1988 Pontiac Fiero Formula, AutomaticFACTORY OEM SERVICE PROCEDURE

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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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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