Abstract: A method for operating an engine during a fuel cut-off mode is disclosed. The method may adjust exhaust valve opening timing and exhaust valve lift of one or more cylinders to heat air flowing through the one or more cylinders so that a temperature of an after treatment device may be maintained or increased.

Abstract: Methods and systems are provided for controlling a vehicle system including an engine that is selectively deactivated during engine idle-stop conditions and selectively reactivated during engine restart conditions. One example method comprises, during an engine restart from an idle stop, performing a first combustion event in a cylinder with a piston at an engine crankshaft position that is after a crankshaft position at which said cylinder's exhaust valve opens, and before a crankshaft position at which the cylinder's intake valve closes, during a cycle of said cylinder. In this way, inaccuracies in cylinder aircharge estimation may be reduced, thereby also reducing air-fuel ratio errors and improving the quality and repeatability of engine restarts.

Abstract: Methods and systems are provided for controlling a vehicle system including an engine that is selectively deactivated during engine idle-stop conditions and selectively reactivated during engine restart conditions. One example method comprises, during an engine restart from an idle stop, performing a first combustion event in a cylinder with a piston at an engine crankshaft position that is after a crankshaft position at which said cylinder's exhaust valve opens, and before a crankshaft position at which the cylinder's intake valve closes, during a cycle of said cylinder. In this way, inaccuracies in cylinder aircharge estimation may be reduced, thereby also reducing air-fuel ratio errors and improving the quality and repeatability of engine restarts.

Abstract: An electronic engine controller (EEC) controls the delivery of fuel to an internal combustion engine via one or more fuel injectors by executing a background routine to measure a plurality of system conditions including airflow and engine temperature. A response value is generated as a function of an aircharge value, the temperature value and a valve effect value. The EEC detects an interrupt which occurs prior to combustion of an air/fuel mixture within each combustion chamber of said engine, and in response to the interrupt execution of the background routine is halted and a foreground routine is executed in which the airflow is measured, an updated aircharge value is generated and the response value is updated as a function of the difference in aircharge values and a predetermined response alteration value. The aircharge value is replaced with the updated aircharge value.

Abstract: An internal combustion engine includes an exhaust gas recirculation (EGR) mechanism for transporting a controlled amount of exhaust gas generated by the engine from the exhaust manifold to an intake manifold of the engine. An electronic engine controller (EEC) controls the EGR rate by determining a base EGR rate as a function of a plurality of engine operating parameters and a blending value which increases the base EGR rate over a predetermined period of time. A maximum EGR rate value is then determined as a function of a value indicative of the ratio of current air charge drawn into an intake manifold of the engine to the peak aircharge available to the engine at wide-open throttle and at the current rotational speed of the engine and the ambient barometric. The base EGR rate is then compared against the maximum EGR rate value and the EGR rate is determined as a function of the lesser of the two values.

Abstract: A method, for use with a vehicle including a multi-cylinder internal combustion engine having exhaust valves, for controlling the temperature of the exhaust valves during fuel cutoff modes of engine operation utilizing a bit pattern representation of the engine cylinders. The method includes cutting off the fuel delivered to the cylinders in an indexed cylinder firing pattern to vary which cylinders receive fuel, so as to maintain acceptable exhaust valve temperature levels. The method may also include operating the engine with a lean air/fuel ratio, so as to maintain acceptable catalytic converter temperature levels.

Abstract: A method for reducing the engine torque being produced by an internal combustion engine to a desired engine torque through coordinated control of spark retard, cylinder cut-out and air/fuel scheduling. The method is for use with a vehicle including a multi-cylinder internal combustion engine capable of generating torque, each cylinder having an associated fuel injector for providing fuel to the cylinder and an associated spark timing control for providing a spark for combustion of the fuel with fresh air during engine operation. The method includes identifying the desired engine torque to which the engine torque being produced is to be reduced, and determining a first torque reduction to be achieved by defueling at least one of the engine cylinders.

Abstract: A method and system is provided for reducing engine spark knock during rapid transient operating conditions. The method includes the step of determining, at periodic intervals, an estimate of airflow into a combustion chamber. The method also includes the step of determining, at periodic intervals, whether rapid transient operating conditions exist. If such conditions exist, an estimated spark advance is determined based on the estimated airflow. Finally, a spark is fired in the combustion chamber based on the estimated spark advance parameter.

Abstract: A method of inferring and predicting engine torque uses a function of a speed/load table, air/fuel ratio and spark advance. The effects of the magnitudes of engine spark retard, rich or lean air/fuel ratios and exhaust gas recirculation are accounted for using a series of multipliers. Friction torque is accounted for through a speed/air charge table look-up.