Air Injection: Description and Operation

PURPOSE
Only manual transaxle vehicles have the pulsed secondary air injection system. The system injects fresh air upstream of the catalytic convertor. It operates for a short period after cold engine start-up until the engine coolant temperature reaches approximately 52° C (125°F).

The secondary air injection system contains:
- Pulsed secondary air injection valve
- Pulsed secondary air injection solenoid
- Connecting hoses and tubes

OPERATION
The Powertrain Control Module (PCM) controls the ground path for the pulsed secondary air injection solenoid. When the PCM grounds the solenoid, fresh air from the air cleaner flows through the pulsed secondary air injection valve to the catalytic converter.
The valve prevents exhaust gases from flowing into to the fresh air stream at the air cleaner when the solenoid is grounded. If the valve malfunctions, a popping noise can be heard during cold start throttle stabs.