## Fuel and Emissions Systems

#### System Descriptions (cont'd)

11-33

Variable Swirl System (VSS)

The inlet passage shut-off is a pure open loop control. Depending on the air temperature the shut-off can be switched on and off by a hysteresis. If the air temperature falls below the threshold or a flame start command is activated depending on the switches the flap is controlled with the on/off ration. If the air temperature exceeds the threshold, the on/off ratio is calculated again.

The setpoint value for the flap is calculated from a map depending on engine speed and the sum of demand and low-idle quantity, which have been corrected using the curve depending on the atmospheric pressure.

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