Abstract: Methods and systems are provided for regulating the temperature of rear axle lubrication oil. In one example, a rear axle coolant system may include a coolant loop with a plurality of valves and sensors, regulating the coolant flow in heat exchange relationship with an exhaust gas heat recovery and storage system to deliver warm coolant to a rear axle heat exchanger to warm the rear axle lubrication oil. The method may regulate the components of the rear axle coolant system through a controller, receiving sensor input from the components of the coolant system.

Abstract: Methods and systems are provided for controlling coolant flow through parallel branches of a coolant circuit including an AC condenser and a charge air cooler. Flow is apportioned through each of an air-conditioning condenser, a charge air cooler (CAC), and a transmission oil cooler (TOC) of the coolant circuit to maintain an estimated transmission oil temperature (TOT) below a threshold. The TOT is estimated from a torque converter slip ratio.

Abstract: Systems and methods for activating and deactivating cylinders of an engine that may activate and deactivate one cylinder independent of other cylinders are presented. In one example, an engine cylinder firing fraction and a remainder value that is based on the engine cylinder firing fraction are a basis for activating and deactivating engine cylinders. The systems and methods also provide for transitioning between different cylinder firing fractions.

Abstract: Methods and systems are provided for controlling coolant flow through parallel branches of a coolant circuit including an AC condenser and a charge air cooler. Flow is apportioned responsive to an AC head pressure and a CAC temperature to reduce parasitic losses and improve fuel economy. The flow is apportioned via adjustments to a coolant pump output and a proportioning valve.

Abstract: Methods and systems are provided for determining coolant system health. In one example, a method may include predicting degradation in the coolant system based on oscillations of an estimated coolant temperature at an outlet of a radiator. The method may further control an engine based on the estimated coolant temperature.

Abstract: Methods and systems are provided for regulating the temperature of rear axle lubrication oil. In one example, a rear axle coolant system may include a coolant loop with a plurality of valves and sensors, regulating the coolant flow in heat exchange relationship with an exhaust gas heat recovery and storage system to deliver warm coolant to a rear axle heat exchanger to warm the rear axle lubrication oil. The method may regulate the components of the rear axle coolant system through a controller, receiving sensor input from the components of the coolant system.

Abstract: Methods and systems are provided for regulating the temperature of rear axle lubrication oil. In one example, a rear axle coolant system may include a coolant loop with a plurality of valves and sensors, regulating the coolant flow in heat exchange relationship with an exhaust gas heat recovery and storage system to deliver warm coolant to a rear axle heat exchanger to warm the rear axle lubrication oil. The method may regulate the components of the rear axle coolant system through a controller, receiving sensor input from the components of the coolant system.

Abstract: Systems and methods for activating and deactivating cylinders of an engine that may activate and deactivate one cylinder independent of other cylinders are presented. In one example, an engine cylinder firing fraction and a remainder value that is based on the engine cylinder firing fraction are a basis for activating and deactivating engine cylinders. The systems and methods also provide for transitioning between different cylinder firing fractions.

Abstract: 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.

Abstract: Systems and methods for activating and deactivating cylinders of an engine that may activate and deactivate one cylinder independent of other cylinders are presented. In one example, an engine cylinder firing fraction and a remainder value that is based on the engine cylinder firing fraction are a basis for activating and deactivating engine cylinders. The systems and methods also provide for transitioning between different cylinder firing fractions.

Abstract: Methods and systems are provided for monitoring torque delivery in a variable displacement engine using air flow metered via a throttle body model. During conditions when air flow estimation can be inaccurate, such as at wide open throttle, an induction ratio applied to the engine is constrained to 1.0, even if the operator torque demand is low. VDE degradation is inferred based on the commanded induction ratio relative to an actual induction ratio estimated based on the torque delivery.

Abstract: 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.

Abstract: 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.

Abstract: Methods and systems are provided for monitoring torque delivery in a variable displacement engine using air flow metered via a throttle body model. During conditions when air flow estimation can be inaccurate, such as at wide open throttle, an induction ratio applied to the engine is constrained to 1.0, even if the operator torque demand is low. VDE degradation is inferred based on the commanded induction ratio relative to an actual induction ratio estimated based on the torque delivery.

Abstract: Systems and methods are provided for increasing the accuracy of air charge estimation for a cylinder that is selectively deactivatable. A controller may deactivate the cylinder in accordance with a firing pattern selected based on torque demand. An air charge estimate of the firing cylinder is then adjusted based on whether the cylinder was fired or skipped on a previous engine cycle when operating according to the selected firing pattern.

Abstract: Systems and methods are provided for increasing the accuracy of air charge estimation for a cylinder that is selectively deactivatable. A controller may deactivate the cylinder in accordance with a firing pattern selected based on torque demand. An air charge estimate of the firing cylinder is then adjusted based on whether the cylinder was fired or skipped on a previous engine cycle when operating according to the selected firing pattern.

Abstract: 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.

Abstract: Systems and methods for activating and deactivating cylinders of an engine that may activate and deactivate one cylinder independent of other cylinders are presented. In one example, an engine cylinder firing fraction and a remainder value that is based on the engine cylinder firing fraction are a basis for activating and deactivating engine cylinders. The systems and methods also provide for transitioning between different cylinder firing fractions.

Abstract: Methods and systems are provided for controlling coolant flow through parallel branches of a coolant circuit including an AC condenser and a charge air cooler. Flow is apportioned responsive to an AC head pressure and a CAC temperature to reduce parasitic losses and improve fuel economy. The flow is apportioned via adjustments to a coolant pump output and a proportioning valve.

Abstract: Methods and systems are provided for controlling coolant flow through parallel branches of a coolant circuit including an AC condenser and a charge air cooler. Flow is apportioned responsive to an AC head pressure and a CAC temperature to reduce parasitic losses and improve fuel economy. The flow is apportioned via adjustments to a coolant pump output and a proportioning valve.