Methods and systems are provided for regenerating a particulate filter positioned in an exhaust system of an engine of a vehicle. In one example, a method comprises obtaining a first air flow in an intake of the engine and obtaining a second air flow in the intake of the engine, where regeneration of the particulate filter is conducted in response to the first air flow differing from the second air flow by at least a threshold amount, where the first air flow and the second air flow comprise air flow routed from the exhaust system to the intake of the engine. In this way, the particulate filter may be regenerated under conditions where a loading state of the particulate filter is not known.

Systems and methods for determining operation of a cylinder deactivating/reactivating device are disclosed. In one example, a direction of engine rotation is selected to maximize air flow through the engine while the engine is rotated without combusting air and fuel. Operation of one or more cylinder valve deactivating mechanisms is assessed while the engine is rotated without combusting air and fuel.

Methods and systems are provided for drying a wet-fouled spark plug during engine flooding conditions. In one example, a method may include, reverse rotating the engine unfueled and activating a heating element of an exhaust catalyst to flow heated ambient air through the combustion chamber to dry the wet-fouled spark plug.

When an engine is stopped, a rotational position at a time when a crankshaft starts rotating in a reverse direction is predicted based on a rotational position detected by a crank angle sensor. A target rotational position is set within a range of the crankshaft rotational position between a time when the exhaust valve of one of four cylinders in the expansion stroke when the crankshaft starts rotating in the reverse direction is opened and a time when the expansion stroke of the cylinder ends. When the predicted rotational position is behind the target rotational position, a torque applying device applies a positive rotational torque to the crankshaft. At the time when the exhaust valve of the cylinder in the expansion stroke when the crankshaft starts rotating in the reverse direction is opened, application of the positive rotational torque from the torque applying device to the crankshaft is stopped.

An engine automatic stop/restart device includes an ignition-prohibition-decision unit that prohibits an ignition for an engine, which is controlled by the ignition-control unit, when a reverse rotation of the engine is detected based on a crank-angle signal; and an ignition-prohibition-release-decision unit that releases an ignition prohibition, after the ignition is prohibited by the ignition-prohibition-decision unit; in which the ignition-prohibition-release-decision unit releases the ignition prohibition when regular rotational signals of the engine, of which count is greater than or equal to a predetermined count, is detected and an engine revolution number is greater than or equal to a predetermined revolution number, after the reverse rotation of the engine is detected, and before a crank is positioned at a compression top dead center of the engine.

Methods and systems are provided for diagnostics of a wastegate valve during vehicle-off conditions. In one example, the engine may be reverse rotated, unfueled, and air flow via the intake manifold may be estimated and compared to a baseline air flow. A stuck open wastegate valve may be indicated based on the comparison between the intake air flow and the baseline air flow.

Systems and methods for diagnosing the presence or absence of turbocharger wastegate degradation are presented. In one example, an intake manifold pressure sensor provides a basis for determining whether or not turbocharger wastegate degradation present. The turbocharged engine may be rotated in a reverse direction to assess wastegate degradation.

An engine control device includes an electronic control unit. The electronic control unit is configured to perform a spark discharge with an ignition plug for each cylinder by cutting off energization after elapse of a predetermined period from start of energization to an ignition coil for each cylinder of the engine, to stop the spark discharge caused by the ignition plug for each cylinder after supply of fuel to the engine is stopped when operation of the engine is stopped, and to control an ignition plug so as to stop the spark discharge caused by the ignition plug from a cylinder after a rotation speed of a crankshaft decreases gradually and the rotation speed of the crankshaft reaches a preset threshold value or less, after the stop of the supply of fuel to the engine.

An engine control device includes an electronic control unit. The electronic control unit is configured to perform a spark discharge with an ignition plug for each cylinder by cutting off energization after elapse of a predetermined period from start of energization to an ignition coil for each cylinder of the engine, to stop the spark discharge caused by the ignition plug for each cylinder after supply of fuel to the engine is stopped when operation of the engine is stopped, and to control an ignition plug so as to stop the spark discharge caused by the ignition plug from a cylinder after a rotation speed of a crankshaft decreases gradually and the rotation speed of the crankshaft reaches a preset threshold value or less, after the stop of the supply of fuel to the engine.

Methods and systems are provided for diagnostics of an exhaust tuning valve during vehicle-off conditions. In one example, the engine may be reverse rotated, unfueled while the position of the exhaust is varied and an intake air flow is estimated at each position of the exhaust tuning valve. The exhaust tuning valve may be diagnosed based on a change in air flow with the variation in the position of the exhaust tuning valve.