PURPOSE: To simply suppress knocking and prevent an abnormal rise of the exhaust temperature by changing the predetermined maximum delay angle quantity to the larger maximum delay angle quantity and also cutting the fuel feed under a specific condition.
CONSTITUTION: The ignition timing of a gasoline engine is controlled with the predetermined maximum delay angle quantity as the upper limit (P1) using the fuel with a predetermined octane value. When the octane value is low (P0), the predetermined maximum delay angle quantity is changed to the larger maximum delay angle quantity (P2). When the rotation speed (P3) and load (P4) of the engine become predetermined values or higher, the fuel feed to the gasoline engine is cut (P5). Accordingly, knocking can be suppressed by using the fuel with different octane values, and an ill effect due to the exhaust temperature rise can be preveted.
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