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Vehicle Speed Parameters
Soft Vehicle Speed Limit
Description:
Both Vehicle Speed Limiting (VSL) and Soft Vehicle
Speed Limiting (Soft VSL) set the maximum speed of
the truck. Vehicle Speed Limiting cuts off the fuel to the
injectors when the truck exceeds the VSL programmed
mile per hour value. When you choose Soft VSL, fuel
delivery is modulated when VSL is reached. When the
truck reaches the programmed VSL value, the fuel is not
abruptly cut off. Instead, it is gradually reduced. Soft VSL
may allow the truck to exceed VSL by a maximum of 2.5
MPH (4 km/h), when the truck is using less than 50% of
the available engine horsepower.
100%
Vehicle Speed MPH (km/h)
0
Available
HP
VSL
5 MPH
(8 km/h)
No
Yes
Soft VSL
Available:
All electronically controlled on-highway engines
covered in this handbook
Range:
Range
Cat
Default
N o
Yes
No
Advantages:
Using Soft VSL feature not only allows you to “gear
fast – run slow” to optimize a balance between fuel
economy and performance or simply specify for the best
fuel economy, but also allows the driver to “run at hills”
by “warming” the turbo at the bottom of the hill. This
means that there is enough fuel to keep moderate boost
levels even though fuel delivery is tapered off by Soft
VSL.