Air Induction
On the 1.6L engine, air enters the engine through the throttle assembly at a rate controlled by the throttle valve, which is connected to conventional throttle linkage.
An air by-pass channel is incorporated into assembly to satisfy both cold and warm idle airflow requirements when throttle valve is in a fully closed position. Airflow through by-pass channel is controlled by air by-pass valve which is mounted directly to throttle body. Air by-pass valve function is in turn controlled by signals from the ECA.
On the 2.3L Turbo engine, air is drawn through the air cleaner and passes through the throttle assembly. Incoming air enters compressor side of turbo unit and is delivered under pressure to intake manifold. Fuel is introduced into the pressurized air as the air enters the combustion chamber. See Fig 2 .
Exhaust gases leave combustion chamber and drive turbine wheel of turbo unit. Turbine speed is controlled by an actuator mounted on turbo unit. The actuator senses intake manifold pressure and controls operation of the wastegate assembly. The wastegate controls amount of exhaust gas entering turbine by opening and closing a by-pass passage, thereby controlling turbine speed and preventing "overboost".