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Home >> Oldsmobile >> 1990 >> Custom Cruiser >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Exhaust Gas RECIRCULATION (EGR) >> Pulse Width Modulated EGR Valve
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Pulse Width Modulated EGR Valve

  1. Place transmission in Park or Neutral. With engine at idle and at normal operating temperature, push up on EGR valve diaphragm. Engine RPM should drop. If engine RPM did not drop, clean EGR valve and passages.
  2. Check EGR valve movement with engine RPM change from 2000 RPM to idle. If EGR valve moves with RPM change, check Park/Neutral switch adjustment or open circuit. If EGR valve did not move, ground ALDL test connector. If EGR valve moves now, EGR valve is functioning properly. If not, go to next step.
  3. Turn engine off and disconnect EGR solenoid connector. Connect 12-volt test light between EGR solenoid connector terminals. Turn ignition on and ground ALDL test connector. Test light should flash repeatedly.
  4. If test light flashes, check vacuum to EGR solenoid at 2000-3000 RPM. If engine does not use a vacuum regulator, at least 7 in. Hg should be present at solenoid. If engine is equipped with a vacuum regulator, 2-10 in. Hg should be present.
  5. If vacuum is greater than 10 in. Hg, replace regulator. If vacuum is less than 2 in. Hg, vacuum at solenoid is okay. Check EGR solenoid connections and/or faulty EGR solenoid.
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