Intake Air Bypass Control System

1. Start the engine. Hold the engine at 3,000 rpm with no load in Park or neutral until the radiator fan comes on.




2. Disconnect the vacuum hoses and connect vacuum pump to the hoses individually.
3. Allow the engine to idle, and check the vacuum.
- If no vacuum, check the vacuum hose routing of the intake air bypass control system.
- If the vacuum, check the IAC Valve, the Idle Air Control Thermal Valve and the intake manifold port. If the intake manifold port is clogged, clean it with carburetor cleaner.