Intake Air Control Valve
- Remove throttle body. See THROTTLE BODY
under FUEL SYSTEM in REMOVAL & INSTALLATION - EXCEPT GX470 article. Remove upper and lower intake manifolds. See KNOCK SENSOR
under SENSORS & SWITCHES in REMOVAL & INSTALLATION - EXCEPT GX470 article. Install a 3-way vacuum "T" fitting in vacuum hose between Intake Air Control Valve (IACV) actuator and ACIS Vacuum Switching Valve (VSV). See Fig 1. Reinstall intake manifolds and throttle body.
- Connect a vacuum gauge to vacuum "T" fitting. Start engine. With engine idling, ensure vacuum reading is about 11.8 in. Hg, and IACV actuator rod is pulled out. Snap accelerator to Wide Open Throttle (WOT) position. Vacuum should not exist during WOT and IACV actuator rod should return. If vacuum is not as specified or actuator valve rod fails to pull out, go to next step.
- Remove IACV. Apply about 11.8 in. Hg to IACV actuator. If IACV actuator rod does not move, replace IACV actuator. If IACV actuator rod moves, check to see if diaphragm holds vacuum for at least one minute. If diaphragm does not hold vacuum, replace actuator. If diaphragm holds vacuum, check vacuum hoses and vacuum tank. See ACIS VACUUM TANK .
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