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Home >> Honda >> 2001 >> Prelude Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Idle Control Systems >> Fast Idle THERMO Valve (Prelude)
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Fast Idle THERMO Valve (Prelude)

NOTE: Fast idle thermo valve is adjusted by manufacturer and should not be disassembled.
  1. Remove intake air duct from throttle body. Ensure engine coolant temperature is less than 86°F (30°C). Start engine and allow to idle. Place finger over lower port in throttle body and check for airflow. If airflow exists, go to next step. If airflow does not exist, replace fast idle thermo valve and retest.
  2. Hold engine speed at 3000 RPM under no load with transaxle in Park or Neutral, until radiator fan comes on. Allow engine to idle. Verify fast idle thermo valve is completely closed. If valve is leaking, engine idle speed will decrease when lower port in throttle body is covered. If valve is leaking, check engine coolant level and check for air in cooling system. If cooling system is okay, replace fast idle thermo valve and retest.
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