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Swirl throttle

Swirl throttle





The swirl throttle closes the tumble passage at light loads so that all the air must pass through the swirl passage. Thereby, a higher air velocity and better filling factor in the cylinder can be attained. When the engine speed and thereby the amount of air increases, the throttle will open the tumble passage so that the amount of air required by the engine is made available.

The timing ratio for the swirl throttle is looked up in a table based on the engine speed and the injected fuel quantity. It is then passed on to the final stage control, where the signal is amplified and compensated for the battery voltage, see the table.

Voltage (V)

Compensation value

9

1.4

14.2

1.0

16

0.775



The value in the table is multiplied with the current timing ratio. This is done to compensate for a higher or lower voltage than 14.2 V resulting in a different valve lift and consequently an incorrect control of the valve.

The timing ratio is then available on the control module pin to be connected to the swirl throttle control valve.

Diagnostics

When the swirl throttle function generates a DTC:


• CHECK ENGINE

• Somewhat lower performance