To uniformize engine output without correcting and controlling the ignition timing when an exhaust emission control device functions, by controlling a cylinder to the rich air-fuel ratio and the other cylinder to the lean air-fuel ratio when an exhaust emission controlling catalyst is not poisoned, and increasing or decreasing the amount of air to be introduced to respective cylinders according to air-fuel ratios of respective cylinders.
When an individual cylinder air-fuel ratio control means 30 is operated, the amount of air to be introduced to respective cylinders is increased or decreased by an individual cylinder air amount control means 50 according to the air-fuel ratio of a cylinder and the other cylinder. When the amount of fuel to be injected to respective cylinders is increased or decreased according to the increased or decreased air amount simultaneously with the increase or the decrease, output of cylinders 1A, 1D controlled to the rich air-fuel ratio is decreased, and output of cylinders 1B, 1C controlled to the lean air-fuel ratio is increased. As a result, torque (output) of respective cylinders can be made constant without changing the air-fuel ratios of respective cylinders. Therefore, the difference of output between respective cylinders is eliminated, and operating feeling can be improved.
IRISAWA YASUYUKI
KADOOKA TAKU
