Air Injection: Description and Operation

Air Injection System:

PURPOSE
The engine control module drives an electric air pump to send air into the exhaust system and remove CO and HC from the engine exhaust gases by oxidation. The oxidation process produces heat, which brings the oxygen sensors to operating temperature faster as well.

OPERATION
When the engine is cold-started, the engine control module activates the electric air pump relay to drive the air pump. And because the vacuum switching valve is also turned on at this time, the intake manifold pressure opens the air switching valve to start secondary air injection.
Within a few minutes of secondary air injection starting, the engine control module turns off the air pump relay and vacuum switching valve when the engine condition reaches a predetermined level, thus stopping secondary air injection.


*** UPDATED BY TSB #EG94001 DATED MAY 20, 1994 ***

Discontinued Mid 1994 production year. Models with production vin JT8UF11E4R0196973 or later, or have a production date later than 01/94 have no secondary air injection system. Always consult the ECS label to verify equipment required on the vehicle.