Abstract: A fuel control system for an engine utilizing direct fuel injection including a smoke sensor for measuring the level of smoke in the engine exhaust. A control module, in response to the output signal from the smoke sensor, regulates the timing and delivery of fuel to the engine, the delivery of air to the engine, the amount of exhaust gases that are recirculated to the engine, the turbo boost pressure and performs on-board diagnostics.

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 system is provided for controlling the ratio of fuel to air in an internal combustion engine to protect the catalyst substrate of a catalytic convertor from thermal damage. The system comprises detecting a misfire rate and adjusting the amount of fuel within the system accordingly. More particularly, the detected misfire rate is compared to at least one predetermined misfire rate within the engine control unit. If the detected misfire rate is not equal to the predetermined rate, the ratio of fuel to air is changed a calibrated amount. Accordingly, when the misfire rate exceeds a predetermined rate, additional fuel is added to the system. By increasing the ratio of fuel to air, the oxidation reaction is reduced and the exothermic activity within the catalytic converter is lowered.

Abstract: A method of determining start of closed-loop fuel control for an internal combustion engine including the steps of determining a base fuel pulsewidth threshold, ascertaining whether a current accumulated base fuel pulsewidth is greater than or equal to the base fuel pulsewidth threshold, updating the current accumulated base fuel pulsewidth with a value of a previous accumulated base fuel pulsewidth plus the current base fuel pulsewidth if the current accumulated base fuel pulsewidth is not greater than or equal to the base fuel pulsewidth threshold, and beginning a closed loop fuel control of a plurality of fuel transferring components if the current accumulated base fuel pulsewidth is greater than or equal to the base fuel pulsewidth threshold.