Air Injection: Description and Operation

Fig. 39 Secondary Air Supply System (Federal):

FEDERAL VEHICLES

The secondary air system for Federal vehicles consists of a reed valve, combined secondary air control/reed valve, and a secondary air control solenoid valve. Secondary air is used to improve operation of the catalytic converters and is supplied based on coolant temperature, engine speed, time, and idle throttle position.

SECONDARY AIR CONTROL SOLENOID VALVE

The secondary air control solenoid valve is controlled by the ECU and provides vacuum signal to the secondary air control valve during warm-up, deceleration, and hot starts.

SECONDARY AIR CONTROL VALVE

The secondary air control valve is vacuum operated and includes an internal reed valve. It is used to supply additional secondary air to the front catalytic converter.

REED VALVE

The reed valve provides a continuous stream of secondary air to the rear catalytic converter. Pulsations in exhaust system pressure result in short periods of negative pressure which open the reed valve to admit secondary air.

Fig. 40 Secondary Air Supply System (California):

CALIFORNIA VEHICLES

The secondary air system for California vehicles consists of a combined secondary air control/reed valve, and a secondary air control solenoid valve. Secondary air is used to improve operation of the catalytic converters and is supplied based on coolant temperature, engine speed, time, and idle throttle position.

SECONDARY AIR CONTROL SOLENOID VALVE

The secondary air control valve is vacuum operated and includes an internal reed valve. It is used to supply vacuum signal to the secondary air control valve.

SECONDARY AIR CONTROL VALVE

The secondary air control valve is vacuum operated and includes an internal reed valve. It is used to supply additional secondary air to the front catalytic converter.