Air Injection: Description and Operation

Air Injection System:

Air Injection Control System:

PURPOSE AND OPERATION
To reduce excess carbon monoxide and hydrocarbon emissions during engine warm-up, this system injects air into the exhaust ports through air rails on each cylinder bank. Air rail check valves prevent backflow of exhaust gas into the air pump from backfire, belt failure or exhaust system blockage.

Whenever the engine is started, a timer allows the vacuum solenoid to be energized for 45 seconds, supplying manifold vacuum to the diverter valve (air switching valve). The valve then directs pump air to exhaust ports. This period of time permits the catalytic converters to warm up to efficient operating temperatures.

Except as regulated by the vacuum solenoid timer, the diverter valve only directs air to exhaust ports during the engine warm-up period. When engine coolant reaches 100°F (38°C), a thermal vacuum valve switches the diverter valve so that pump air flow is redirected from exhaust ports and dumped into the air cleaner.

A vacuum delay valve in line between thermal valve and diverter valve prevents vacuum loss to the diverter valve during wide open throttle operation.