Air Injection: Description and Operation

Fig. 51 Air Injection System Diagram:

PURPOSE
The Air Injection System pumps air from the air cleaner into the exhaust ports to promote oxidation of CO and HC. The heat created by the oxidation process also brings the catalytic converter up to operating temperature more quickly.

OPERATION
Air Injection takes place only when coolant temperature is between 17°C (63°F) and 70°C (158°F), engine speed is less than 2500 RPM, the full load contact is open, and the oxygen sensor is in open-loop operation. Under these conditions the electromagnetic clutch of the air pump is switched on by the CIS - E control unit via the injection relay. The injection relay simultaneously powers the change-over valve which supplies 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 heads.