tcs throttle valve 12 the tcs motor 14 the tcs motor control unit 15 the fuse 16 and the relay 17 form a traction control system 18 by passing the primary throttle valve 11 an auxiliary air passage 5 with an auxiliary air control valve 6 is provided for controlling auxiliary air flow rate introduced through the auxiliary air passage the air induction system 2 also has an intake manifold connecting the throttle chamber 3 to an intake port not clearly shown one or more fuel injection valves 4 is inserted into the intake manifold for injecting a controlled amount of fuel at a controlled timing for forming an air fuel mixture to be introduced into an engine combustion chamber in the internal combustion engine 1 the internal combustion engine 1 is also associated with a spark ignition system 20 with spark ignition plugs 19 which are inserted into respective engine cylinders for initiating combustion of the air fuel mixture at controlled timings determined in relation to engine revolution cycles the spark ignition system 20 may include an ignition coil a distributor unit and so forth for distributing an ignition power to respective spark ignition plugs 19 the internal combustion engine 1 also has an exhaust system for discharging an exhaust gas therethrough an oxygen sensor 23 is inserted into an exhaust pipe 24 for monitoring oxygen concentration which is representative of an air fuel ratio of the air fuel mixture undergoing combustion in the.