The present invention relates generally to techniques for improving fuel efficiency of a vehicle powered by an internal combustion engine capable of operating at various displacement levels. An autonomous driving unit or cruise controller selects when possible an engine torque output that corresponds to a fuel efficient displacement level. The resultant vehicle speed profile and NVH level is acceptable to vehicle occupants.

Methods and systems are provided for reducing or avoiding a torque bump resulting from unintended combustion in a deactivated cylinder of a variable displacement engine. In one example, a method includes reducing or avoiding a torque bump associated with an engine of a vehicle while one or more cylinders of the engine are deactivated by reducing a torque output of the engine by an amount substantially equivalent to a torque increase provided to the engine via the unintended combustion event. In this way, undesired torque bumps may be avoided when operating in VDE mode, which may improve customer satisfaction, and which may enable improved fuel economy and engine efficiency.

A control device for the selective control of a multiplicity of actuators of an internal combustion engine is provided. The control device includes a central control unit, and a multiplicity of actuators associated with the multiplicity of actuator controls, which are connected to the central control unit. Each actuator control, of the multiplicity of actuator controls, includes an address, so that the actuator controls are selectively controllable by the central control unit by means of the address. Also, each actuator control includes a comparator, which is configured to compare a signal, preferably a voltage or current signal, emitted by the central control unit with the address. The comparator also emits an activation signal via an activation line, if the comparison has resulted in a match of the signal with the address of the respective actuator control within a window, preferably a voltage window (?V).

Methods and systems are provided for reducing engine torque using spark retard. In one example, a method may include calculating a spark timing for each firing event of a plurality of firing events individually in order to achieve a desired amount of reduced torque as an average torque over the plurality of firing events. An occurrence of random misfire may be reduced by rounding the spark timing for each firing event of the plurality of firing events to a stable region or a misfire region.

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.

Methods and systems are provided for reducing or avoiding a torque bump resulting from unintended combustion in a deactivated cylinder of a variable displacement engine. In one example, a method includes reducing or avoiding a torque bump associated with an engine of a vehicle while one or more cylinders of the engine are deactivated by reducing a torque output of the engine by an amount substantially equivalent to a torque increase provided to the engine via the unintended combustion event. In this way, undesired torque bumps may be avoided when operating in VDE mode, which may improve customer satisfaction, and which may enable improved fuel economy and engine efficiency.

A multi-cylinder spark-ignition internal combustion engine includes a monitored cylinder and a plurality of non-monitored cylinders, a pressure sensor disposed to monitor in-cylinder pressure in the monitored cylinder and a rotational position sensor. The controller is in communication with the pressure sensor, the rotational position sensor and the spark controller. The controller monitors, via the pressure sensor, in-cylinder pressure for the monitored cylinder during a combustion event, and determines a first spark timing based upon a desired spark timing and the in-cylinder pressure. A spark controller controls spark timing for the monitored cylinder based upon the final spark timing. The controller monitors, via the rotational position sensor, engine rotational speed and crankshaft speed pulsations associated with the monitored cylinder and the non-monitored cylinders, and determines a modal coefficient for the non-monitored cylinders based upon the engine rotational speed and the crankshaft speed pulsations.

Systems and methods for operating an engine that includes a compression ratio linkage for adjusting engine compression ratio are described. The systems and methods provide different ways of diagnosing the presence or absence of engine misfire in response to engine operating regions that may be more or less prone to torsional engine crankshaft vibration. In one example, engine misfire may be determined responsive to force applied to an engine compression ratio changing linkage.

A system includes a control system configured to monitor operating conditions in at least a first cylinder of a reciprocating engine and to control the reciprocating engine, wherein the control system includes a first sensor configured to monitor a first type of operating condition of the first cylinder, and a controller communicatively coupled with the first sensor. The controller is configured to receive a first signal indicative of a first measurement of the first type of operating condition from the first sensor; analyze the first signal to detect a misfire condition in the first cylinder; derive an amount of residual gas in the first cylinder if the misfire condition is detected; and adjust control of the reciprocating engine based on the amount of residual gas.

Methods and systems are provided for addressing spark plug soot fouling. In one example, a method may include alternating one or more combustion events with spark timing advanced with one or more combustion events with nominal spark timing. The approach allows spark plug over-heating, and related issues such as knock, to be reduced.