Hot Engine
- Warm engine to operating temperature. Check operation of thermovalve C. Attach vacuum gauge to vacuum hose No. 27 at tubing manifold. There should be no vacuum at idle. If there is no vacuum, check air suction valve. If there is vacuum, replace thermovalve C and retest.
- To check air suction valve, remove air cleaner cover and filter. Start engine and run at idle speed. Check for bubbling noise from air suction port. See Fig 1 . If bubbling noise is heard, proceed to step 3).
- If bubbling noise is not heard, disconnect hose No. 5 from air suction cut-off diaphragm and check for vacuum. If vacuum is present, replace air suction cut-off diaphragm and retest. If no vacuum is present, reconnect vacuum hose No. 5.
- Disconnect hose No. 32 from control box at vacuum hose manifold and check for vacuum at vacuum hose manifold. There should be vacuum. If there is no vacuum, check vacuum hose No. 32 for blockage or leakage. If okay, replace air bleed valve B and retest.
- If there is vacuum, check for voltage at air suction control valve in box No. 1 (Blue/Green wire on man. trans. and Green/Red wire on auto. trans.). If there is no voltage, check intake air temperature sensor and vacuum switch C.
- Check for voltage at control unit Black/Yellow wire with ignition on. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. It should have continuity.
- If voltage is present, replace air suction control valve and retest. Raise engine speed above 3500 RPM. If a bubbling noise is not heard, system is okay. If bubbling noise is heard, check for voltage at air suction control solenoid valve (Green/Red wire on auto. trans. and Blue/Green wire on man. trans.) in box No. 1.
- If there is voltage, check intake air temperature sensor and vacuum switch C. Check for voltage at control unit Black/Yellow wire with ignition on. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. It should have continuity.
- If there is no voltage, replace the air suction control solenoid valve and retest. Heat air bleed valve to 140°F (60°C). Ensure bubbling noise stops. If not, replace air bleed valve B.