Air Induction

Air is drawn into combustion chamber through air cleaner and intake manifold. Amount of air entering engine is controlled by position of throttle body valve. Throttle body houses throttle position sensor (TPS) and idle speed solenoid (ISS) motor. TPS is an electrical resistor which is connected to throttle valve. TPS transmits a signal to ECU in relation to throttle valve angle. This signal is used in calculations to determine injector pulse width to provide adequate air/fuel mixture.

ECU controls idle speed by providing appropriate voltage outputs to move ISS motor pin inward or outward to maintain a predetermined idle speed. ECU continuously monitors TPS and ISS motor and issues change commands to injectors to increase or decrease amount of fuel injected.