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Home >> Geo >> 1995 >> Prizm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 1.6L >> Emission Systems & Sub-Systems >> Exhaust Gas RECIRCULATION >> EGR Vacuum Modulator Check
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EGR Vacuum Modulator Check

  1. Remove 3 upper vacuum hoses from EGR modulator. Using fingers, plug modulator paired ports NO's. 2 and 3, and blow air into opposite port. Air should pass freely through filter.
  2. Start engine and hold speed to 2500 RPM. Using fingers, plug modulator paired ports and blow air into opposite port No. 1. See Figure . There should be a strong resistance to air flow. Replace EGR vacuum modulator if it does not operate as specified.