Engine Start and Operation
263
Uphill Operation
For best performance, allow engine speed
to reach the bottom of the rated torque
range before downshifting. Continue to
downshift in this manner until a gear is
reached that will maintain the desired
speed. Continue to operate at the rated
torque if the vehicle will make it to the top
without a downshift. Begin upshifting as
the grade of the hill decreases and the en-
gine begins to accelerate above 1600 r/min.
Driving this way will give the best fuel
economy and performance.
NOTE!
Allowing the engine to lug down
to the end of maximum torque range is per-
missible if the vehicle is cresting the top of
a hill. However, extended operation at en-
gine speeds below the maximum torque
range (usually 1100 to 1200 r/min) will
raise exhaust temperature and cylinder pres-
sure. This can lead to reduced engine life.
Downhill Operation
CAUTION
Do not exceed engine manufacturer’s
recommended maximum engine speed.
Engine damage can occur. If equipped
with an engine or exhaust brake, do not
exceed 2300 r/min.
On a downgrade, do not coast with the
clutch pedal depressed or the transmission
in neutral. Select a gear that does not allow
the engine speed to exceed the engine
manufacturer’s maximum engine speed rec-
ommendation. Use the engine or exhaust
brake and/or the service brakes to control
the vehicle speed. A simple rule is to select
the same gear used to go up the grade.
