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Home >> Audi >> 1994 >> S4 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Air Induction Systems >> Turbocharger & WASTEGATE Checking >> Road Test

Road Test

  1. Fully depress accelerator pedal in 4th gear at a road speed of approximately 37 MPH, and watch tachometer.
  2. Press M button on turbocharger tester when tachometer reads 3000 RPM. FigureObserve the boost pressure (bar). See Fig 1.
    3. NOTE: Boost pressure values may vary slightly for intermediate values of outside temperatures. DTC memory may indicate "MANIFOLD ABSOLUTE PRESSURE SENSOR -G71- CONTROL DIFFERENCE" when the temperature is below 32°F (0°C) and the vehicle driven in an average speed range. Disregard the display and erase DTC memory.
  3. If specified value is okay, but poor performance occurs in speed range below 2300 RPM, check by-pass valve. See BY-PASS VALVE .
  4. If specified value is NOT okay, temporarily replace wastegate and repeat check.
  5. If specified value is still NOT okay, replace turbocharger.
Fig 1: Boost Pressure Value Reference Chart
G00177368Courtesy of AUDI OF AMERICA, INC.
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