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1998 Astro
1998 Product Information Guide 9
INJECTION (SFI) (contd.)
• A mass airflow meter constantly measures
the engine’s air requirements under
varying conditions, such as changes in
load, altitude and temperature. In an SFI
system, the mass airflow meter is essential
for accurate fuel delivery.
• The injector nozzle’s design and optimum
location produce an effective spray pattern
that contributes to the engine’s smooth
idle and impressive fuel efficiency.
TRANSMISSION
4L60-E 4-Speed Electronic
Automatic Transmission
GM’s 4L60-E 4-speed automatic Overdrive
transmission is standard equipment on
Astro. The 4L60-E’s “intelligent” electronic
controls allow the transmission to match the
engine’s performance, delivering outstanding
fuel efficiency.
• New is a two-piece transmission case
that reduces vibration and noise.
• A new, electronically controlled torque
converter clutch helps improve operating
efficiency and driveability.
• A deeper transmission oil pan
improves overall transmission
durability and fluid life.
• The 4L60-E’s wide range of gear ratios
enhances both performance and fuel
economy. The 3.06:1 first-gear ratio
provides high torque multiplication for
initial acceleration. The Overdrive 0.70:1
fourth gear lowers engine rpm at highway
speeds, providing enhanced fuel
economy and minimizing wear.
• The 4L60-E features electronic controls
designed to provide precision and
flexibility. The Powertrain Control
Module (PCM) measures key vehicle
input, including throttle position, vehicle
speed, gear range, temperature and engine
load. Four solenoids that are connected to
the PCM control shift points and shift
smoothness.
• The PCM acts as an interface between the
engine and transmission to provide the
feel of a virtually “seamless” powertrain.
• Shift timing is controlled electronically by
signals sent to the valve body’s shift
solenoids, which activate the shift valves
and execute the gear changes.
• A brake/transmission shift interlock is
standard on Astro. The interlock requires
the driver to apply the brake pedal to shift
out of Park.
• A second-gear start feature provides an
extra measure of control in hazardous
driving conditions. The driver can reduce
torque to the drive wheels by moving the
gear selector to the Drive 2 position,
thereby increasing control during initial
acceleration on slippery surfaces.
• 4L60-E is factory-filled with long-life
automatic transmission fluid will not
need to be replaced for at least 100,000
miles under normal operating conditions*
*Maintenance needs vary with different uses and driving
conditions. See owner’s manual for more information.
ABS — Unlearning Old
Habits
Buying a vehicle with
anti-lock brakes may require
drivers, unfamiliar with this
feature, to “unlearn” past
braking habits. Drivers,
accustomed to traditional
brake systems, have been
taught to “pump” the brake
pedal when braking hard on
slippery surfaces to keep the
car’s wheels from locking up.
With ABS, the system was
designed to “pump” the
brakes faster than is manually
possible, automatically adjust-
ing the brake pressure to the
wheels independently to avoid
wheel lockup. All the driver has
to do is keep firm pressure on
the brake pedal. To become
familiar with the system, dri-
vers should take the vehicle to
an unoccupied parking lot
(preferably one with slick
pavement) and practice sudden
hard-braking maneuvers to get
a feel for the system.