Air Induction

On turbo models, air is drawn through the air cleaner and forced through the throttle body by the turbocharger. Wastegate is controlled by the SMEC and can increase turbo boost to higher levels for brief periods of time. The amount of air entering the engine is controlled by a cable operated throttle valve in the throttle body.

On all models, the throttle body houses the Throttle Position Sensor (TPS) and Automatic Idle Speed (AIS) motor. The TPS is an electrical resistor which is connected to the throttle valve. The TPS transmits a signal to the SMEC in relation to throttle valve angle. From this signal, the SMEC calculates fuel injector "on" time to provide adequate air/fuel mixture.

The AIS motor controls the flow of air through the throttle body during engine idle. The motor opens and closes an air by-pass on the back of the throttle body to increase or decrease idle speed as engine load varies. The SMEC monitors the AIS motor and issues a change command to the injectors to increase or decrease the amount of fuel injected.