Turbocharger pressure adjuster DDE 5.1

Two variable nozzle turbine chargers without a ”wastegate” are used for turbo pressure control.

Control levers on the turbine housings activate the adjustable guide vanes in the turbines. The control levers are operated by electrical actuators (electric motors with worm gear and electronic control) that are mounted directly on the turbochargers. The actuators cannot be replaced separately.

Turbocharger pressure adjuster 1 is located in the direction of travel on the right.

Components

• Turbochargers with variable nozzle turbines and electric actuators
  

Function

The DDE master control unit activates turbocharger pressure adjuster 1; the DDE slave control activates turbocharger pressure adjuster 2. The turbocharger pressure adjusters are activated with square-wave signals with pulse duty factors (= changeable pulse widths) between 5% and 95%.

Checking variable turbine geometry

The control levers must move between minimum and maximum activation by 35° to 45° angle of rotation. Adjustment must take place rapidly.

Troubleshooting

The charge-air-pressure control is monitored for the following faults:

• Positive and negative control deviation
  
• Faults in activation of the turbocharger pressure adjusters
  
• Defects in the turbocharger pressure adjusters, e.g. blocked or electrically defective
  
• Charge air hoses disconnected
  

Consequences of fault occurring in the turbo pressure control system:

• Turbo pressure control is deactivated, the turbo pressure actuators operate with fixed pulse duty factors.
  
• Exhaust gas recirculation is deactivated
  
• In the event of a control deviation in the turbo pressure, the injection volume is limited and a substitute value is output for the turbo pressure.
  

Turbo pressure control is also deactivated when following faults occur:

• Fault in the exhaust-gas recirculation
  
• Fault on the turbo pressure sensor
  
• Fault on the crankshaft speed sensor
  
• Fault on the accelerator sensors
  
• Fault on the air-mass sensors
  
• Fault at terminal 15
  
• Fault on the flow regulating valve
  
• Fault on the equalization controller