Air Injection System: Operation: Notes

The Air Injection System is designed to send secondary air to the exhaust manifold, utilizing a vacuum created by exhaust pulsations in the exhaust manifold. Exhaust pressure in the exhaust manifold usually pulsates in response to opening and closing of exhaust valves, and periodically it decreases below atmospheric pressure. When this happens, a vacuum is created and a secondary air intake is opened, allowing secondary air to be drawn into the exhaust manifold in direct proportion to the vacuum.