Charge pressure control (Vehicles With E-Gas System), checking

Charge pressure control, checking (vehicles with E-Gas system)
Special tools and equipment
^ VAG1551 Scan Tool (ST) or VAG1552 mobile scan tool with VAG1551/3 adapter cable.

Test requirements
^ No leaks on intake and exhaust side.
^ Engine oil temperature at least 80° C.

Test sequence
- Connect VAG1551 (VAG1552) scan tool. Start engine and select Engine Control Module (ECM) via "address word" 01.





Indicated on display:

- Press buttons -0- and -8- to select function "Read measuring value block" and press -Q button to confirm input.





Indicated on display:

- Press buttons -1-, -1- and -4- to select "display group number 114" and press -Q- button to confirm input.





Indicated on display

- During a road test or on a dynamometer (at Wide Open Throttle between 1800 and 2300 RPM), check the duty cycle of solenoid valve for Charge pressure control in display field 4
Specified value: 5 to 95%
If specified value is obtained:
- Press-C- button
- Press buttons -1-, -1- and -5- to select "display group number 115" and press -Q- button to confirm.





Indicated on display

- Check actual boost pressure value in display field 4 at Wide Open Throttle (WOT):

On dynamometer
In 3rd gear or in 2nd drive mode

While driving
Vehicles with manual transmission
- Accelerate vehicle in 2nd gear at Wide Open Throttle (WOT).
Vehicles with automatic transmission
- Manually select (Tiptronic) the 4th gear and accelerate the vehicle from low speed at Wide Open Throttle (WOT) (without kick down, the transmission will not downshift).
- Press print button between 1800 and 2300 RPM and read the actual boost pressure value in display field 4.
Specified value: 1350 to 1750 mbar
- Compare actual boost pressure value to specified value in display field 3.
Deviation: max. 100 mbar

Note: Repeat measurement if the full boost pressure has not yet built up or if the deviation between specified and actual value is too large.

If boost pressure is exceeded:
- Check charge air pressure sensor -G31-, Refer to Fuel Delivery and Air Induction.
- Check wastegate bypass regulator valve -N75-. (throughout in hose from turbocharger via valve to vacuum diaphragm with connector disconnected)
- Check vacuum diaphragm for proper seating at turbocharger.
- Check recirculating valve for turbocharger.
- Check bearing for shaft of wastegate bypass regulator valve in turbocharger for ease of movement. If rusted solid, replace turbocharger.

If lower limit for boost pressure is not met:
- Check charge air pressure sensor -G31-, Refer to Fuel Delivery and Air Induction.
- 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 malfunctioning, replace.