are not functional or not reliable. A null duty cycle of a solenoid spool valve of a variable cam timing mechanism is estimated. Then, a calibrated relationship between the duty cycle, an angular velocity of the associated cam, and the engine oil temperature is used to estimate an engine oil temperature when existing sensors used in the calculation of engine oil temperature calculation become unreliable.

A method for diagnosing the valve timing of an internal combustion engine, a characteristic curve of an actual intake manifold pressure signal being ascertained as a function of a crankshaft signal, the characteristic curve of the actual intake manifold pressure signal being compared to a characteristic curve of a setpoint intake manifold pressure signal and a shift of the valve timing being diagnosed in the event of a specifiable deviation of the actual intake manifold pressure signal from the setpoint intake manifold pressure signal.

In a control device and a control method for a variable valve timing mechanism according to the present invention, the rotational phase of a camshaft is measured based on the cam angle signal and crank angle signal upon receiving each pulse of the cam angle signal, and the rotational phase change over time within a period of the cam angle signal is measured based on the motor angle signal. It is decided whether the cam angle signal and/or crank angle signal has a prescribed pulse pattern at a diagnostic timing that comes after the last pulse of the cam angle signal. When this decision result is positive, it is then decided whether the motor angle sensor operates normally or abnormally based on the rotational phase and the amount of rotational phase change that are measured when the last pulse of the cam angle signal is received before the diagnostic timing.

An internal combustion engine includes a cylinder head and a valvetrain including a poppet valve, a cam shaft on which is mounted a cam, and a rocker arm assembly. The rocker arm assembly includes a rocker arm and a cam follower configured to engage the cam as the cam shaft rotates. The rocker arm assembly is operative to transmit force from the cam to actuate the valve and includes an electrical device mounted to the rocker arm. A first electrical circuit includes the electrical device and a first conductor mounted to the rocker arm and a second electrical circuit includes a second conductor mounted off the rocker arm. The first and second conductors are inductively coupled to an extent that enables effective power transfer or communication between them. Inductive power transfer avoids the use of wires that could become caught, clipped, or fatigued and consequently short out.