Air Injection Control Valve: Description and Operation

AIR ECT Valve Circuit:

EAC Valve:

Description
The ECT valve directs the air from the air pump to the engine exhaust manifold ports or to the air cleaner.


Operation
When the engine is started with a coolant temperature above 15° C (45° F), the ECM energizes the solenoid on the AIR Control Valve which directs air to the exhaust manifold.

1. At higher speeds, air can be redirected to the air cleaner by the pressure relief valve even though the solenoid is energized.

2. Air can also be directed to the air cleaner if the following conditions exist:

- Low manifold pressure (overrun).
- Quick vacuum rise (rapid deceleration).
- Rich engine condition.

3. The solenoid can be de-energized and air is directed to the air cleaner, under the following conditions:

- If the engine coolant temperature is too low.
- If the throttle is opened to power enrichment for more than a short time.
- If the system is in "Closed Loop" mode.
- If the MIL (Service Engine Soon) lamp is ON.

4. Some applications will switch air to the ports for a short time when entering power enrichment.

- Some applications have a "Closed Loop" idle with air directed to the air cleaner.