Abstract: An adaptive closed loop fuel control system generates an index of maturity value which indicates the extent to which parameters which characterize an individual engine have been learned and stored for future use in a non-volatile memory. A timer produces the index of maturity value by measuring the elapsed time during which the fuel control system has successfully operated the engine at or near stoichiometry within a predetermined range of engine speed and load conditions. A backup mechanism counts the number of HEGO sensor state changes as the closed loop controller operates in an adaptive mode, setting the index of maturity to a predetermined value even when the measured adaptation time fails to indicate an adequate amount of adaptive operation.

Abstract: An electronic engine controller operates to control the phase angle of a variable position camshaft. The engine controller receives signals indicative of engine coolant temperature, aircharge temperature, throttle position, engine speed and camshaft position, and generates a camshaft position signal to a variable camshaft control actuator to alter the phase angle of the camshaft with respect to the engine crankshaft. The engine controller contains two tables which contain cam phase angles. The first table contains a plurality of values indexed by engine speed and engine aircharge and the second table contains a plurality of values indexed by engine speed and throttle position. The engine controller generates the camshaft position signal in one of three manners depending on the mode of engine operation. In a first mode of engine operation the camshaft position signal is generated as a function of engine coolant temperature and aircharge temperature.

Abstract: A method of inferring the temperature of a heated exhaust gas oxygen sensor is used in the control of the operation of an electronic engine control for an internal combustion engine.

Abstract: A method and system for estimating and controlling the temperature of an electrically heated catalyst having a heating element disposed in an exhaust passage of an internal combustion engine. Mass air flow into the engine is sensed. A temperature at an inlet of the catalyst is first determined. Next, a steady-state temperature rise of the heating element is determined based on the catalyst inlet temperature. The steady-state temperature rise is converted into an instantaneous temperature rise having a time constant based on the sensed mass air flow. A total catalyst temperature of the catalyst is then determined based on the catalyst inlet temperature and the instantaneous temperature rise. Finally, the heating element of the electrically heated catalyst is controlled based on the total catalyst temperature.

Abstract: A fuel delivery system is disclosed in which fuel pressure at a fuel rail is controlled by controlling electrical power applied to an electric fuel pump. The fuel pressure is controlled to maintain the minimum value required to meet two constraints. The first constraint is the quantity of desired fuel to be delivered by the injectors at wide-open throttle as a function of engine speed. The second constraint is to provide enough pressure to meet fuel requirements as the available fuel injector on-time decreases with increasing engine speed.

Abstract: The present invention is a method for obtaining an inferred soak time suitable for inferring exhaust system and other temperatures with sufficient accuracy to permit control of at least one feature of an internal combustion engine to be based thereon. In this way, soak time strategy can be inexpensively incorporated into an engine control system not based on soak time or soak timer hardware can be replaced in control systems with soak time strategy. The temperature of the engine and of the charging air supplied to the engine are measured at the time the engine is turned off and when the engine is restarted. The measured temperature of the engine and of the charging air at the time the engine is turned off is stored in a computer memory. The inferred soak time is obtained using the measured temperature of the engine and of the charging air stored at the time the engine is turned off and measured at the time the engine is restarted.

Abstract: An electronic ignition timing system which cooperates with an adaptive closed loop fuel control system to provide more rapid heating of an exhaust catalyst by retarding the ignition tinning during colds starts only after an index of maturity value has been generated to indicate that fuel control parameters which characterize an individual engine have been adaptively learned and are available to operate the engine with a lean mixture during cold idling conditions. The index of maturity value alters the mode of operation of the fuel control mechanism to provide robust rich operation prior to adaptation and a more aggressive lean mode operation after the adaptive parameters have been developed which permit optimized operation, and alters the ignition timing to retard the spark to more rapidly heat the exhaust catalyst.

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 reducing hydrocarbon emissions exhausted from an internal combustion engine includes timing the opening and closing of valved intake and exhaust ports to overlap for a predetermined time period, and introducing at least one of a pressure decrease at the intake passage during said overlap and a pressure increase in said exhaust passage during said overlap to reduce late hydrocarbon emissions during the overlap. Preferably, a pressure transducer such as an acoustic transducer may be driven to provide an increased pressure pulse at the exhaust port during the overlap period. Alternatively, a preferred implementation of reduced pressure at the intake port includes the operation of a throttle bypass valve that reduces fluid flow to the intake port.

Abstract: An engine controller (12) controls an ignition system (88) and bypass throttle valve (96). An ignition timing signal is set to an initial value as a function of engine (10) operating parameters. The timing signal is retarded during cold operation to rapidly warm a catalyst converter (20) coupled to the engine exhaust (48). When the vacuum in the intake manifold (44) falls below a threshold level, the ignition timing signal is advanced beyond the initial value. The ignition timing signal is retarded back towards its initial value when the manifold vacuum exceeds the threshold value. Concurrently, the initial timing signal is controlled to achieve desired engine idle speed.

Abstract: A method of controlling the operation of heaters for an exhaust gas oxygen sensor as function exhaust gas temperature as compared to a first exhaust gas temperature to turn on the heaters and a second exhaust gas oxygen sensor temperature to turn off the heaters.

Abstract: An engine controller (12) controls engine idle speed via control of a bypass throttle valve (96) and an ignition timing system (88). The ignition system (88) also provides a retard in ignition timing during cold operation to rapidly warm a catalytic converter (20) coupled to the engine exhaust (48). When first entering the idle speed control mode, an initial throttle position corresponding to an initial desired inducted mass air flow is first provided as a function of predetermined conditions such as air conditioner status. This initial value (238, and 402-412) is corrected to prevent any decrease in idle speed which would otherwise occur as a result of the afore-mentioned retard in ignition timing.

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: An electronic engine controller limits the maximum temperature of a midbed point within a catalytic converter by determining an instantaneous temperature of the midbed point as a function of a temperature of exhaust gas at an exhaust flange, of a temperature variation of exhaust gas from the exhaust flange and exhaust gas inlet to the catalytic converter, of exhaust gas at an exhaust gas inlet to the catalytic converter, and as a function of a predetermined value indicative of a temperature rise of exhaust gas in the catalytic converter. The temperature is compared to a maximum midbed temperature range and a first air/fuel modulation variable is altered by a predetermined amount if the temperature of the midbed point is within the maximum midbed temperature range and the first air/fuel modulation variable is set to a predetermined value if the midbed temperature is below the maximum midbed temperature range.

Abstract: Method and apparatus for controlling ignition timing during alternating rich and lean fuel-air composition excursions for efficiency and for controlling torque fluctuations associated with the excursions. The method, for use in a vehicle having an internal combustion engine including an electronic fuel and spark control module, includes reducing spark advance instantaneously during a rich fuel-air excursion, and increasing spark advance during a lean fuel-air excursion. The amount of spark advance adjustment is preferably determined utilizing nonlinear functions which relate spark, torque ratios, and air-fuel ratios.

Abstract: A diagnostic method for an internal combustion engine determines airflow using three independent airflow determinations. The three airflow determinations are compared to each other and an error is established if one airflow determination differs significantly from at least one other airflow determination.

Abstract: A mass airflow based control system for an internal combustion engine is provided which is capable of inferring cylinder air charge during non-steady state periods of operation of the engine. The control system infers cylinder air charge from values of rotational engine speed, air mass flow inducted into the engine, inlet air temperature, engine coolant temperature, and barometric pressure. The control system employs the inferred cylinder air charge value for air/fuel ratio control.

Abstract: A method of operating an internal combustion engine wherein a predicted engine exhaust temperature is used as an input to a microprocessor controlling the engine. Exhaust temperature can be controlled by adjusting engine operation. Exhaust gas recirculation mass flow can be more accurately determined using the predicted engine exhaust temperature.