Audi Workshop Service and Repair Manuals

Checking turbocharger and charge pressure regulating valve - vehicles with electronic throttle Special tools and workshop equipment required

t  Turbocharger tester -V.A.G 1397 A-

t  Vehicle diagnosis, testing and information system -VAS 5051- Procedure l  All hoses and pipes securely fitted and and free of leaks. l  Fault memory interrogated and final control diagnosis performed → Rep. Gr.01.   WARNING To avoid accident risks when road testing the vehicle with test equipment, always observe the relevant safety precautions → Chapter.

–  Take off engine cover panel -arrows-.

–  Connect T-piece with test hose of turbocharger tester -V.A.G 1397 A- to intake manifold (front). –  Route test hose under rear edge of bonnet and through right window into passenger compartment.

–  Switch on turbocharger tester and set measuring range selector switch to position -I- (absolute pressure). –  Attach test hose to connection -I-.   Note t  Ensure absolute leakproof connection of hoses to avoid measurement errors. t  Take care not to trap test hose at bonnet and side window. t  Pressing memory button -M- on turbocharger tester causes last measured value to be stored until memory button -M- is pressed again or tester is switched off. t  The decimal point in the display flashes to indicate that the value is being stored. t  If the battery voltage of the turbocharger tester drops below the minimum level, an arrow will appear at the top left of the display. t  Before performing the test, drive vehicle moderately fast for at least 3 km (without stopping at traffic lights etc.).

–  Connect up vehicle diagnostic, testing and information system -VAS 5051- with diagnosis lead -VAS 5051/1-, press vehicle self-diagnosis key and select vehicle system “01 - Engine electronics”. Engine must be idling.

Display on -VAS 5051-: –  From the list -1- select diagnostic function “08 - Read measured value block”.

Display on -VAS 5051-: –  Press keys 115 on keypad -2- to select “Display group 115” and confirm entry by pressing key Q. 1 -  Enter display group

Vehicles with engine code AQA, ARX, ARZ, AUM: –  Accelerate vehicle in 3rd gear from 2000 rpm at full throttle while a second mechanic observes the rev counter. –  Have the second mechanic press PRINT key on -VAS 5051- and memory key -M- on -V.A.G 1397 A- simultaneously at approx. 2500 rpm.   Note The charge pressure should be measured using turbocharger tester -V.A.G 1397 A-. Vehicle diagnostic, testing and information system -VAS 5051- is used to check whether the charge pressure is being registered by the control unit. l  Specification on -V.A.G 1397 A-: 1.500 ... 1.650 bar.

l  Specification on -VAS 5051- in display zone - 4-: 1500 ... 1650 mbar.

Vehicles with engine code AJQ, APP: –  Accelerate vehicle in 3rd gear from 2000 rpm at full throttle while a second mechanic observes the rev counter. –  Have the second mechanic press PRINT key on -VAS 5051- and memory key -M- on -V.A.G 1397 A- simultaneously at approx. 2800 rpm.   Note The charge pressure should be measured using turbocharger tester -V.A.G 1397 A-. Vehicle diagnostic, testing and information system -VAS 5051- is used to check whether the charge pressure is being registered by the control unit. l  Specification on -V.A.G 1397 A-: 1.800 ... 1.900 bar.

l  Specification on -VAS 5051- in display zone - 4-: 1800 ... 1900 mbar.

Vehicles with engine code : ARY, AUQ: –  Accelerate vehicle in 3rd gear from 2000 rpm at full throttle while a second mechanic observes the rev counter. –  Have the second mechanic press PRINT key on -VAS 5051- and memory key -M- on -V.A.G 1397 A- simultaneously at approx. 2800 rpm.   Note The charge pressure should be measured using turbocharger tester -V.A.G 1397 A-. Vehicle diagnostic, testing and information system -VAS 5051- is used to check whether the charge pressure is being registered by the control unit. l  Specification on -V.A.G 1397 A-: 1.600 ... 1.700 bar.

l  Specification on -VAS 5051- in display zone - 4-: 1600 ... 1700 mbar. All models: –  Press the ← key to exit from the function “08 - Read measured value block”. If the specification is obtained: –  Press function “06 - End output”. –  Switch off ignition and detach diagnostic connector. If specification is not obtained: –  Find fault causes using fault table below.

Fault	Possible causes
Charge pressure below specification	t  Hose connections to charge pressure control solenoid valve -N75- defective. Connection diagram → Chapter t  Charge pressure control solenoid valve -N75- defective. Checking → Chapter t  Charge pressure regulating valve in turbocharger stuck in open position. Renew turbocharger → Chapter t  Leak between turbocharger and intake manifold (air intake hoses and vacuum hoses) t  Mechanical air recirculation valve defective. Checking → Chapter t  Turbocharger air recirculation valve -N249- defective. Checking → Chapter t  Turbocharger defective. Renewing → Chapter
Charge pressure above specification	t  Air leaks in hoses or connections to vacuum unit for charge pressure control (via -N75-). Connection diagram → Chapter t  Vacuum unit for charge pressure regulating valve defective. Renew turbocharger → Chapter t  Charge pressure regulating valve in turbocharger sticking in closed position. Renew turbocharger → Chapter