Methods and systems are provided for diagnosing whether active engine mounts configured to isolate engine vibration from a cabin and chassis of a vehicle are functioning as desired. In one example, a method includes indicating degradation of an active engine mount by inducing degraded combustion events in a preselected engine cylinder, and operating the active engine mount in multiple modes, the indication responsive to an amount of vehicle chassis vibration during each of the modes. By monitoring chassis vibrations as a function of induced degraded combustion events, and further responsive to the active engine mounts being controlled to the multiple modes, it may be indicated as to whether the active engine mounts are functioning as desired.

A method for controlling the operation of a spark ignition internal combustion engine is described. The engine includes: a combustion chamber, an intake duct for placing the combustion chamber in communication with the external, a throttle valve arranged inside the intake duct, a carburetor for introducing fuel into the intake duct to form an air/fuel mixture to be intaken into the combustion chamber, and a spark plug arranged inside the combustion chamber to generate a spark for igniting the combustion of the air/fuel mixture. The method includes: monitoring the opening degree of the throttle valve; monitoring the speed of the engine, preventing the spark plug from generating the spark, if the opening degree of the throttle valve drops below a first opening degree threshold value and the speed of the engine is greater than a first engine speed threshold value.

When the concentration of alcohol is high, the timing of ignition is controlled upon the lapse of a delay time Tig from a reference timing t as a timing when a reference angle ref that is more advanced than a top dead center is detected. It should be noted, however, that the timing of ignition is controlled to a timing when a retarded angle aop is detected, if it is determined that a misfire has occurred.

A controller for an internal combustion engine includes processing circuitry configured to execute: a dither control process of operating fuel injection valves to designate at least one of cylinders as a lean combustion cylinder, in which an air-fuel ratio is leaner than a stoichiometric air-fuel ratio, and to designate at least another one of the cylinders as a rich combustion cylinder, in which an air-fuel ratio is richer than the stoichiometric air-fuel ratio; and an idle-time limiting process of causing an absolute value of a difference between the air-fuel ratio in the lean combustion cylinder and the air-fuel ratio in the rich combustion cylinder to be smaller when the internal combustion engine is idling than when the internal combustion engine is not idling.

A pre-stoppage ignition control unit defines, as a stoppage transition air amount, an intake air amount of the engine with which the engine torque becomes the stoppage transition torque in a state in which an ignition timing of the engine is set to a predetermined self-sustaining operation ignition timing, defines, as an intermediate timing, a predetermined timing earlier than timing at which the intake air amount converges to the stoppage transition air amount during an execution period of the pre-stoppage self-sustaining operation control, sets the ignition timing of the engine in a period from the start of the pre-stoppage self-sustaining operation control to the intermediate timing to timing earlier than the self-sustaining operation ignition timing, and sets the ignition timing of the engine in the period after the intermediate timing to the self-sustaining operation ignition timing.

Methods and systems are provided for adjusting noise, vibration, and harshness (NVH) limits for a vehicle based on a number of occupants in the vehicle. In one example, a method may include responsive to detecting zero occupants, reducing NVH constraints for operating the vehicle and adjusting one or more vehicle operating parameters based on the reduced NVH constraints.

A valve opening and closing timing control apparatus includes a valve opening and closing timing control apparatus provided at a camshaft for an intake valve of an internal combustion engine and a valve opening and closing timing control apparatus provided at a camshaft for an exhaust valve and includes a control unit changing a phase of one of the valve opening and closing timing control apparatus for the intake valve and the valve opening and closing timing control apparatus for the exhaust valve serving as an electric type which malfunctions to a most advanced angle phase and changing a phase of the other of the valve opening and closing timing control apparatus which is inhibited from malfunctioning to an advanced angle side in a case where one of the valve opening and closing timing control apparatus serving as the electric type malfunctions.

A waste gate valve (7) of a turbocharger (3) is fully opened during idling after warm-up is completed in order to reduce exhaust resistance. However, during idling in an engine cold state when a cooling water temperature (TW) is below a threshold value (TW1), the waste gate valve (7) is open-loop controlled to an intermediate opening degree that is smaller than full opening. An ignition timing is delayed (retarded) for catalyst warm-up. When the cooling water temperature (TW) reaches (t3) the threshold value (TW1), the opening degree of the waste gate valve (7) is set to full opening. When an accelerator opening degree (APO) becomes large (t4) before warm-up is completed, the limitation of the opening degree is released.

When a request for temperature increase of a three-way catalyst is made, a CPU executes dither control in which one of a plurality of cylinders is set as a rich combustion cylinder with a richer air-fuel ratio than a stoichiometric air-fuel ratio and the remaining cylinders are set as lean combustion cylinders with a leaner air-fuel ratio than the stoichiometric air-fuel ratio. When not executing the dither control, the CPU learns a rich learning value that is a learning value of a degree of a rich imbalance based on an upstream-side air-fuel ratio. When the rich learning value is greater than or equal to a predetermined value, the CPU prohibits the dither control.

Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, values of an engine spark to engine torque relationship are adjusted to improve engine torque control. The engine is subsequently operated responsive to adjusted values of the engine spark to engine torque relationship.