1988 Ford Taurus MT5FACTORY OEM SERVICE PROCEDURE

Backpressure Variable Transducer (BVT) EGR System

  1. Ensure vacuum system is correctly routed and in serviceable condition. Start and ensure there is no vacuum to EGR valve at idle (engine at normal operating temperature). Install a tachometer.
  2. Disconnect ISC connector (MPFI and SEFI engines). Disconnect and plug vacuum supply hose from EGR valve nipple. Ensure engine idle speed is within specification.
    Fig 1: Backpressure Variable Transducer (BVT)
    G55796
  3. 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). If speed does not drop, replace EGR valve. If speed drops, release vacuum and ensure engine speed returns to normal +/-25 RPM.
  4. Reconnect ISC connector and EGR supply hose. Disconnect vacuum connection at BVT. See Fig 1 . Lightly blow into the hose to port "A" until relief valve closes and at the same time apply 5-10 in. Hg of vacuum to port "C", using a hand vacuum pump. Port "C" should hold vacuum as long as there is pressure to port "B".
  5. Apply 5-10 in. Hg vacuum to ports "A" and "B". These ports should hold vacuum. Replace transducer if any ports do not hold vacuum. Reconnect vacuum hoses to BVT ports.
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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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