EXHAUST GAS PURIFIER OF MULTICYLINDER ENGINE

PURPOSE:To effectively purify exhaust gas without lowering the output by providing a device controlling the condition of engine combusion so that the temperature of exhaust gas from the first cylinder group is higher than that from the second cylinder group. CONSTITUTION:When the temperature of a catalytic converter 12 detected by means of a sensor 18 is higher than a set temperature, a control circuit 19 does not send out a signal and a three-way valve 20 is in a condition as shown by a drawing. Accordingly, the first and the second cylinder groups 2, 3 are given lead angles in comparison with the normal ignition timing. On the other hand, when the temperature of the catalyst is lower than the set temperature, the control circuit 19 sends out a signal, and the three-way valve 20 operates to put a negative pressure introduction pipe 22 in communication with the atmosphete. Thus, a vacuum lead angle mechanism 16 does not operate, and the first cylinder group 2 is given a lag angle in comparison with the normal ingition timing. Accordingly, afterburning occurs and burning time is prolonged, then the temperature of the exhaust gas is raised.