Air Injection: Description and Operation

In certain markets the engine management system is equipped with a secondary air injection system. This consists of an air pump and a valve.

Both these components are controlled by their own control modules, which ground relay 324. The coil of this relay is supplied with current from distribution terminal 159. The relay contact is connected to distribution block 75.

To get the catalytic converter working as soon as possible after a cold start, ambient air is pumped into the exhaust manifold where the oxygen in the air starts a chemical combustion process.

When the engine has started, secondary air injection pump 326 starts and boost pressure control valve 325 opens the connection to the exhaust manifold.

The function is time and temperature dependent. The boost pressure control valve closes and the pump stops after a maximum of 80 seconds or when engine temperature reaches 65 °C.

Secondary Air Injection Pump 326
When the engine management system's control module grounds relay 324, the relay contact closes and current is supplied to the pump via maxi fuse 1. The pump then starts.

Secondary Air Injection Control Valve 325
When relay 324 operates, current is also supplied to the valve via fuse 13. The valve then opens.