A multicylinder engine includes a plurality of intake ports, a plurality of in-cylinder injectors, and an electronic control unit. The electronic control unit is configured to initially set a value of a control parameter of the multicylinder engine, individually for each of the cylinders, such that there is a common regularity between a distribution among the cylinders, of a difference of the value of the control parameter of each of the cylinders from the value of the control parameter of a reference cylinder, and a distribution among the cylinders, of a difference of the distance of a narrowed portion of each of the cylinders from the distance of the narrowed portion of a reference cylinder. The control parameter is a parameter that determines an air-fuel ratio of an air-fuel mixture around an ignition plug at a time of ignition in stratified charge combustion operation.

A PCM (100) selects one of a CI mode or an SI mode based on the operating conditions of the engine (1). In the CI mode, the engine (1) is operated by compression ignition combustion. In the SI mode, the engine (1) is operated by spark ignition combustion. if, while the engine (1) is being operated in the CI mode, a determination is made that an estimated value (Tc) of the catalyst temperature is lower than or equal to a warming start temperature (Ts), the PCM (100) further performs first warming control to assign four cylinders (18) as CI and SI cylinders, which perform the compression ignition combustion and the spark ignition combustion, respectively, such that the four cylinders (18) alternately perform the compression ignition combustion and the spark ignition combustion in accordance with the order of combustion of the cylinders.

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.

An engine includes a cylinder body, a cylinder head, and an ignition device including spark plugs. The engine also includes an intake device connected to intake ports, an exhaust device connected to exhaust ports, pistons, and a crankshaft connected to the pistons by connecting rods. Explosion intervals of the cylinders are 270, 180, 90, and 180 as crank angles. The engine further includes a discomfort eliminator which, when the engine speed is lower than a predetermined value, makes the indicated mean effective pressure of at least one of two cylinders having an explosion interval of 90 lower than the indicated mean effective pressures of the other cylinders having an explosion interval of not 90. The engine causes unequal-interval explosions but produces little change in the driving energy per unit time during an operating state in which an occupant is liable to feel torque fluctuations.

A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines based on skip fire operation of the engine are described. In one aspect the skip fire decisions are made on a working cycle by working cycle basis. During selected skipped working cycles, the corresponding cylinders are deactivated such that air is not pumped through the cylinder during the selected skipped working cycles. In some implementations, the cylinders are deactivated by holding associated intake and exhaust valves closed such that an air charge is not present in the working chamber during the selected skipped working cycles.

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.

The presently disclosed subject matter relates to an apparatus which enables a use to easily and safely disable a vehicular variable cylinder management technology system, while enabling restoration of the VCM/ECO mode under certain vehicle-related conditions or driving conditions. The presently disclosed apparatus comprises a potentiometer capable of modifying the voltage input received by the vehicle sensors.

Systems and methods for determining when one or more cylinders of an engine may be deactivated are presented. In one example, different cylinder deactivation strategies are used to determine which engine cylinders are deactivated during an engine cycle in response to an actual total number of valve actuator state changes being greater than a first threshold.

In a control apparatus for an internal combustion engine, The ignition timing in a rich-cylinder is corrected toward a retardation side from a theoretical-MBT such that the torque generated in the rich-cylinder exceeds a torque generated in the rich-cylinder at the theoretical-MBT, and the ignition timing in a lean-cylinder is corrected toward an advancement side from the theoretical-MBT such that the torque generated in the lean-cylinder exceeds a torque generated in the lean-cylinder at the theoretical-MBT, when a temperature raising process is being executed, and the ignition timing in the rich-cylinder is corrected further toward the retardation side such that the torque generated in the rich-cylinder becomes equal to or smaller than a maximum theoretical generated torque and equal to or larger than the torque generated in the lean-cylinder at the theoretical-MBT, when the temperature raising process is being executed and the engine is in a low-load operating state.

A variety of methods, diagnostic modules and other arrangements for detecting air induction faults during operation of an internal combustion engine are described. In some embodiments, the intake manifold pressure is monitored with the intake pressure being read for each induction opportunity. Induction faults may be detected based at least in part on a comparison of the manifold pressure readings for sequential induction opportunities. In some embodiments, an induction fault is identified when the difference between the manifold pressure associated with an induction opportunity and the immediately preceding induction opportunity exceeds an induction fault threshold.