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Test NTC-13A - Checking EGR System

NOTE: For component location, see the THEORY/OPERATION article.
  1. Turn ign off. Inspect condition and routing of all EGR hoses. Repair or replace hoses as necessary and perform TEST VER-2A . If hoses are okay, go to next step.
  2. Disconnect vacuum supply hose at EGR solenoid. Connect vacuum gauge to disconnected vacuum hose. Start engine. If vacuum is more than 10 in. Hg at idle, go to step 4). If vacuum is 10 in. Hg or less at idle, go to next step.
  3. Disconnect EGR vacuum supply hose at intake manifold. Connect a vacuum gauge to intake manifold nipple. Read vacuum gauge at idle. If vacuum is more than 10 in. Hg at idle, repair restriction or leak in vacuum line to EGR solenoid and perform TEST VER-2A. If vacuum is 10 in. Hg or less at idle, repair plugged vacuum nipple at throttle and perform TEST VER-2A.
  4. Disconnect vacuum gauge, and reconnect vacuum hose to EGR solenoid. Disconnect vacuum hose from EGR valve, and connect vacuum gauge to disconnected hose. Go to next step.
  5. While observing vacuum gauge, momentarily snap throttle open. If vacuum is not more than 5 in. Hg at any time, replace EGR valve assembly and perform TEST VER-2A . If vacuum is more than 5 in. Hg at any time, go to next step.
  6. Turn ignition off. Disconnect hose to EGR valve exhaust backpressure tube. Adjust a shop air hose to 20 psi. Connect shop air to nipple on base of backpressure transducer. Listen for a tone change while opening and closing throttle. If tone changes, replace EGR valve assembly and perform TEST VER-2A. If tone does not change, go to next step.
  7. Remove vacuum gauge. Cap open nipple on base of backpressure transducer. Connect hand vacuum pump to EGR valve. Start engine and go to next step.
  8. While slowly applying vacuum to EGR valve, listen for engine RPM change. If engine RPM does not change, replace EGR valve assembly and perform TEST VER-2A . If engine RPM changes, go to next step.
  9. Turn ignition off. Apply 10 in. Hg and hold for 30 seconds. If vacuum does not hold for 30 seconds, replace EGR valve assembly and perform TEST VER-2A. If vacuum holds for 30 seconds, EGR system is normal. Test passed.
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