Air Suction System Toyota 4Runner I

DESCRIPTION

The air suction system uses exhaust gas pulses to draw air into the exhaust manifold which helps to complete oxidation of emissions. This system includes reed valve, and hoses.

Federal vehicles also use a vacuum control valve (VCV), vacuum transmitting valve (VTV), air switching valve (ASV), and a resonator.

California vehicles use an electronic air control valve (EACV), thermo switch, vacuum switch and a resonator.

OPERATION

Air is drawn through the filter and air suction (AS) valve into exhaust manifold.

Air Switching Valve (ASV) - Federal

Remove air suction hoses from ASV and apply vacuum to diaphragm (top port). Blow air into port. Air should pass through valve with vacuum applied and should not pass through when vacuum is removed from diaphragm. If not, replace valve.

Vacuum Control Valve (VCV) - Federal

Disconnect vacuum hose from port "Z" and connect port "Z" directly to intake manifold vacuum source. (Scheme 13) Disconnect hoses from ports "S" and "X" of valve. With engine idling, place finger over port "X". Vacuum should not be present. Vacuum should be present momentarily as hose is reconnected to port "S". If not, replace valve.

Testing Vacuum Control Valve. Scheme 13

Vacuum Transmitting Valve (VTV) - Federal

Check VTV by blowing air into each side. Verify air flows without resistance from side B to side A. Air should flow with difficulty from side A to side B. If problem is found, replace valve.

Emission Control System (Carb.) - California. Scheme 14

Electronic Air Control Valve (EACV) - California

1. Disconnect AS hose from EACV. Disconnect connector from thermo switch (2) and ground it. Ensure a bubbling noise is not heard from Electronic Air Control Valve (EACV).
2. Reconnect connector to thermo switch (2). Disconnect connector from thermo switch (1) and ground it. Maintain engine speed at above 1390 RPM and check that a bubbling noise is intermittently heard from EACV.
3. Reconnect connector to thermo switch (1). If a problem is found, replace EACV.

Vacuum Switch - California

Using an ohmmeter, check that there is no continuity between switch terminal and switch body. Warm up engine to normal operating temperature. Using an ohmmeter, check continuity between switch terminal and body.

EBCV - California

1. Check for short circuit. Using an ohmmeter, check that there is no continuity between positive (+) terminal and EBCV body. If there is continuity, replace EBCV.
2. Check for open circuit. Using an ohmmeter, measure resistance between positive (+) terminal and other terminal. Resistance should be 11-13 at 68°F (20°C). If resistance is not as specified, replace EBCV.

Scheme 15

1. Check condition of all hoses and tubes. Remove air suction hose from air switching valve. Verify bubbling noise is heard from air switching valve at idle. (Scheme 15): Air Suction System (Federal)
2. Disconnect vacuum hose from air switching valve. Bubbling noise should not be heard from air switching valve at idle. Reconnect vacuum and air suction hoses.
3. To check vacuum control valve, race engine and quickly close throttle valve. Bubbling noise should stop momentarily. If system does not operate as outlined, check each component. See COMPONENT TESTS.

CALIFORNIA

1. Check condition of all hoses and tubes. Ensure coolant temperature is below 43°F (6°C). Start engine and ensure a bubbling noise is not heard from Electronic Air Control Valve (EACV).
2. Warm engine until coolant temperature is between 64-109°F (18-43°C). Maintain engine speed at 1390 RPM and check that a bubbling noise is heard from EACV.
3. Continue to run engine until coolant temperature is above 131°F (55°C). Maintain engine speed at 1390 RPM and check that a bubbling noise is intermittently heard from EACV.
4. Allow engine to return to idle and check that a bubbling noise is heard from EACV. With coolant temperature above 64°F (18°C) and engine under heavy load, disconnect vacuum hose from vacuum switch and plug end of hose. Ensure a bubbling noise is not heard from EACV.