Intake Air Control Valve System
NOTE:
Intake Air Control Valve (IACV) system may also be referred to as Acoustic Control Induction System (ACIS).
- Using "T" connector, connect vacuum gauge in vacuum line to actuator valve, located at end of air intake chamber. See Fig 1. Start engine. With engine idling, ensure no vacuum reading is obtained.
- Fully open throttle and ensure vacuum reading momentarily reads approximately 8 in. Hg and actuator valve rod pulls inward. If actuator valve rod pulls inward, system is operating correctly. If actuator valve rod does not pull inward, proceed to next step.
- Disconnect vacuum hose from actuator valve. Using vacuum pump, apply 8 in. Hg of vacuum to actuator valve. Ensure actuator valve rod pulls inward and remains pulled inward for at least one minute. Replace actuator valve if defective. If actuator valve operates correctly, reconnect vacuum hose. Proceed to next step.
- Disconnect hoses from vacuum tank located near driver's side front corner of engine compartment, below battery tray. Apply air pressure to port "B" on vacuum tank. Ensure air flows from port "A". Perform STEP 1. See Fig 2. Apply air pressure to port "A". Ensure air does not flow from port "B". Perform STEP 1. See Fig 2.
- Plug port "B" on vacuum tank. Using vacuum pump, apply 8 in. Hg of vacuum to port "A". Perform STEP 2. See Fig 2. Ensure vacuum reading will hold for at least one minute. Replace vacuum tank if defective and recheck system operation. If vacuum tank is okay, reconnect vacuum hoses. Proceed to next step.
- Remove "V" bank cover located on top of engine. See Fig 3. Disconnect electrical connector and vacuum hoses from intake air control valve Vacuum Switching Valve (VSV) located near valve cover. See Fig 3.NOTE: It may be necessary to remove emission control valve set which contains various vacuum switching valves for access to intake air control valve VSV.
- Using ohmmeter, check that continuity exists between electrical terminals on intake air control valve VSV and that resistance is 33-39 ohms at 68°F (20°C). Replace intake air control valve VSV if no continuity exists or resistance is not within specification.
- Ensure no continuity exists between each electrical terminal and body of intake air control valve VSV. Replace intake air control valve VSV if continuity exists between electrical terminal and body of intake air control valve VSV.
- Apply air pressure to port "B". Ensure air flows from the filter. Perform STEP 1. See Fig 4. Apply battery voltage and ground to electrical terminals on intake air control valve VSV. Apply air pressure to port "B". Ensure air flows from port "A". Perform STEP 2. See Fig 4. Replace intake air control valve VSV if defective. Recheck system operation.
- If intake air control valve VSV is okay, reinstall VSV. Remove glove box for access to Engine Control Module (ECM). Turn ignition on. Using voltmeter, check voltage between terminal No. 6 (Red/Yellow wire) on ECM and chassis ground. See Fig 5.
- Voltage should be 9-14 volts. If voltage is not within specification, check for defective EFI main relay or wiring harness between EFI main relay and ECM. See EFI main relay under RELAYS. See appropriate wiring diagram in WIRING DIAGRAMS article.
- If EFI main relay and wiring harness are okay, check ECM ground circuit. If ECM ground circuit is okay, substitute another ECM and recheck system operation.