Boost Pressure Control DDE 3.0

A turbocharger with variable turbine geometry and without a wastegate is used for boost pressure control. It is operated by means of an adjustment lever on the turbine housing. The adjustment lever is connected by means of a control rod to the vacuum unit on the turbocharger such that the control rod is extended and retracted corresponding to the vacuum applied.

Components

• Turbocharger with variable turbine geometry
  
• Vacuum unit with control rod
  
• Pressure converter
  

Function

The pressure converter links the vacuum unit with the vacuum supply by means of hoses and, depending on the activation status, it switches a variable vacuum to the vacuum unit controlled by the DDE control unit. In this way, the control rod is set in the required position. The pressure converter is activated by a square-wave signal with duty factors (= variable pulse width) between 5 and 95 %.

Checking variable turbine geometry

• Maximum stroke of control rod: 10 mm
  
• The control rod must be fully RETRACTED (= maximum boost pressure) at 650 mbar vacuum applied at the vacuum unit.
  
• The control rod must be fully EXTENDED (= minimum boost pressure) at 0 mbar vacuum applied at the vacuum unit.
  

Troubleshooting

Fault code 65 "turbocharger control" is stored in the event of impermissible control deviation or fault "short/open circuit in pressure converter activation".

Consequences:

• Boost pressure control is deactivated
  
• Exhaust gas recirculation is deactivated
  
• The injection volume is limited to 25 mg/stroke in the event of negative control deviation in the boost pressure
  

Boost pressure control is also deactivated if following faults occur:

• Fault code 06: Exhaust gas recirculation (positive control deviation)
  
• Fault code 36: Boost pressure sensor