Air Injection: Description and Operation

In certain markets, the engine management system is equipped with a system for secondary air injection. This consists of an air pump and a valve. Both these components are controlled by their own control modules. These ground relay 324, the coil of which is supplied 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.

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

Secondary Air Injection Pump 326
When the Trionic or Motronic control module grounds relay 324, current is supplied to the pump via the relay contact and fuse 1 (maxi). The pump then starts.

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