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Home >> Lexus >> 1997 >> SC 300 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Emission Systems & Sub-Systems >> Exhaust Gas RECIRCULATION (EGR) Vacuum Modulator
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Exhaust Gas RECIRCULATION (EGR) Vacuum Modulator

  1. Turn engine off. Label and disconnect all vacuum hoses from EGR vacuum modulator. EGR vacuum modulator is mounted next to EGR valve. Block ports "P" and "R" with finger. See Figure.
  2. Blow air through port "Q". If air flows out of filter side freely, go to next step. If air does not flow out of filter side freely, replace EGR vacuum modulator.
  3. Start and raise engine speed to 2500 RPM. Block ports "P" and "R" with finger. Blow air through port "Q". There should be a strong resistance to airflow out of filter. Replace EGR vacuum modulator is it does not operate as specified.
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