Abstract: Integrated control of internal combustion engine fueling including control of fuel injectors and control of purge valve position to vary the rate at which fuel vapor trapped in a canister is purged to an engine intake manifold, determines the mass of purge vapor reaching the intake manifold, estimates the mass of purge vapor reaching each engine cylinder, and adjusts the engine cylinder fuel injection mass in response thereto to provide an accurate overall cylinder fueling insensitive to the purge rate, allowing the purge control operations to be aggressively driven while ambitious cylinder air/fuel ratio standards are maintained. Feedforward purge control proactively adjusts purge control commands in response to desired cylinder purge mass and to purge vapor flow dynamics and feedback purge control trims the purge control commands in response to a difference between the desired cylinder purge mass and estimated cylinder purge mass.

Abstract: Misfire is detected in an internal combustion engine during its starting mode by analyzing the engine speed profile. Average speed is determined for 60.degree. increments of crankshaft rotation. If an increment midway between top dead center positions has a higher speed than the previous increment and a higher speed than cranking speed, combustion occurred, otherwise a misfire occurred. When misfires are detected for a particular cylinder the calculated fuel allotment for that cylinder is reduced in accordance with the number of consecutive misfires for that cylinder.

Abstract: A microprocessor based electronic spark control for an internal combustion engine is programmed to determine spark time using a prediction of engine speed during the spark period in which the next spark should occur and to make the calculations immediately prior to that period. The prediction is based upon the most recent speed information including a reference period value just prior to the next spark period. Reference pulses produced from a crankshaft driven transducer determine the measured reference periods and preferably comprise a plurality of pulses per spark event. One reference period is chosen as a base period and a weighted difference of recent periods is used to adjust the base to predict the spark period. The spark period or the corresponding engine speed is used in calculating the spark angle and the conversion to spark time. A hardware interrupt to the microprocessor causes the calculations to be made when the reference pulse nearest the next spark occurs.