Electrical throttle valves in the S54 engine

Many high-performance engines have individual throttle valves. In the S54 engine, these are arranged around a separate throttle body shaft. The individual throttle valves are operated by an electric positioning motor without a direct mechanical link to the accelerator pedal.

Tasks of electric throttle valve (EDK)

The electric throttle valve fulfils following tasks:

- Implementing the driver's load choice

- Vehicle speed control

- Intervention by the vehicle handling control systems

- Emergency operation

- Load application (e.e.: seat heating, air conditioning system, lights)

- Maximum speed limitation

Structure and function of the EDK and potentiometers

The electric throttle valve (EDK) is operated by DC motor via a gearing system. The adjustment positions are sensed by means of potentiometers. The first potentiometer is a discreet component, whereas the second potentiometer is connected to the ”electric throttle-valve actuator” unit.

The electric throttle-valve actuator is activated by the engine management system with a pulse-width modulated signal.

Troubleshooting

The following monitoring functions are processed in the two test modules ”electric throttle valves” and ”electric throttle valve potentiometers”:

• Control units internal fault: throttle valve
  
• Throttle-valve faults, general
  
• Fault in throttle-valve adaptation or start check
  
• Function of both throttle valve potentiometers defective (general, signals implausible, plausibility with regard to air mass)
  
• Throttle valve actuator is sluggish or jams (temporarily or permanently)
  
• Activation of throttle-valve actuator defective
  

Replacement of EDK and idle synchronisation

If the EDK is replaced on a vehicle, the throttle valve stops must be reset. The precise procedure is explained in the repair instruction. On completion of the mechanical adjustments, idling speed synchronisation must be carried out. To do so, run the service function <Idle speed correction>.