Abstract: The analog input of a sensor is connected to a 10-bit analog-to-digital converter. The converted is powered using a 5V supply. The A/D is interfaced with a microprocessor; however, only the least significant eight bits of the A/D output are connected to the microprocessor input. The microprocessor is used to adjust the fuel-air mixture used in engine combustion based on the output of the sensor. The use of the 10-bit A/D interfaced with only eight bits allows increased precision and increased computational speed. The increased precision allows more accurate adjustment of the fuel-air mixture to enable the engine to run closer to its stoichiometric point.

Abstract: A fuel control system is provided including a fuel tank, a purge vapor canister, a vapor line, and a fuel injector connected to an internal combustion engine. A purge vapor canister vent valve seals the purge vapor canister from the atmosphere such that the fuel tank, purge vapor canister, and fuel injector form a closed system. Upon initial starting of the engine, the purge vapor pressure is such that the purge vapor is drawn to the fuel injector from the dome portion of the fuel tank after passing through the purge vapor canister. Simultaneously therewith, the amount of liquid fuel is reducing or increasing by an amount of equally increasing or decreasing, respectively, vapor fuel so that a necessary mass flow rate is achieved to support combustion. As the amount of fuel vapors decreases to a negligible amount, combustion is supported by the atomization of liquid fuel.

Abstract: A methodology of computing a combustion stability value and using the combustion stability value to control engine operation is provided. The combustion stability value is determined by monitoring engine operation. The combustion stability value is compared to an expected combustion stability value. Where the combustion stability value is greater than the expected combustion stability value, combustion of the internal combustion engine is controlled as a function of the combustion stability value. Where the combustion stability value is not greater than the expected combustion stability value, combustion of the internal combustion engine is controlled as a function of an O2 sensor value. In either case, engine control is accomplished by modifying a target fuel injection value.

Abstract: A method is provided for controlling the delivery of fuel to an engine of an automotive vehicle equipped with a dynamic crankshaft fuel control system and an oxygen sensor feedback based fuel control system. The method includes determining an averaged combustion metric from the dynamic crankshaft fuel control system. The combustion metric is compared to an allowable engine roughness value and a dynamic crankshaft fuel control fuel multiplier is adjusted based on the comparison via a proportional-integral-derivative control calculation. Thereafter, the integral term of the dynamic crankshaft fuel control system's proportional-integral-derivative control calculation is stored.

Abstract: A proportional/integral/derivative control system is provided for controlling the operating parameters of a feedback system according to the difference between a measured value from a component of the system and a target set point. The control system employs a linearization curve having a plateau portion near the target set point. As the measured value approaches the target set point, smaller corrective measures are employed to minimize overshooting and fluctuations. Also, a range is established about the set point wherein no corrective measures are performed.

Abstract: A method of adapting a linear EGR system is provided to adjust flow rates based on engine roughness. Initially, the level of engine combustion roughness is measured and quantified by a known dynamic crankshaft fuel control methodology. In response, the method adjusts the EGR valve desired position higher or lower based on the measured combustion roughness. For example, if the engine is running "smooth", then more EGR is used. If the engine is running "rough", less EGR is used. As the engine approaches a roughness target, the EGR is stabilized.

Abstract: A method is provided for controlling spark advance based on a fuel modifier. Initially, engine fueling is reduced according to a known dynamic crankshaft fuel control (DCFC) methodology. As a result, the engine tends to run rougher. In response, spark advance is varied based on the overall fuel multiplier reduction from the DCFC methodology. For instance, a look-up table, or mathematical function based on the DCFC multiplier can be utilized as the basis for the spark advance.

Abstract: A method is provided for enriching a fuel to air ratio in an engine during acceleration based on a known fuel multiplier. Initially, the method retrieves the fuel multiplier from a dynamic crankshaft fuel control (DCFC) system. This system uses the fuel multiplier to reduce the amount of fuel delivered to the engine. When acceleration is desired, the method increases the overall acceleration enrichment values as a function of the DCFC fuel multiplier. Thus, when the vehicle is launched via a throttle tip-in while the DCFC system is active, the acceleration enrichment values are increased thereby improving drivability by having combustion taking place in a richer environment.

Abstract: A methodology of computing a learned combustion stability value and applying the learned combustion stability value to control engine operation is provided. Engine speed is sensed for each expected firing of individual cylinders of the engine. The difference in engine speed for a selected cylinder firing and a cylinder firing occurring two cylinder firings earlier is determined to provide an expected acceleration value. The difference between successive expected acceleration values is computed. A learned combustion related value is determined as a function of the difference in the successive learned acceleration values and is an indication of engine roughness. The operation of the engine is controlled as a function of the learned combustion related value. The learned combustion stability value is advantageously employed so as to modify the fuel injection to an internal combustion engine, especially following a cold engine start so as to reduce hydrocarbon emissions.

Abstract: A method for advanced crank spark with blend spark retard for an internal combustion engine includes the steps of selecting whether a spark in an engine cylinder will be fired on a predetermined first or second crank edge during an engine start mode, firing the spark on the second crank edge during the engine start mode if the second crank edge is selected, firing the spark on the first crank edge if the first crank edge is selected, determining whether the internal combustion engine is in the engine start mode based on engine speed, continuing to select whether to fire the spark on the predetermined first crank edge or the predetermined second crank edge if the internal combustion engine is in the engine start mode based on engine speed less than the predetermined speed, and retarding the spark from a first spark level to a hold start level at a predetermined rate, holding the spark at the hold spark level for a hold period, and advancing the spark to the first spark level at the predetermined rate, if the i

Abstract: A method for pulse width modulating a resistance element of an oxygen sensor. The method quickly heats the resistance element of the oxygen sensor soon after start of the engine with a relatively high duty cycle yielding wide pulse widths. During a mid oxygen sensor temperature range, the method decreasing the duty cycle and thereby the pulse width modulation. And, upon the oxygen sensor reaching peak operating temperature range, the method decreases the pulse width modulated voltage signal supplied to the oxygen sensor to relatively short duty cycled pulses.

Abstract: A circuit and method are provided for heating a dual heater oxygen sensor. One resistance element is of relatively low resistance such that the oxygen sensor is heated quickly and the other element is of relatively high resistance such that the oxygen sensor is heated and maintained at an optimal operating temperature. The circuit and associated method turn on a low resistance start heater that is in communication with the oxygen sensor given start-up conditions. Once the oxygen sensor has reached an operating temperature range a high resistance operating temperature heater is turned on and the start heater is turned off.