Disclosed is a method for detecting physical stoppage of an internal combustion engine, including: at least four cylinders, a set of cylinder pressure sensors, configured such that, over the course of a combustion cycle of the engine, there is at least one cylinder in the compression or expansion phase whose pressure is measured by a pressure sensor of the set, the method including the following steps: measuring the pressure in a cylinder in the compression or expansion phase, calculating, from the pressure measured in the cylinder, a ratio between a pressure variation in the cylinder and the pressure in the cylinder, and detecting a physical stoppage of the engine if the measured pressure is decreasing and if the calculated ratio is constant.

Disclosed is a method for detecting physical stoppage of an internal combustion engine, including: at least four cylinders, a set of cylinder pressure sensors, configured such that, over the course of a combustion cycle of the engine, there is at least one cylinder in the compression or expansion phase whose pressure is measured by a pressure sensor of the set, the method including the following steps: measuring the pressure in a cylinder in the compression or expansion phase, calculating, from the pressure measured in the cylinder, a ratio between a pressure variation in the cylinder and the pressure in the cylinder, and detecting a physical stoppage of the engine if the measured pressure is decreasing and if the calculated ratio is constant.

An engine diagnostic system is provided for diagnosing a deterioration degree of an engine mounted on a vehicle. The engine diagnostic system learns, as a knock learning value, a maximum advancement amount of an ignition timing that reduces knocking. A database stores time-series data of the knock learning value of the engine for each individual engine. The knock learning value is acquired from each of a plurality of vehicles of the same model. An evaluation process computes an evaluation value indicating the deterioration degree of a designated engine using the time-series data of the knock learning value of each engine stored in the database.

An engine diagnostic system is provided for diagnosing a deterioration degree of an engine mounted on a vehicle. The engine diagnostic system learns, as a knock learning value, a maximum advancement amount of an ignition timing that reduces knocking. A database stores time-series data of the knock learning value of the engine for each individual engine. The knock learning value is acquired from each of a plurality of vehicles of the same model. An evaluation process computes an evaluation value indicating the deterioration degree of a designated engine using the time-series data of the knock learning value of each engine stored in the database.

In various aspects, internal combustion engines, engine controllers and methods of controlling engines are described. The engine includes a camshaft and a two cylinder sets. Cylinders in the first are deactivatable and cylinders in the second set may be fired at high or low output levels. The air charge for each fired working cycle is set based on whether a high or low torque output is selected. In some implementations, the camshaft is axially shiftable between first and second positions. First cam lobes are configured to cause their associated cylinders to intake a large air charge during intake strokes that occur when the camshaft is in the first position. Second cam lobes for cylinders in the second set cause their associated cylinders to intake a smaller air charge when the camshaft is in the second position. Second cam lobes for cylinders in the first set deactivate their associated cylinders.

In various aspects, internal combustion engines, engine controllers and methods of controlling engines are described. The engine includes a camshaft and a two cylinder sets. Cylinders in the first are deactivatable and cylinders in the second set may be fired at high or low output levels. The air charge for each fired working cycle is set based on whether a high or low torque output is selected. In some implementations, the camshaft is axially shiftable between first and second positions. First cam lobes are configured to cause their associated cylinders to intake a large air charge during intake strokes that occur when the camshaft is in the first position. Second cam lobes for cylinders in the second set cause their associated cylinders to intake a smaller air charge when the camshaft is in the second position. Second cam lobes for cylinders in the first set deactivate their associated cylinders.

Various systems and methods are provided for identifying cylinder knock. In one example, cylinder knock may be identified based on a knock monitor that identifies knock based on output from a crankshaft speed sensor.

Various systems and methods are provided for identifying cylinder knock. In one example, cylinder knock may be identified based on a knock monitor that identifies knock based on output from a crankshaft speed sensor.

A method of implementing control logic of a compression ignition engine is provided. The engine includes an injector, a variable valve operating mechanism, an ignition plug, at least one sensor, and a processor. The processor outputs the signal to the ignition plug in a specific operating state so that unburnt mixture gas combusts by self ignition after the ignition plug ignites the mixture gas inside a combustion chamber. The method includes determining a geometric compression ratio of the engine, and determining control logic defining a valve opening angle CA of an intake valve. The valve opening angle CA (deg) is determined so that the following expression is satisfied, if the geometric compression ratio is <14, 40+800+DCA60550+D. Here, D is a correction term according to the engine speed NE (rpm), D=3.310.sup.10NE.sup.31.010.sup.6NE.sup.2+7.010.sup.4NE.

A method of implementing control logic of a compression ignition engine is provided. The engine includes an injector, a variable valve operating mechanism, an ignition plug, at least one sensor, and a processor. The processor outputs the signal to the ignition plug in a specific operating state so that unburnt mixture gas combusts by self ignition after the ignition plug ignites the mixture gas inside a combustion chamber. The method includes determining a geometric compression ratio of the engine, and determining control logic defining a valve opening angle CA of an intake valve. The valve opening angle CA (deg) is determined so that the following expression is satisfied, if the geometric compression ratio is <14, 40+800+DCA60550+D. Here, D is a correction term according to the engine speed NE (rpm), D=3.310.sup.10NE.sup.31.010.sup.6NE.sup.2+7.010.sup.4NE.