Auxiliary Throttle Valve Control (ADS 11)

PURPOSE
The Auxiliary Throttle Valve Control (ADS II) system allows Automatic Stability Control (ASC) and Engine Drag Torque control (MSR) regulation in the event of excessive wheel slip during acceleration or engine braking.





ADS 11 Components:
- ADS 11 Choke-Valve Plate assembly (auxiliary throttle valve) which is normally held open by spring pressure, mounted upstream of the throttle body.





- ADS II Actuator which closes the choke-valve plate by action of a bowden cable.

ADS 11 Control Module Location:

- ADS II Control Module which controls the ADS II actuator.

ADS 11 Operation:

OPERATION
Normal Throttle Operation
During non-slip Control operation engine power output is controlled by a manually operated throttle body. This primary throttle body is controlled by a standard accelerator pedal and bowden cable.

ADS 11 Operation:

Acceleration Slip Control (ASC+T)
When the Slip Control Module (ASC+T) detects excessive wheel slip due to acceleration, it signals the ADS II control module via a pulse-width modulated signal as to the necessary amount of power reduction required. The ADS 11 control module then activates the ADS II actuator. Via a bowden cable (similar to cruise control actuator operation), the ADS II actuator closes the choke valve plate and thereby reduces engine power. If additional regulation is required, the ASC+T control module can also signal the Digital Motor Electronic (DME) module, which can then retard ignition timing to further reduce engine power. Further traction control at the rear wheels can be achieved via brake application by the ASC+T hydraulic unit.

ADS 11 Operation:

Deceleration Slip Control (MSR)
When the ASC+T module detects excessive wheel slip due to engine braking (drag torque), it signals the DME control module which now opens the Idle Speed Control Valve (ZWD 5) slightly to reduce engine drag torque and the ADS 11 Actuator remains idle (auxiliary throttle plate open). Further engine drag torque reduction is also obtained by the DME control module advancing the ignition timing and canceling the deceleration fuel cut-off function.