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Home >> Lexus >> 1992 >> SC 400 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Emission Systems & Sub-Systems >> Exhaust Gas RECIRCULATION (EGR) >> EGR Vacuum Modulator Check
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EGR Vacuum Modulator Check

  1. Turn engine off. Label and disconnect all vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" with finger (twin ports on side of modulator). See Figure. Blow air into port "Q" (single port on side of modulator). Air should flow freely out of filter.
  2. Start engine, and run it at 2500 RPM. Block ports "P" and "R" with finger. Blow air into port "Q". Air should not flow out of filter. If air flows out of filter, replace EGR vacuum modulator.
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