1983 Mercury Capri Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Integral Backpressure Transducer Valves

  1. Disconnect vacuum line to valve and plug. Connect vacuum pump to valve. Start engine and idle. Apply 6 in. Hg vacuum to valve. Vacuum should bleed off and valve should not operate.
  2. If vacuum holds and valve opens, replace valve. With engine at idle, there should be no vacuum to the valve. If so, check vacuum hose routing. With engine cold, there should be no vacuum to valve. If so, check TVS or PVS and replace as required.
  3. With engine warm, there should be vacuum to valve at 3000 RPM for 2.3L engines, and kickdown RPM on all other engines. If not, check vacuum lines from EGR to source.
  4. Clamp a suitable plug about 1/16" less in diameter than I.D. of tailpipe into end of tailpipe. A drive socket with drive hole covered may be used. Idle engine and apply vacuum gradually. Valve stem/diaphragm should move smoothly and engine idle should roughen.
    CAUTION: Do not block tailpipe fully and do not run engine faster than idle for prolonged periods. Be sure to remove plug from tailpipe at end of test. If these precautions are not followed, engine and/or exhaust system damage may occur.
  5. Trap 6 in. Hg vacuum and hold. Vacuum should drop more than 1 in. Hg in 30 seconds. If valve test is okay but engine does not idle rough in test, clean valve passages. If test is not okay, replace valve.
Factory Service Tools

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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.