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Ported EGR Valve

  1. Ensure vacuum system is correctly routed and in serviceable condition. There should be no vacuum to EGR valve at idle (engine at normal operating temperature). Disconnect ISC connector. Install a tachometer.
  2. Disconnect and plug vacuum supply hose from EGR valve nipple. Start engine and ensure engine idle speed is within specification. Using a hand pump, slowly apply 5-10 in. Hg vacuum to EGR valve. With vacuum applied, idle speed should drop about 100 RPM (engine may stall).
  3. If speed does not drop, replace EGR valve. If speed drops, release vacuum and ensure engine speed returns to normal +/-25 RPM. Reconnect ISC connector and EGR supply hose.
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