Boost Pressure Regulation, Checking

Boost Pressure Regulation, Checking

Recommended Special Tools, Workshop Equipment, Testers, Measuring Instruments and Auxiliary Items







- V.A.G 1397 A Turbocharger Tester

Test Conditions
- No leaks on intake or exhaust side.
- Engine oil temperature at least 80 degrees C

Test Sequence

CAUTION: To reduce the risk of accident during road tests, always observe safety precautions.

Charge pressure is measured under Wide Open Throttle (WOT) while driving or on the roller type test stand.







- Using V.A.G 1397A Turbocharger Tester test hose, connect T-piece to front of intake manifold.
- Guide test hose over rear corner of hood and through right window into vehicle interior.







- Switch turbocharger test device on and place measurement range switch in - I - position (absolute pressure).
- Connect test hose to connection - I -.

NOTE:
- Using turbocharger tester, see operating instructions.
- Hose lines must be connected with absolutely no leaks; otherwise, test malfunctions are possible.
- Ensure test hose is not pinched at hood and side window.
- By pressing memory button M on turbocharger tester, the last test value is saved until either memory button M is pressed again or the turbocharger tester is shut-off.
- The storage is indicated by blinking commas in the display field.
- If the turbocharger test device battery voltage falls below the permitted level, an arrow appears in the upper left corner of the display.
- Quickly drive at least 3 km before testing the vehicle (without traffic light stops and the like).
- A second technician is required because the indicated values must be read out during vehicle operation.

- Accelerate vehicle in 3rd gear at full throttle from 2000 RPM and watch tachometer.
- At about 3000 RPM, press the memory button - M - on V.A.G 1397 A.







- Specified value on V.A.G 1397 A : 1.700 to 1.900 bar positive pressure

NOTE: Repeat measurement if full charge pressure has not yet built up.

If the boost pressure is exceeded:
- Wastegate Bypass Regulator Valve -N75-, checking. (Throughput in hose from turbocharger via valve to vacuum diaphragm with connector disconnected)
- Check that vacuum diaphragm for charge pressure regulator valve is securely seated on turbocharger.
- Check vacuum diaphragm, Vacuum Diaphragm For Boost Pressure Regulator Valve, Checking
- Check the mounting of the boost pressure regulator valve shaft in the turbocharger for ease of movement.

If rusted in place, replace turbocharger.

If boost pressure is not reached:
- Wastegate Bypass Regulator Valve -N75-, checking.
- Check the mounting of the boost pressure regulator valve shaft in the turbocharger for ease of movement.

If rusted in place, replace turbocharger.
- Turbocharger faulty, replace.