A method for diagnosing an engine system including a continuous variable valve duration (CVVD) apparatus, a driving unit of the CVVD apparatus including a first driving unit and a second driving unit, a CVVD position detector configured to detect a position of the CVVD apparatus, a camshaft position detector configured to detect a position of a camshaft, a front lambda detector configured to detect a lambda value at front of intake valve, and a controller may include the steps of starting the engine, detecting measured values of the front lambda detector during combustion of first to fourth cylinders (first to fourth lambda values), determining whether CVVD driving unit is misaligned according to the detected first to fourth lambda values, and generating a warning notification when the CVVD driving unit is determined to be misaligned.

Methods and systems are provided for a phase control apparatus in a variable cam timing (VCT) system of an engine, the phase control apparatus having a locked configuration where a locking pin coupled to a first vane of the vane rotor is engaged with a locking pin recess in a cover plate of the phase control apparatus. In one example, the phase control apparatus includes a rubber or plastic isolator pad positioned in a recess in a wall adjacent to the first vane such that when the vane rotor is rotated to the locked configuration, the first vane contacts the isolator pad before it can strike the housing. The isolator pad serves to maintain the gap between the first vane and the housing, and also reduces the likelihood of other vanes of the vane rotor from striking the housing.

A decompression pin is inserted into a swing range of an end portion of a rocker arm, on a side which is supported by a lash adjuster, when the rocker arm has been inclined toward a direction in which a valve is opened. The decompression pin comes into contact with the end portion of the rocker arm when the rocker arm is inclined toward a direction in which the valve is closed, and thereby restricts the rocker arm from returning to a position at which the valve is completely closed, and the valve becomes in a slightly opened state even in a compression stroke.

Provided is a control device for controlling an internal combustion engine including a fuel injection valve, an ignition device, and a variable valve operating device configured to switch between a base opening/closing mode of an intake valve and a continuous valve opening mode. The control device is configured to execute a cold start control at a cold start. The cold start control includes: a startability improvement processing executed in a predetermined number of cycles after the start of cranking; and a combustion start processing executed after this predetermined number of cycles. In the startability improvement processing, the continuous valve opening mode is selected in at least an expansion stroke and an exhaust stroke, and fuel injection is executed without ignition. In the combustion start processing, the base opening/closing mode is selected continuously during one cycle, and ignition is executed.

Disclosed is a method for determining the state of rotation of a camshaft of a vehicle engine, notable in that the method for determining the state of rotation of the camshaft determines that the state of rotation of the camshaft is in the process of stalling, corresponding to an intermediate state of rotation, when the time elapsed since the last detection of a camshaft wheel tooth-front by the sensor exceeds Tcam_cal, Tcam_cal being defined as the theoretical length of time needed for the camshaft wheel to cover an angular distance equal to the maximum angular distance separating two successive camshaft wheel tooth-fronts at a camshaft rotational speed corresponding to a predetermined low engine speed higher than the minimum engine speed tolerated by the engine.

A method for controlling intake and exhaust valves of an engine may include: determining, by a controller, a target opening duration of the intake and exhaust valves based on an engine load and an engine speed; modifying, by an intake continuous variable valve duration (CVVD) device and by an exhaust CVVD device, current opening and closing timings of the intake valve and/or exhaust valve based on the target opening duration of the valves; and advancing or retarding, by the intake and/or exhaust CVVD devices, the current opening timing of the intake and exhaust valves while simultaneously retarding or advancing the current closing timing of the intake and exhaust valve by a predetermined value based on the target opening duration.

A controller for an internal combustion engine includes: a failure determination section which determines a failure state in a case where a relative rotation phase of an intake side valve opening and closing timing control mechanism does not change when controlling the mechanism after starting the driving of a starter motor and trying to change the relative rotation phase of the mechanism in a start control for starting an internal combustion engine. When the section determines a failure, the controller performs at least one of an intake air amount increase control in which an opening degree of a throttle valve is increased, an ignition timing advance angle control in which injection of fuel is performed at a timing earlier than a set timing and ignition is performed, and a multi-injection control in which the fuel is injected immediately before the ignition in addition to the fuel injection in an intake stroke.

A method of operating a cam shaft phaser including a stator including a radially inwardly extending protrusion, a rotor including a radially outwardly extending protrusion and a slot in the radially outwardly extending protrusion, a cover non-rotatably connected to the stator, a chamber circumferentially bounded by the radially inwardly extending protrusion and the radially outwardly extending protrusion, a pin disposed in the slot, and a first channel connecting the chamber with the slot. The method comprises: blocking, with the locking pin, rotation of the rotor with respect to the stator; applying pulse width modulation voltage to a control valve as a non-rectangular wave form; flowing fluid from the control valve to the chamber; flowing the fluid through the first channel to the slot; axially displacing the locking pin with the fluid; disengaging the locking pin from the cover; and rotating the rotor with respect to the stator.

A method of continuously variable valve duration (CVVD) location learning may include when current position information applied to valve duration control in a CVVD system is not detected by a controller, executing a re-learning mode in which re-learning of short duration and long duration is performed by classifying a situation, in which the current position information is not detected, into a plurality of non-detection situations.

Aspects of the present disclosure are directed to valve clearance adjustment systems and related methods that can be used to quickly and easily establish and accurately fix a desired gap between valve stems and associated valve adjustment screws attached to rocker arms, such as may be used with intake valves, exhaust valves, and fuel-injection mechanisms, among others, within, e.g., an internal combustion engine. Various alternative implementations and related methods are provided.