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Test NTC-2: Checking EGR System

  1. Ensure ignition is off. Disconnect vacuum supply hose at EGR solenoid. EGR solenoid is located on top of EGR backpressure transducer which contains vacuum hose to EGR valve. See Fig 1 .
    Fig 1: Locating Typical EGR Solenoid & Components
    G98G00642Courtesy of DAIMLERCHRYSLER CORPORATION
  2. Install vacuum gauge on disconnected vacuum supply hose. Start engine and note vacuum reading with engine idling. If vacuum is more than 10 in. Hg at idle, go to next step. If vacuum is 10 in. Hg or less at idle, go to step  13 .
  3. Shut engine off. Disconnect vacuum gauge from vacuum supply hose. Reinstall vacuum supply hose on EGR solenoid. Disconnect vacuum hose from top of EGR valve.
  4. Start engine and allow engine to idle. With engine idling, using vacuum pump, slowly apply vacuum to EGR valve while listening for a decrease in engine speed. If engine speed decreases, go to next step. If engine speed does not decrease, go to step  9 .
  5. Shut engine off. Disconnect backpressure hose from signal tube at base of EGR valve. See Fig 1 .
  6. Using shop air, apply 20 psi (1.4 kg/cm2 ) air pressure on signal tube at base of EGR valve. Open and close throttle while listening for a tone change. If tone does not change, go to next step. If tone changes, replace EGR valve assembly. Perform TEST VER-2A  .
  7. Using vacuum pump, apply 10 in. Hg of vacuum to EGR valve. Vacuum should hold for at least 30 seconds. If vacuum is maintained for 30 seconds, go to next step. If vacuum cannot be maintained for 30 seconds, replace EGR valve assembly. Perform TEST VER-2A  .
  8. Disconnect vacuum hose from top of EGR valve. Install vacuum gauge on disconnected vacuum hose. Start engine. Disconnect EGR solenoid connector while observing vacuum gauge. If vacuum is more than 3 in. Hg, test is complete. If vacuum is 3 in. Hg or less, replace EGR valve assembly. Perform TEST VER-2A  .
  9. Shut engine off. Disconnect backpressure hose from signal tube at base of EGR valve. See Fig 1 .
  10. Using shop air, apply 20 psi (1.4 kg/cm2 ) air pressure on signal tube at base of EGR valve. Open and close throttle while listening for a tone change. If tone does not change, go to next step. If tone changes, replace EGR valve assembly. Perform TEST VER-2A  .
  11. Disconnect vacuum hose from top of EGR valve. Install vacuum gauge on disconnected vacuum hose. Start engine. Disconnect EGR solenoid connector while observing vacuum gauge. If vacuum is more than 3 in. Hg, go to next step. If vacuum is 3 in. Hg or less, replace EGR valve assembly. Perform TEST VER-2A  .
  12. Shut engine off. Remove EGR valve assembly. Inspect passages in EGR valve and intake manifold for restrictions. If all passages are not restricted, replace EGR valve assembly. Perform TEST VER-2A  . If passages are restricted, clean passages as necessary and reinstall EGR valve. Perform TEST VER-2A  .
  13. Shut engine off. Disconnect vacuum supply hose from intake manifold. Connect vacuum gauge to intake manifold. Start engine and allow engine to idle. Note vacuum reading with engine idling. If vacuum is more than 10 in. Hg at idle, repair restricted or leaking vacuum supply hose to EGR solenoid. Perform TEST VER-2A  . If vacuum is 10 in. Hg or less at idle, repair restricted vacuum supply passage on intake manifold. Perform TEST VER-2A  .
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