Boost Pressure Regulation, Checking

Boost pressure regulation, checking

Recommended special tools and equipment e.g.:






- V.A.G 1397 A Turbocharger Tester

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

Test sequence

Charge pressure is measured under Wide Open Throttle (WOT) while driving or on a dynamometer.






- Disconnect connection hose between intake manifold and deceleration shut-off valve at intake manifold and connect to T-piece of V.A.G 1397 A turbocharger tester.

- Switch on measurement range I.

Note:
- Using turbocharger tester, see operating instructions.
- The hoses must be connected absolutely free of leaks.
- When charge pressure is measured during the drive, a second person is necessary to operate the turbocharger tester for safety reasons.
- Make sure that the pressure hose is not pinched between engine hood and chassis.

- Measure charge pressure at Wide Open Throttle (WOT):

On dynamometer

In 3rd gear or in 2nd drive mode

While driving

Vehicles with manual transmission:

- Accelerate vehicle at Wide Open Throttle (WOT) in 2nd gear

Vehicles with automatic transmission:

- Manually (Tiptronic) shift vehicle in 4th gear and accelerate vehicle from low speed at Wide Open Throttle (without kick down, transmission does not downshift any more).

- Between 1800 to 2300 RPM, press the "M" memory button on turbocharger tester and read out the test value.

Specified value: (absolute pressure) 1.350 ... 1.750 bar

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

If boost pressure is exceeded:

- Check Wastegate Bypass Regulator Valve -N75-. (Throughput in hose from turbocharger via valve to vacuum diaphragm with connector disconnected)

- Check for proper seating of vacuum diaphragm for wastegate bypass regulator valve at bypass regulator valve at turbocharger.

- Check vacuum diaphragm.

- Check bearing for shaft of wastegate bypass regulator valve in turbocharger for ease of movement. If rusted solid, replace turbocharger.

If boost pressure is not reached:

- Check wastegate bypass regulator valve -N75-.

- Check bearing for shaft of wastegate bypass regulator valve in turbocharger for ease of movement. If rusted solid, replace turbocharger.

- Turbocharger faulty, replace.