A non-wearing two-winding rotary actuator (ZWD 5) is fitted as the central idle speed actuator for the S62 with MSS52. It is arranged in the V-space and supplies the eight cylinders with the necessary air when idling.
Each of the eight throttle bodies features its own idle speed air duct for its cylinder. The four ducts of one cylinder bank are connected by means of three pipes with O-ring seal between the throttle bodies on the V-space side. The middle pipe between throttle body 2 and 3 (bank 1) and throttle body 6 and 7 (bank 2) is designed as a T-piece. The idle air for the corresponding cylinder bank is introduced at this point. The air is routed via a hose assembly from the idle speed actuator to the two T-pieces.
The idle speed actuator is now responsible for several tasks and is therefore an important component in the intake air tract of the engine.
Small air leaks which may occur, for example, at leaking gaiters/cylinders or in the event of a varying gap in the throttle valves can be compensated up to a certain extent by the idle speed actuator.
The idle speed actuator opens a little more during the engine coasting phase and closes just before reaching idle speed. This prevents a high vacuum in the intake pipe and oil vapours being drawn in via the valve stem seals (blue smoke).
If a fault occurs in the idle actuator during operation a corresponding fault code will be entered in the fault code memory of the DME control unit. The idle speed actuator will remain in the emergency operation position if it can no longer be activated electrically. As part of the emergency program, engine operation is upheld by this gap.