EGR System

1985 Toyota Tercel DX, 4D Wagon, FWD, AutomaticSECTION EGR System
  1. Check and clean vacuum modulator filters with compressed air before proceeding with test. Disconnect vacuum hose from EGR valve and, using a "T" connector, connect a vacuum gauge. Check that engine starts and runs at idle.
  2. Check TVSV with coolant temperature below 122°F (50°C). Check that vacuum gauge indicates zero at 3000 RPM.
    Fig 1: EGR System
    G38398Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Check TVSV and EGR vacuum modulator with engine hot. Vacuum gauge should indicate low vacuum at 3000 RPM.
  4. With engine idling, apply vacuum directly to EGR valve. Engine should run rough or die. Remove vacuum and reconnect vacuum hoses to proper locations. Engine should run smooth. If no problem is found with this inspection, system is okay.
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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.