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 and systems are provided for reducing air flow to an emission control device during a fuel shut-off event. In one example, a method may include adjusting a timing of an exhaust valve and a timing of an intake valve of a cylinder during the fuel shut-off event using a common actuator. The actuator may include a planetary gear system configured to rotate a first portion of a camshaft in a first direction and a second portion of the camshaft in a second, opposite direction.

A camshaft may include a shaft on which at least one sliding element is received in such a way as to be axially displaceable along a shaft axis. The shaft may comprise an external longitudinal spline structure that meshes with an internal spline structure of a passage in the sliding element such that the sliding element is arranged in a rotationally fixed manner on the shaft. The sliding element, on its axial end faces, may comprise guiding portions by way of which the sliding element is guided on the shaft to minimize an axial offset of the sliding element. Further, guiding sleeves against which the guiding portions of the sliding element are supported may be received on the shaft.

A method for mounting a camshaft module may involve a module that includes a module cover in which a camshaft is accommodated. The camshaft may comprise a main shaft and a plurality of displacement elements with cam tracks formed thereon for valve-control purposes. The displacement elements may be arranged at predetermined positions in the module cover. The main shaft may be guided along a shaft axis through accommodating passages of the displacement elements. The method may involve arranging a first displacement element in the module cover, introducing the main shaft into the module cover and guiding the main shaft through the accommodating passage of the first displacement element, arranging a second displacement element in the module cover, rotating the main shaft about the shaft axis by an angular amount, and advancing and guiding the main shaft through the accommodating passage of the second displacement element. Further, the displacement elements are arranged in the model cover with an identical rotary orientation about the shaft axis.

A variable valve driving mechanism of an engine includes a rocker arm configured to control open and close of a valve and a servo rocker arm arranged in parallel to the rocker arm. A swing end of the servo rocker arm extends to the top of the swing end of the rocker arm. A valve adjustment gap provided in the swing direction of the servo rocker arm and the rocker arm is formed between the servo rocker arm and the rocker arm. A gap compensating device telescopically filling the valve adjustment gap and configured to adjust the valve to be delayed to close or open in advance when extending to the valve adjustment gap is provided between the servo rocker arm and the rocker arm.

A rocker arm assembly includes an outer arm having a first outer side arm and a second outer side arm, each of the first and second outer side arms having a low lift lobe contacting surface, an inner arm having a high lift lobe contacting surface and disposed between the first and second outer side arms, the inner arm having a first end and a second end operably associated with a lash adjuster and defining a latch bore, and a latch assembly arranged at least partially within the latch bore. The latch assembly is movable between a first configuration and a second configuration. In the first configuration, the latch assembly engages the outer arm such that the outer arm rotates with the inner arm, and in the second configuration, the latch assembly disengages the outer arm such that the outer arm rotates independently from the inner arm.

A variable valve lift apparatus includes an outer body for selectively performing a first lever motion depending on a rotation of a high cam, the outer body further forming an inside space, an inner body disposed in the inside space of the outer body so as to selectively perform a second lever motion depending on a rotation of the high cam by being selectively locked to the outer body, the selective performing of the second lever motion depending on a rotation of a low cam being released from the outer body, and the inner body being configured so that a valve is connected with one end of the inner body, a connecting shaft rotatably connecting the outer body with the inner body, and a lost motion spring wound around the connecting shaft so as to return the outer body after being relatively rotated with respect to the inner body when the outer body is released from the inner body, wherein a roller rolling-contacting with the low cam is disposed at the inner body, and the connecting shaft is disposed between a pivot axis for a lever motion of the inner body and the roller.

In a lean-burn engine equipped with a turbocharger, a responsiveness of a super-charging pressure in a lean region is enhanced by control of a valve timing of an exhaust valve while a combustion state is restrained from varying. A variable valve mechanism that can change an opening timing of the exhaust valve while keeping a closing timing of the exhaust valve constant, is included in the lean-burn engine. When a target operation point is located in the lean region, and when an actual supercharging pressure is lower than a target supercharging pressure, supercharging pressure increasing control that advances the opening timing while keeping the closing timing constant is executed by operating the variable valve mechanism.

A valve gear for an engine includes a camshaft including a cam, a rocker shaft, and a first rocker arm which swings when pressed by the cam. The valve gear includes a spring, which biases the first rocker arm and a second rocker arm which presses an intake valve or an exhaust valve, in a return direction. The valve gear includes a first pin hole of the first rocker arm, a second pin hole and a third pin hole of the second rocker arm, a first switch pin, a second switch pin, a third switch pin, and a switch which switches between a connected state and a non-connected state of the switch pins. The second rocker arm includes a stopper against which the first rocker arm abuts. When the first rocker arm abuts against the stopper, all of the pin holes are located on the same axis.

A switching rocker arm assembly can include an outer arm having a first outer side arm and a second outer side arm, each of the first and second outer side arms having a high lift lobe contacting surface, and an inner arm disposed between the first and second outer side arms and pivotably secured to the outer arm, the inner arm having a low lift lobe contacting surface and defining a latch bore. A latch assembly can be arranged at least partially within the latch bore of the inner arm. The latch assembly can include a latch pin having an orientation pin receiving recess, a sleeve engaging the latch pin and having an orientation pin opening, and an orientation pin extending through the orientation pin opening into the orientation pin receiving recess. The orientation pin can have a substantially cylindrical first wall and a substantially cylindrical second wall.