Methods and systems are provided for operating an engine to diagnose and compensate for cylinder imbalance in an engine. In one example, a method may include diagnosing a torque imbalance in a multi-cylinder engine by operating the engine at a lean air-fuel ratio (AFR) while an amount of ammonia stored in an selective catalytic reduction (SCR) system is greater than a threshold amount and a temperature of the engine is greater than a threshold temperature; and responsive to the diagnosed torque imbalance, adjusting fueling and spark timing for each cylinder, the adjustments based on an AFR offset of each cylinder determined while adjusting the lean AFR.

Methods and systems are provided for expediting emission control device heating. In one example, a method may include flowing air from an intake of an engine to one or more emission control devices via an air injection system while operating a turbocharger via an electric motor to maintain a desired airflow to the engine in response to an emission control device heating condition. In this way, fresh air is provided to the one or more emission control devices without degrading engine performance or increasing engine speed.

Example methods and systems for treating exhaust from an internal combustion engine may generally determine a catalytic converter in an exhaust system is at least partially deactivated by detecting an elevated exhaust temperature and a lean-burn operating condition. In response, a deactivation level of the catalytic converter may be determined, which may be compared with a threshold deactivation level. A magnitude of a temporary rich-fuel operating condition as a response may be determined based upon the comparison. The catalytic converter may be reactivated with the temporary rich-fuel operating condition.

A control device (40) is connected to a differential pressure sensor (41), a navigation system (42), and a fuel injection valve (17). The control device (40) is configured to: execute a regeneration control of monitoring a purification situation (C1) and supplying unburned fuel (F2), which is injected from the fuel injection valve (17) and does not contribute to driving, to an exhaust gas purification system (20) in a case where the purification situation (C1) becomes a deteriorated situation (Ca); and execute a control of monitoring a road situation (C2) and stopping the regeneration control before the road situation (C2) actually becomes an accelerator off situation (Cb) in which an accelerator opening degree (1) of an accelerator pedal (43) becomes off.

A controller executes a fuel introduction process of introducing, in a state in which the crankshaft of an internal combustion engine is rotating, air-fuel mixture that contains fuel injected by a fuel injection valve into the exhaust passage without burning the air-fuel mixture in the cylinder. The controller executes a discharge process of performing spark discharge of an ignition plug at non-combustion ignition timing during the execution of the fuel introduction process. The non-combustion ignition timing is timing within a period in which the air-fuel mixture is not burned in the cylinder even if the spark discharge of the ignition plug is performed.

In some examples, a system including one or more processors may receive sensor data from one or more sensors indicating one or more engine parameters of an engine including a combustion chamber. Based on the sensor data, the system may determine a homogeneity index indicative of a homogeneity of an air-fuel mixture within the combustion chamber. Furthermore, the system may determine an estimated amount of NOx in the exhaust gas based at least in part on the homogeneity index. In addition, based at least partially on the estimated amount of NOx in the exhaust gas, the system may send an instruction to control an engine component.

A hybrid vehicle includes: an internal combustion engine; a rotating electric machine; a planetary gear mechanism to which the internal combustion engine, the rotating electric machine and an output shaft are connected; a catalyst that purifies exhaust gas of the internal combustion engine; and a controller that controls the internal combustion engine and the rotating electric machine. The controller controls the internal combustion engine and the rotating electric machine to perform catalyst temperature control to shift an operating point on a map representing a relationship between rotation speed of the internal combustion engine and torque generated by the internal combustion engine so that the catalyst has a temperature within an appropriate temperature range. Degradation of the catalyst can be suppressed without deteriorating the function of the catalyst.

An exhaust purification system of an internal combustion engine includes a catalyst arranged in an exhaust passage of the internal combustion engine, a fuel supply device supplying fuel to the catalyst through the exhaust passage, and a control device configured to control the supply of fuel by the fuel supply device. The control device is configured to calculate a concentration in exhaust gas of fuel supplied to the exhaust passage by the fuel supply device and a saturation vapor pressure concentration of the fuel and supply fuel from the fuel supply device to the catalyst only when the concentration in the exhaust gas is higher than the saturation vapor pressure concentration.

The present invention provides a catalyst diagnosis device that enables precisely grasping a variation of AFR and diagnosing a deteriorated condition of the catalyst based on the variation. A timer counts elapsed time Tosc until downstream AFU (AFRd) meets a predetermined threshold condition when the fuel injection quantity is corrected by increasing or decreasing it so that as to the AFRu, the transition from either of leanness or richness to the other is repeated with the stoichiometric area between the leanness and the richness. An OSA calculating section calculates an Oxygen Storage Amount (OSA) as a function of the AFR, Mfuel, Ne and Tosa. An OPA calculating section calculates an Oxygen Purge Amount (OPA) as a function of the AFR, Mfuel, Ne and Topa. A deterioration diagnosing section diagnoses a deteriorated condition of the catalyst C on the basis of at least one of the OSA and OPA.

A method of increasing parasitic load on an internal combustion engine includes injecting a fuel into a combustion chamber of an active cylinder of the internal combustion engine, combusting the injected fuel in the combustion chamber of the active cylinder, and determining that increasing a temperature of an exhaust aftertreatment device is required. The method includes increasing a parasitic load on the internal combustion engine by deactivating a cylinder, wherein no fuel is injected in the deactivated cylinder for a combustion cycle of the internal combustion engine, and further increasing the parasitic load by pulsing a spill valve member of a spill valve of a fuel injector in the deactivated cylinder between a fully closed position and an at least partially open position.