Abstract: A torque request module determines a torque request for an engine based on a driver input. A cylinder control module determines a target fraction of a total number of cylinders of the engine to be activated based on the torque request. An air fuel imbalance (AFIM) module selectively commands that the cylinder control module set the target fraction based on a predetermined fraction of the total number of cylinders of the engine to be activated. The cylinder control module further: sets the target fraction based on the predetermined fraction in response to the command; and activates and deactivates opening of intake and exhaust valves of the cylinders of the engine based on the target fraction. The AFIM module further, while the target firing fraction is set based on the predetermined fraction, selectively diagnoses the presence of an AFIM fault based on samples of a signal from an oxygen sensor.

Abstract: A torque request module determines a torque request for an engine based on a driver input. A cylinder control module determines a target fraction of a total number of cylinders of the engine to be activated based on the torque request. An air fuel imbalance (AFIM) module selectively commands that the cylinder control module set the target fraction based on a predetermined fraction of the total number of cylinders of the engine to be activated. The cylinder control module further: sets the target fraction based on the predetermined fraction in response to the command; and activates and deactivates opening of intake and exhaust valves of the cylinders of the engine based on the target fraction. The AFIM module further, while the target firing fraction is set based on the predetermined fraction, selectively diagnoses the presence of an AFIM fault based on samples of a signal from an oxygen sensor.

Abstract: An engine assembly includes a water pump assembly and an oil cooler mounted to the water pump assembly. The water pump assembly includes a rear housing which at least partially defines at least one water passage to fluidly connect the water pump assembly to the oil cooler. A surface is defined by the rear housing and corresponds to a sealing surface on the engine block such that the oil cooler and the water pump assembly are fluidly sealed to the engine block.

Abstract: An engine assembly includes a water pump assembly and an oil cooler mounted to the water pump assembly. The water pump assembly includes a rear housing which at least partially defines at least one water passage to fluidly connect the water pump assembly to the oil cooler. A surface is defined by the rear housing and corresponds to a sealing surface on the engine block such that the oil cooler and the water pump assembly are fluidly sealed to the engine block.