A control system for an automobile engine having intake and exhaust systems for respectively conducting intake gases to and exhaust gases from the engine comprises a turbocharger including a turbine disposed in the exhaust system and a blower disposed in the intake system and drivingly connected with the turbine, an exhaust purifying device disposed in the exhaust system downstream of the turbine with respect to the direction of flow of the exhaust gases, a choke valve for varying the effective cross-section of a portion of the exhaust system leading to the turbine, a control device for controlling the choke valve in dependence on an operating condition of the engine, and a correcting unit for controlling the choke valve to increase the effective cross-section during a particular engine operating condition associated with a cold start of the exhaust purifying device. The control device causes the choke valve to increase the effective cross-section during a high speed operating condition, but to decrease the effective cross-section during a low speed operating condition of the engine.