Abstract: A number of embodiments of engine spark control systems wherein the engine speed is reduced in response to the sensing of an abnormal or an external condition and wherein the spark timing is altered when the spark is interrupted to preclude the likelihood of backfiring in the exhaust system or firing back in the induction system. In some embodiments, the sensed condition is an abnormal running condition and in other embodiments the sensed condition is shifting of the transmission. The backfiring and firing back is precluded primarily by advancing the spark from the idle spark advance.