Turbocharger and Charge Pressure Control Valve, Checking
Turbocharger And Charge Pressure Control Valve, Checking
Special tools, testers and auxiliary items required
- Turbocharger tester VAG1397A
- VAS5051 with VAS5051/1
or
- VAG1551 with VAG1551/3A
Requirements
- All hoses and lines must be securely installed and free of leaks.
- Diagnostic Trouble Code (DTC) memory has been checked.
- Output Diagnostic Test Mode performed
- Vehicle Diagnostic, Testing and Information System VAS5051 or Scan Tool VAG1551 must be connected.
Work sequence
CAUTION:
- Always attach testers and measuring instruments to back seat and have them operated from there by a second person.
- If testers and measuring instruments were to be operated from front passengers seat, person sitting there could suffer injury in the event of an accident due to triggering of front passengers airbag.
- Connect T-piece and measuring hose of turbocharger tester VAG1397A to intake manifold (front).
- Route measuring hose under rear edge of hood and into passenger compartment via right side window.
- Switch on turbocharger tester and set measuring range selector switch to position -I- (absolute pressure).
- Connect measuring hose to connection -I-.
NOTE:
- Hose connections must be completely airtight, otherwise measurements will not be correct.
- Ensure that measuring hose is not pinched at hood or side window.
- Pressing memory key -M- on turbocharger tester will store last measured value until memory key -M- is pressed again or tester is switched off.
- The decimal point in display flashes to indicate that value is being stored.
- If battery voltage of turbocharger tester drops below minimum level, an arrow will appear at top left of display.
- Before performing test, drive vehicle at brisk speed for at least 3 km without stopping (i.e. along route without traffic lights, etc.).
- A second mechanic is required to note readings on tester when vehicle is moving.
Reading measured value block 115 -->
1 2 3 4
- Read measured value block, display group 115, engine idling.
- Accelerate vehicle from 2000 RPM to wide open throttle in third gear and watch rev counter.
- At approx. 2500 RPM, press print key on VAS5051 or PRINT key on VAG1551 while simultaneously pressing memory key -M- on VAG1397A.
NOTE:
- The charge air pressure should be measured using turbocharger tester VAG1397/A. Vehicle diagnostic, testing and information system VAS5051 or scan tool VAG1551 is used to check whether charge air pressure is being registered by control module.
- Specification for VAG1397A : 1.500 to 1.600 bar
- Specification on VAG1551 or VAS5051 in display zone 4:
Reading measured value block 115 -->
1 2 3 4
1500 to 1600 mbar
If reading does not match specification, troubleshooting table.
Malfunctions in charge air pressure control
Malfunction Possible cause of trouble
Charge air - Wastegate bypass regulator
pressure below valve
specification N75 faulty. Testing and Inspection
- Hoses to Wastegate bypass regulator valve N75 faulty.
- Charge pressure control valve in turbocharger sticking in open position
- Leak between turbocharger and intake manifold, effects
- Mechanical air recirculation valve faulty, checking
- Recirculating valve for turbocharger N249 faulty, checking Recirculating Valve For Turbocharger N249 , Checking
- Turbocharger faulty, replacing
Charge air - Vacuum unit for charge air
pressure above pressure control valve faulty, replacing
specification * - Hoses to vacuum unit for charge air pressure control (via N75 leaking, connection diagram or connection diagram
- Charge air pressure control valve in turbocharger sticking in closed position, replacing
* If charge air pressure is too high, fuel supply will be interrupted in order to protect engine. This results in misfiring at high engine speeds.