Abstract: A method and apparatus for controlling the operation of a “lean-burn” internal combustion engine in cooperation with an emissions control device capable of alternatively storing and releasing an exhaust gas constituent when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, determines an ability of the device to store the exhaust gas constituent by initiating a lean engine operating condition immediately following a first purge event; discontinuing the first lean engine operating condition in favor of a second purge event when the instantaneous efficiency of the device falls below a reference value; and determining the amount of excess fuel necessary to release the thus-stored amount of exhaust gas constituent.

Abstract: An EGR system monitor combines an inferred manifold absolute pressure based on measured mass air flow with a measured manifold absolute pressure to obtain a more complete system response during a test procedure involving the opening and closing of the EGR valve.

Abstract: An engine controller for an automotive engine having an inlet system and an exhaust system includes an EGR valve for permitting exhaust gas to flow from the exhaust system to the inlet system, and an engine controller for operating the EGR valve by closing it from its normal open position. The difference in exhaust gas pressures in an EGR line downstream of the EGR valve measured during the EGR valve normal open and closed positions is compared with first and second threshold values and the actual pressure with the EGR valve open is compared with a third threshold value to determine whether the EGR system is blocked.

Abstract: An engine control for an automotive engine having an inlet system and an exhaust system includes an EGR valve for permitting exhaust gas to flow from the exhaust system to the inlet system, and an engine controller for operating the EGR valve by opening the valve during successive test periods separated by non-uniform intervals, while measuring engine speed response to the opening of the EGR valve so as to diagnose an improperly operating EGR valve.

Abstract: A method and apparatus for monitoring an EGR system during normal vehicle operations is disclosed. An EGR valve located in an EGR passage controls the flow of exhaust gas to an intake manifold, and a sensor disposed in the air intake manifold downstream of air and EGR confluence point, monitors temperature of the mixture. A controller calculates a correlation function between a calculated desired EGR flow and the output of the manifold temperature sensor. If the value of correlation function is lower than a reference level, the monitoring system deterioration of EGR flow rate is indicated.

Abstract: A method and apparatus is provided for determining if the valve deactivator on a variable displacement internal combustion engine is functioning properly. The occurrence of an asymmetry in one of the cylinder banks when making fuel mass calculations during the fractional mode (four cylinders) and the presence of substantial symmetry in fuel mass calculations during maximum mode (eight cylinders) of engine operation indicates a possible deterioration of the valve deactivator. Also, if the ratio of the difference between the expected MAP and the actual MAP during fractional cylinder mode and maximum cylinder mode exceed a calibratable value possible valve deactivator deterioration is also indicated. In a preferred embodiment, these two monitoring methods are combined to provide a more robust indicator, so that if both indicate a possible problem, then an indicator lamp is illuminated to signal that service personnel should check whether the valve activators are properly functioning.

Abstract: An inferred manifold absolute pressure based in part on measured manifold mass air flow is compared with a measured manifold absolute pressure from a MAP sensor and if the rolling average of the difference between the two exceeds either a rich or lean limit, an indicator is energized and a code is stored to identify possible MAP sensor deterioration.

Abstract: A method and system for monitoring fuel delivery to an internal combustion engine having a first and second mode of operation and controlling the engine accordingly. An oxygen content of exhaust gas emitted from the engine is sensed and a corresponding oxygen content signal is generated. Air fuel ratio correction data is determined based on the oxygen content signal. If the engine is operating in the first mode, the air fuel ratio correction data is compared to a first set of predetermined air fuel ratio correction thresholds and a first failure signal is generated based on the comparison between the air fuel ratio correction data and the first set of predetermined air fuel ratio correction thresholds.

Abstract: A control system and method for indicating the efficiency of a catalytic converter coupled to a variable displacement engine. A preselected group of cylinders is activated in a first engine operating and all cylinders are activated during a second engine operating mode. A converter test period is provided when a count in output transitions of the upstream sensor reaches a first preselected value while operating in the first mode and count in transitions of the upstream sensor reaches a second preselected value while operating in the second mode. Converter efficiency is generated by computing a ratio of upstream sensor counts to downstream sensor counts during the test period.