See Figure 1
- Disconnect the air supply hose from the air cleaner and check for vacuum by placing your thumb over the end of the air supply hose.
- With engine coolant temperature between 64-145°deg;F (18-63°deg;C) and the engine idling, the hose should draw vacuum.
- With the engine coolant temperature at 145°deg;F (63°deg;C) or more, the hose should draw vacuum for 70 seconds after start-up. The hose should not draw vacuum after 70 seconds.
- With the engine coolant temperature at 145°deg;F (63°deg;C) or more, and the engine decelerating from 4000 rpm, the hose should draw vacuum.
If the secondary air control valve is not functioning properly, emission may blow back.
- Remove the secondary air control valve.
- Blow in the air cleaner side of the valve to check that air does not flow through the valve.
- Connect a hand vacuum pump to the secondary air control valve nipple and apply 5.9 in. Hg of vacuum.
- Air should flow from the air cleaner side to the exhaust manifold side. Air should not flow from the exhaust side to the air cleaner side.
- Replace the air control valve if it fails any of the above tests.
- Tighten the air control valve to 51-61 ft. lbs. (69-82 Nm).