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Port EGR Valve

  1. Turn ignition off. Disconnect vacuum hose at vacuum signal tube of EGR valve. Connect a vacuum pump to vacuum signal tube and apply 10 in. Hg vacuum. EGR diaphragm plate should move up and remain up for at least 20 seconds.
  2. If diaphragm moves up and holds for 20 seconds, diaphragm is operating properly. If diaphragm does not hold vacuum, replace EGR valve. Place transmission in "PARK" or "NEUTRAL" and connect vacuum pump to EGR valve.
  3. With engine running at normal operating temperature, push up on diaphragm. Engine RPM should decrease. If RPM decreases, EGR valve is functioning properly. If engine RPM does not decrease, replace EGR valve. If further testing is required, see appropriate diagnostic chart in COMPUTER COMMAND CONTROL article.
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