Boost Pressure
- To test the turbocharging system, use a pressure gauge (VW 1397). The gauge is equipped with a valve which locks pressure measurement when closed.
- Attach gauge to vacuum advance at distributor, using "T" fitting supplied with gauge. Be sure vacuum advance unit and charcoal canister purge valve are free of leaks. Use hose clamps at all connections to avoid low readings.
- Boost pressure can only be tested on a chassis dynamometer or through road testing. Carry the gauge inside car by routing the hose out right rear corner of hood and into passenger side vent wing window.
- Accelerate engine to full throttle in drive position "1". Hold vehicle speed constant with foot brake, when engine speed reaches 5500 RPM. Wait 2 seconds and close gauge valve by pulling sleeve away from dial.NOTE: Testing should not exceed 10 seconds at full boost.
- Boost pressure readings will vary with atmospheric pressure, temperature, and altitude. See Boost Pressure Specifications table. If boost pressure is too high, wastegate is defective. If boost pressure is too low, replace defective turbocharger.
BOOST PRESSURE SPECIFICATIONS
| Ambient Temperature | psi (kg/cm2 ) |
|---|---|
| 32°F (0°C) | 7.3-7.9 (.50-.54) |
| 50°F (10°C) | 7.0-7.7 (.48-.52) |
| 68°F (20°C) | 6.7-7.5 (.46-.51) |
| 77°F (25°C) | 6.6-7.3 (.45-.50) |
| 86°F (30°C) | 6.4-7.1 (.44-.49) |
NOTE:
The boost pressure gauge in the instrument cluster is calibrated to read absolute pressure. When the engine is not running and gauge reads "1", this is normal atmospheric pressure. A reading of over "1" indicates boost pressure in the intake manifold; a reading less than "1" indicates presence of vacuum.