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Home >> Isuzu >> 1997 >> Oasis LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Idle Control System >> Fast Idle THERMO Valve
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Fast Idle THERMO Valve

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 air flow. If airflow exists, go to next step. If airflow does not exist, replace fast idle thermo valve and retest.
  2. Start engine and run at 3000 RPM with no loads and transmission 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 for air in cooling system. If cooling system is okay, replace fast idle thermo valve and retest.