Air Injection: Testing and Inspection

Air Injection takes place for a about 110 seconds after start up and only when the coolant temperature is between 10°C (50°F) and 40°C (105°F), the engine speed is less than 3000 RPM, the full load contact is not closed, and the oxygen sensor is not in closed loop. Under these conditions the electromagnetic clutch of the air pump is switched on by the CIS - E control unit via the engine systems (MAS) control unit. The engine systems (MAS) control unit simultaneously powers the change-over valve which provides vacuum to the air shut-off valve in the pump circuit. Air is then pumped through the check valve and into the exhaust ports of the cylinder head.
The diagnostics of the CIS - E control unit checks the function of the entire air injection system. Under the following conditions the air pump is operated after each start-up for 5 seconds:

a. The engine idling at normal operating temperature.
b. The vehicle not moving.
c. The oxygen sensor system in closed loop.

The CIS - E control unit can determine whether the air injection system is operating properly by the feedback which it receives from the oxygen sensor signal. If a malfunction is recognized, it is stored in the on-board diagnostics of the CIS - E control unit. Refer to COMPUTERIZED ENGINE CONTROLS for tests concerning air injection control.