Examination
1. Remove the air filter cover and air filter following the instructions in subsection 6.1.2.
2. Start the engine, gradually increase the speed to 3000 rpm and hold it there. Use your finger to block the vacuum hose opening of the air valve on the base of the air filter housing, then quickly lower the throttle lever to bring the engine back to normal idle speed. When the throttle lever is released and the engine returns to normal idle speed, a vacuum should form in the air valve hose. If not, replace the valve.
Air valve replacement
1. The valve is located on top of the intake manifold on the right side of the throttle body.
2. Remove the valve from the mounting clip, then disconnect the three hoses from the valve, noting their installation position.
3. Installation is carried out in the reverse order of removal. When installing, check that the hoses are connected correctly.