DDEC VI ENGINE DRIVING TIPS
In general, when using a 7 or 9-speed
transmission, you should always
downshift between 1250 and 1300
rpm. This is true even on steep grades
with heavy loads. When using an 18-,
15- or 13-speed transmission, you
will need to downshift at an rpm that
allows “less than rated” rpm before
throttle application in the next gear
down. You may want to limit engine
speed to 1900 rpm in all gears.
Low rpm operation should feel greatly
enhanced due to the characteristics
of the variable nozzle turbocharger.
Engine response should be almost
instantaneous below peak torque
engine speeds. This should encourage
progressive shifting especially during
slow vehicle speed operation.
One difference you may notice with
the EGR equipped engine is under
hood noise. The gear train has been
redesigned for quieter operation,
and the EGR gas
fl
ow may be
noticeable to the tuned attentive ear.
The turbocharger operates at higher
boost pressure forcing EGR gas
fl
ow
through the EGR plumbing. In some
situations the driver may believe
he/she has experienced a charge air
cooler system leak. Even connecting
trailer light and air hoses, the driver
may hear a different tone (exhaust and
under hood with the engine idling.) If
equipped with a turbo boost gage, the
driver may occasionally note intake
manifold pressure exceeds 35 psi.
Idling
The common belief that idling a diesel
engine causes no engine damage is
wrong. Idling produces sulfuric acid,
which breaks down the oil and eats
into bearings, rings, valve stems and
engine surfaces. If you must idle
the engine for cab heat or cooling,
the
high idle
function of the Cruise
Control switches should be used. An
idle speed of 1100 rpm should be
enough to provide cab heat in above
0° C (32° F) ambients.
54
All information subject to change without notice.
(Rev. 04/08)
DDC-SVC-MAN-0040 0704
Copyright © 2008 DETROIT DIESEL CORPORATION
Summary of Contents for MBE 900
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