An exhaust valve system for a two-stroke internal combustion engine having: at least one exhaust valve movable between open and closed positions; an actuator for moving the at least one exhaust valve; a valve position sensor; a controller communicating with the actuator and the valve position sensor. The controller being programmed for: controlling the actuator to attempt to move the at least one exhaust valve to a desired one of the open and closed positions; determining if the at least one exhaust valve has failed to reach the desired position based on the position of the at least one exhaust valve sensed by the valve position sensor; and controlling the actuator to move the at least one exhaust valve to an intermediate position when the at least one exhaust valve has failed to reach the desired position.

An exhaust valve assembly for a two-stroke internal combustion engine has a housing adapted for connection to an engine block of the two-stroke internal combustion engine; an electric actuator having an electric motor, the electric motor being disposed in the housing; and at least one reciprocating exhaust valve operatively connected to the electric actuator. The at least one exhaust valve is linearly movable by the electric motor. A portion of the at least one exhaust valve is disposed in the housing.

A method for detecting valve leakage of a least one valve at a cylinder intake manifold or exhaust manifold of a vehicle engine, the method comprising: acquiring a set of pressure data points indicative of the pressure in the cylinder intake manifold or exhaust manifold for crankshaft angular positions covering crankshaft angular rotation degrees such that each of the at least one valve has opened at least one time; and determining at least one test value based on the set of pressure data points, wherein a valve leakage is detected based on a comparison of the at least one test value to a threshold value.

A method for verifying a CVVD location learning result may include performing a learning value verification control by confirming a position of a control shaft connected to a motor with a signal value of an auxiliary cam sensor for a rotation of a camshaft if a controller determines that a learning value acquired in a short duration and a long duration of a CVVD system is desired to be verified.

A method for adjusting a valve lash in an internal combustion engine includes receiving a first signal generated by a sensor secured to the internal combustion engine, the first signal being indicative of a closing of a valve, receiving a second signal indicative of at least one of an engine speed of the internal combustion engine or a position of a camshaft of the internal combustion engine, and automatically determining an adjusted amount of lash associated with the valve based on the received first signal and the received second signal. The method also includes comparing the adjusted amount of lash to at least one predetermined threshold, and providing, in response to determining that the adjusted amount of lash is greater than the at least one predetermined threshold, a valve lash re-adjustment notification.

Various embodiments include a method for detecting deviations occurring in the valve drive of an internal combustion engine comprising: measuring dynamic pressure oscillations of intake air in an air intake tract of respective internal combustion engine during operation; calculating an inlet valve stroke phase difference and/or an outlet valve stroke phase difference based on the measured dynamic pressure oscillation; calculating a valve stroke phase deviation value with respect to a valve stroke phase reference value based on the calculated phase difference; and calculating a first valve drive deviation value based on the valve stroke phase deviation value.

A method of continuously variable valve duration (CVVD) location learning may include when a controller determines necessity of position learning for short duration and long duration of a CVVD system, performing conditional application re-learning control in which the position learning is performed in a situation in which validity determination of system environment condition for CVVD hardware and validity determination of vehicle environment condition for engine operation information of an engine are satisfied.

A method for detecting valve leakage of a least one valve at a cylinder intake manifold or exhaust manifold of a vehicle engine, the method comprising: acquiring a set of pressure data points indicative of the pressure in the cylinder intake manifold or exhaust manifold for crankshaft angular positions covering crankshaft angular rotation degrees such that each of the at least one valve has opened at least one time; and determining at least one test value based on the set of pressure data points, wherein a valve leakage is detected based on a comparison of the at least one test value to a threshold value.

Various embodiments include a method for actuating a camshaft adjuster of an internal combustion engine, in which a current is generated in an electric motor of the camshaft adjuster comprising: measuring an instantaneous strength of the current; calculating a mean value of the measured strength of the current over a predefined elapsed time; measuring a temperature of the camshaft adjuster; comparing the mean value of the measured strength of the current to a threshold value obtained from a characteristic diagram stored in a memory based on the measured temperature and the predefined elapsed time; and reducing the current if the calculated mean value of the strength of the current is higher than the threshold value.

Systems and methods for unsticking intake and exhaust valves of an engine are described. In one example, valves that may be adjustably timed relative to an engine crankshaft position may be adjusted to unstick intake and/or exhaust valve that are stuck open or closed. In addition, fuel injection timing and spark timing may be adjusted in an effort to unstick intake and/or exhaust valves.