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Negative BACKPRESSURE EGR Valve

  1. EGR negative backpressure valve may be identified by letter "N" in last position of EGR part number. With engine off, disconnect EGR valve vacuum signal hose. Connect vacuum pump to vacuum signal tube and apply 10 in. Hg.
  2. EGR diaphragm should move up and remain up for 20 seconds. If diaphragm does not stay up for 20 seconds, EGR valve is defective. Using an assistant, again apply 10 in. Hg to signal tube. Have assistant immediately try to start engine. Observe diaphragm for movement.
  3. If diaphragm moves to a seated position (valve closed) during cranking and initial starting, EGR valve is functioning properly. If diaphragm does not move, clean or replace EGR valve.
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