Systems and methods for operating an engine with an oil pump that supplies engine oil to various oil consumers in an engine are presented. In one example, a displacement of a variable displacement engine oil pump is adjusted to provide sufficient oil pressure throughout the engine, but low enough to conserve fuel.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, estimates of engine fuel consumption for operating the engine with a plurality of cylinder modes or patterns while a transmission is engaged in different gears are determined and are used as a basis for deactivating engine cylinders.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, mode changes between deactivating cylinders is based on an amount of time a valve is deactivated, and the longer the valve is deactivated the sooner cylinder valves may be deactivated. If the amount of time the valve is deactivated is short, the time that valves may be deactivated may be delayed.

Systems and methods for operating an engine with deactivating valves are presented. In one example, deactivated valves may be reactivated to increase a rate of camshaft phase indexing relative to engine crankshaft position. However, if a desired rate of camshaft indexing is low, the engine cylinders may remain deactivated based on the low rate of desired camshaft indexing.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, engine volumetric efficiency actuators are adjusted in response to a request to activate engine cylinders so that engine intake manifold pressure is drawn down quickly toward its normal state at the engine's present speed and torque.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, valves of a cylinder are deactivated in a closed state in response to an indication of degradation of a valve of the cylinder. Further, fuel flow to the cylinder may be stopped via ceasing to inject fuel to the cylinder.

Systems and methods for operating an engine with deactivating and non-deactivating valves is presented. In one example, the engine may include non-deactivating intake valves, deactivating intake valves, and only non-deactivating exhaust valves. The non-deactivating exhaust valves may operate to open and close during an engine cycle while deactivating intake valves remain closed during the engine cycle to prevent air flow through selected engine cylinders.

A method of providing diagnostic information for an electromagnetic latch assembly (122) includes providing a pulse to a circuit (200) that include one or more electromagnetic latch assemblies. The circuit (200) includes coils (199) of the electromagnetic latch assemblies. Each coil is inductively coupled with an armature (131) that is mechanically coupled to a latch pin (118). The circuit (200) is pulsed and a DC current in the circuit (200) that results from the pulse is measured over a first interval to determine a primary response. The current in the circuit (200) over a second interval is measured to determine a reference response. A second pulse may be used to generate the current for the reference response. The primary response and the reference response are compared to provide diagnostic information relating to position or movement of one or more of the latch pins (118).

A valvetrain includes a rocker arm assembly having a rocker arm and an electromagnetic latch assembly. An electromagnet of the latch assembly is housed within a chamber formed by the rocker arm. Passageways suitable for oil cooling of the electromagnet are formed through and inside the rocker arm. In some embodiments, oil for cooling is supplied through a pivot. In some embodiments, oil for cooling is obtained from oil splash. Oil cooling may allow modes of operation such as of dynamic cylinder deactivation and dynamic variable valve actuation to be used without overheating the electromagnet.

A variable valve mechanism includes an input arm that axially supports a roller pressed by a cam, via a roller pin, an output arm that drives a valve when swinging, a switch device that switches the variable valve mechanism between a coupled state where the both arms are coupled and an uncoupled state where the arms are uncoupled from each other, and a lost motion spring that biases the roller against the cam when in the uncoupled state. The lost motion spring includes an extended portion extending in an inter-arm clearance between the input arm and the output arm. An end of the roller pin projects from the input arm into the inter-arm clearance by such a length that the end is accommodated in the inter-arm clearance and that allows a spring retaining portion to be formed in the end. The spring retaining portion is formed in the end.