Patent ID: 8150598

Claim:
An engine controller comprising: air-fuel ratio control means for controlling an air-fuel ratio to be within a predetermined range when an engine is operated at a certain driving condition; and ignition timing correction means for correcting ignition timing to a retard side when the engine is operated at the certain driving condition and the air-fuel ratio is within the predetermined range; wherein, the air-fuel ratio control means, when the engine speed variation is below a predetermined range A, makes correction to decrease a fuel injection amount until the engine speed variation reaches within the predetermined range A, when the engine speed variation is above the predetermined range A, makes correction to increase the fuel injection amount until the engine speed variation reaches within the predetermined range A, and when the engine speed variation is within the predetermined range A, keeps the correction value for the fuel injection amount; after the air-fuel ratio control means keeps the correction amount for the fuel injection amount, the ignition timing correction means, when the engine speed variation is below a predetermined range B, corrects the ignition timing to the retard side until the engine speed variation reaches within the predetermined range B, when the engine speed variation is above the predetermined range B, corrects the ignition timing to an advance side until the engine speed variation reaches within the predetermined range B, and when the engine speed variation is within the predetermined range B, stops revision of the correction of the ignition timing and keeps the correction value; and the predetermined range A is set to be smaller than the predetermined range B.