Method of reforming a knock learning value

摘要

PURPOSE: A method for reforming knock learning value is provided to maintain an optimum engine performance even in case of using a low level fuel by creating and applying map data for ignition timing for low level fuel. CONSTITUTION: A method for reforming knock learning value comprises a step(S11 to S13) of reading the first knock learning value, ignition timing map data as the first base map data, and ignition timing map data as the first retard map data, and calculating the first target ignition timing; a step(S14 to S17) of decreasing the first knock learning value in case of occurrence of knock, and increasing the first knock learning value in case of non-occurrence of knock; a step(S18,S19) of determining, as the second base map data, the ignition timing obtained when the first target ignition timing is the same as the value obtained by multiplying 1.1 to the first retard map data, when the first knock learning value is lower than 0.5; a step(S20) of determining, as the low octane value map data, the map data obtained by subtracting a predetermined value from the first retard map data, and substituting the first knock learning value with the second knock learning value; a step(S21) of calculating the second target ignition timing on the basis of the second knock learning value, the second base map data and the low octane value map data; and a step(S22 to S25) of decreasing the second knock learning value when the second knock is higher than the reference value, and increasing the second knock learning value when the second knock is lower than the reference value.