Air Injection: Description and Operation

Air Injection System:

An air injection pump with electric clutch and vacuum operated air cut-off valve are controlled by EFI ECM. Air injection is enabled after all engine starts. ECM uses strategy comprised of a number of injector pulses versus engine coolant temperatures below 115°F (47°C). Air shut-off valve is operated by vacuum applied by solenoid vacuum valve when signaled from ECM.


A check valve (non-return valve), located in the air delivery line, prevents pump damage from exhaust gas back flow. Air pump clutch and solenoid valve are operated simultaneously through ECM control of the air injection relay. A vacuum delay valve in the vacuum source line prevents switching valve vacuum loss during wide open throttle operation.

By injecting air into the exhaust manifolds, this system reduces excess carbon monoxide and hydrocarbon emissions during engine warm-up.