Swirl flap control DDE 5.0

The adjustable swirl flaps are located in the tangential channels of the intake system and are opened and closed according to the operating status of the engine. The swirl flaps are closed under the following conditions:

• at low engine speeds and low injection volumes (map-controlled)
  

The swirl flaps generally remain open when

• the coolant temperature < 15°C OR
  
• the intake air temperature < 15°C
  

Function

The pressure converter connects the vacuum unit with the vacuum supply by means of hoses. When activated by the DDE control unit, the changeover valve switches vacuum to the vacuum unit. The vacuum unit actuates the control rod and the swirl flaps close. The control rod is up against the rear stop when the swirl flaps are open.

Troubleshooting

If a fault is detected in the control of the pressure converter, the following faults may be detected:

• 4130, Activation short circuit to B+
  
• 4141, Activation short circuit to B-
  
• 4152, Activation circuit break
  
• 4153, Excess temperature output stage
  

Effects of faults

If the swirl flaps stick in open position: Deterioration in exhaust gas characteristics in lower speed ranges otherwise no effect.

If the swirl flaps stick in closed position: Power loss of approx. 10% at higher engine speeds.