Misfire state discrimination system of internal combustion engine

1. Field of the Invention A misfire state discrimination system of an internal combustion engine, which determines the occurrence of misfire under engine operating conditions that make misfire determination possible and counts the number of misfires to compare with a reference value. The misfire state of the engine is discriminated based on the result of comparison. In the system, when the engine operation moves from the conditions that makes the misfire determination possible, the count is saved and is counted up from the count when the engine operation returns to the condition. The saved count is also retained when the engine is stopped. Similarly, the number of combustion during which the determination of misfire occurrence is made is counted and the count is saved. This arrangement enables a rapid and accurate discrimination of the misfire state of the engine.