Systems and methods for stopping an engine of a vehicle are described. In one example, the method anticipates when an engine is expected to stop and modifies engine operation so that less fuel is in the engine's intake ports when the engine is stopped so that the fuel may not escape the engine when the engine is restarted.

A stop/start system and method for an engine of a vehicle include a valve control system configured for full lift control of respective intake and exhaust valves of a plurality of cylinders of the engine and a controller of the engine configured to perform an engine stop event including initiating a fuel shutoff (FSO) event whereby fueling to the engine is disabled and the engine fully stops after a stop period and, in response to initiating the FSO event, commanding the valve control system to close each intake valve prior to closing its respective exhaust valve to (i) expel any residual gases from the cylinders during respective exhaust strokes prior to closing the respective exhaust valves, and (ii) prevent air-only intake and compression within the cylinders during the stop period to thereby mitigate or eliminate noise/vibration/harshness (NVH) caused by the air-only intake and compression.

A method includes determining a value of an operational motor current limit and setting a value of a startup current limit equal to a predetermined value in excess of the value of the operational motor current limit if a set of predetermined conditions is satisfied. The method includes determining that operation of the engine has been interrupted, operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the startup current limit after determining that operation of the engine has been interrupted, determining that operation of the engine has resumed, and operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the operational motor current limit after determining that operation of the engine has resumed.

Systems and methods for preparing an engine for a cold start are described. In one example, the air is injected into one or more pre-chambers of engine cylinders in response to an engine start request so that one or more cylinders may be heated before the engine is started. The engine may or may not be rotated while air is being injected to pre-chambers of engine cylinders.

A method includes determining a value of an operational motor current limit and setting a value of a startup current limit equal to a predetermined value in excess of the value of the operational motor current limit if a set of predetermined conditions is satisfied. The method includes determining that operation of the engine has been interrupted, operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the startup current limit after determining that operation of the engine has been interrupted, determining that operation of the engine has resumed, and operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the operational motor current limit after determining that operation of the engine has resumed.

A method includes determining a value of an operational motor current limit and setting a value of a startup current limit equal to a predetermined value in excess of the value of the operational motor current limit if a set of predetermined conditions is satisfied. The method includes determining that operation of the engine has been interrupted, operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the startup current limit after determining that operation of the engine has been interrupted, determining that operation of the engine has resumed, and operating the electric motor of the variable valve timing mechanism with a current having a magnitude that is less than or equal to the operational motor current limit after determining that operation of the engine has resumed.

In a vehicle control device with an automatic engine stop function, when the engine is in a non-operating state and the shift lever is operated to the parking range, the engine is controlled to start to supply operating oil to a valve timing changing means. The valve timing changing means is thereupon caused to change the intake valve close timing (IVC) to a predetermined advance angle position and subsequently locked thereat. The engine is then controlled to stop.

In a vehicle control device with an automatic engine stop function, when the engine is in a non-operating state and the shift lever is operated to the parking range, the engine is controlled to start to supply operating oil to a valve timing changing means. The valve timing changing means is thereupon caused to change the intake valve close timing (IVC) to a predetermined advance angle position and subsequently locked thereat. The engine is then controlled to stop.

A closing fork and open spring bias of a center power valve for a hitless control of an adjustable exhaust port 2-stroke motorcycle engine includes a closing fork which includes a flat plate that extends into two substantially parallel flat closing fork arms. An internal closing fork base section cylindrical wall accepts a shaft inserted there through. Each torsion spring of two torsion springs has a first extended leg including an approximately 90-degree bend about where the first extended leg extends out from a spring body of each torsion spring and a second leg extending straight out of a body of each torsion spring. Each of the torsion springs is a mirror of each other where the first extended leg extends from a different side. An upgrade kit and a method to convert a power valve system 2-stroke motorcycle engine to a hitless operation are also described.

An internal combustion engine is provided with a DOHC-type valve train in a cylinder head. The valve train includes an intake side camshaft with an intake side driven gear, and an exhaust side camshaft with an exhaust side driven gear. The cylinder head supports therein a spindle with an idle gear with an idle chain sprocket fixed thereto. The idle gear is in meshing engagement with both the intake and exhaust side driven gears. Rotary power of a crankshaft is transmitted via a cam chain to the idle gear to rotate both the intake and exhaust side camshafts. These camshafts are supported by bearings of a bearing wall and a camshaft holder. These bearings and camshaft holder are located, for compact arrangement, at a position axially coinciding or overlapping with the idle chain sprocket.