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Powertrain
“Explorer’s powertrains are among the most sophisticated in
any SUV. The new all-aluminum V-8 delivers more power, more
efficiently, while the improved V-6 is more refined. Combined with
two new transmissions and a rugged, updated 4×4 system, Explorer’s
powertrains deliver everything from improved all-around performance
to more serious trailer towing capabilities.”
– Steve von
Foerster, Explorer Chief Program Engineer
- New all-aluminum 4.6-liter SOHC V-8 delivers 240 horsepower
and provides impressive low-end and mid-range torque
- New maintenance-free, wide-ratio 5-speed automatic transmission
gives customers improved city and highway merging performance and
better NVH
- Refined 5-speed manual transmission (for the V-6) delivers
car-like shift quality in a robust truck powertrain
- New high-tech electronic engine controls integrate several
electronic boxes for better reliability
- Improved 210 horsepower 4.0-liter SOHC V-6 is now standard and
features an all-new composite plastic intake system for improved
sound quality and better durability
- Improved Control Trac four-wheel-drive system
With a new all-aluminum V-8 engine, improved V-6, improved manual
and automatic transmissions, sophisticated new electronic engine
controls and refined Control Trac four-wheel-drive system, the
new Ford Explorer has even more power to fulfill its mission as the
most refined, practical, hardworking and versatile SUV.
Explorer offers customers a choice of two engines. The standard
engine is an upgraded 4.0-liter single overhead cam (SOHC) V-6.
Also available is a new sophisticated, more powerful, lighter-weight
4.6-liter, all-aluminum, SOHC V-8. It replaces the former 5.0-liter
pushrod V-8.
4.6-liter SOHC V-8
Explorer’s 4.6-liter engine – the first all-aluminum entry in a
Ford SUV – delivers 240 horsepower at 4,750 rpm and 280 foot-pounds
of peak torque at 4,000 rpm, providing sure freeway merging. Power
is up from 215 horsepower in the former 5.0-liter V-8.
The added power and torque contribute to Explorer’s higher tow
rating for 2002.
The torque curve for the 4.6-liter V-8 exceeds 250 foot-pounds at
revs as low as 1,500 rpm, and remains above that mark all the way to
5,000. This translates into responsive around-town driving and
freeway cruising.
Besides the added power, the new V-8 also offers improved part
throttle feel, better drivability and less weight than the 5.0-liter
it replaces. Engine oil capacity is increased to 6 quarts for
better cooling and longer engine life. The engine’s reliable
coil-on-plug design eliminates conventional spark plug wires.
4.0-liter SOHC V-6
The proven aluminum-head, 4.0-liter, SOHC V-6 engine offers 210
horsepower at 5,250 rpm and 250 foot-pounds of peak torque at 4,000
rpm. The torque curve for the 4.0-liter engine is designed to be
relatively level across the entire rev range, providing strong
performance at nearly any engine speed.
An all-new, equal-length composite plastic intake system was
added for improved sound quality, while engine durability was
improved through the use of aluminum main bearings.
Explorer also offers flexible fuel capability with the standard
4.0-liter V-6 engine and automatic transmission. The Explorer
flexible fuel vehicle (FFV) can operate on gasoline or a blend of
gasoline and ethanol. The use of E85 fuel reduces carbon dioxide
emissions by as much as 20 percent, compared with gasoline.
Both engines meet Low Emissions Vehicle (LEV) standards. Fuel
economy has been held constant – even with a larger vehicle and one
that can seat two more passengers than the prior model – thanks to
several weight-saving innovations. An all-aluminum hood and V-8
engine block as well as a magnesium cross bar beam save
approximately 90 pounds.
Both engines offer exceptional reliability and will go 100,000
miles before the first scheduled tune-up under normal driving
conditions with routine fluid and filter changes.
New Automatic and Manual Transmissions
Explorer features manual and automatic transmissions. Both offer
improved operation and greater efficiency than the units they
replace.
The new wide-ratio, 5-speed, 5R55W5 automatic provides improved
performance over most four- and five-speed transmissions. It is
internally balanced for better NVH.
The transmission team’s goals were to improve launch
acceleration, quiet operation and reduce customer service needs. A
major step in that direction comes from Explorer’s new 44-pound
single aluminum transmission casting. The single casting greatly
reduces NVH and powertrain bending at higher speeds.
The transmission carries more torque through its new wide-ratio
five-speed. First gear now has a ratio of 3.26 compared with 2.47
for the previous transmission. Similar gains were made through the
other four gears, giving the Explorer improved city and highway
merging performance.
To reduce noise, Ford developed a quieter oil pump and new
planetary gear designs. Planetary gears provide different ratios as
a transmission goes through shifts.
Another major change is in what cannot be found under the hood –
a dipstick. The new transmission is sealed at the factory with 11
quarts of a semi-synthetic blend of specially formulated fluid that
should not require service for 150,000 miles. This is a benefit to
owner convenience and the environment.
Because Explorer is the first Ford SUV with a sealed
transmission, it was subjected to a series of brutal lab and
real-world tests. Some tests were conducted in Ford’s Research and
Engineering Center in Dearborn, Mich., where the transmission was
run for 50,000 miles at speeds of 115-120 mph on a dynamometer.
Real-world tests took place at Ford’s Arizona Proving Grounds,
where trailer pulling, mud baths and steep hill-climbs were standard
daily fare.
Later in 2001, Explorer’s five-speed manual transmission will be
available on the 4.0-liter V-6. It has increased torque capacity to
handle the engine’s higher output, new offset-chamfer design
synchronizers and an all-new hydraulic clutch system with improved
clutch disk. The goal was car-like shift quality in a robust truck
powertrain.
A 3.27 axle ratio is standard for all automatic 4×2 XLS and XLT
models. A 3.55 axle ratio is standard on 4×4 manual XLS, 4×4 XLT,
Eddie Bauer and Limited models. A 3.73 axle ratio and limited slip
differential are standard with the Class III/IV towing package.
Towing capacity is increased with Explorer’s V-8 engine. The
standard receiver hitch, which is part of the rear frame, offers
Class II towing capacity of 3,500 pounds, depending on engine and
drivetrain. An upgraded towing package, which includes a limited
slip rear differential, provides Class III/IV towing capability of
up to 7,300 pounds. A built-in hitch receiver offers towing
capability right from the factory and can accept many accessories,
such as a bicycle rack.
New Electronic Engine Controls
A next-generation 32-bit Powertrain Electronic Controller (PTEC)
manages all engine and transmission functions, along with speed
control and many other powertrain functions.
“If you think of the previous-generation electronic engine
control module as a 286 computer, the new PTEC is like a Pentium,”
explains Mike Pruitt, powertrain program planner. “It’s very
powerful.”
The new PTEC module integrates several electronics boxes, for
better reliability.
The electronic controller is so sophisticated that it raised
national security issues during development.
Because it uses a high-tech internal code, the United States
government at one point forbid engineers from taking it across
international borders.
The main benefit of PTEC is that it allowed engineers to more
precisely control engine functions – including combustion – under a
broader variety of operating conditions. The result is better
emissions control, reliability and efficiency.
Ford expects to use the PTEC in a broad range of vehicles in the
future.
The PTEC module in Explorer also controls the 4.0-liter V-6’s
flexible fuel capability, allowing it to operate on environmentally
responsible gasoline-alcohol blends of up to 85 percent ethanol.
The PTEC allowed engineers to give the 4.6-liter V-8 a fail-safe
coolant strategy to prevent engine damage through overheating. When
the cylinder head temperature rises too high as a result of coolant
loss, the engine’s electronic controls shut off fuel to alternating
banks of cylinders – but continue to pump cool air through those
cylinders – to allow the driver to drive a short distance without
engine damage.
Explorer’s transmission also benefits from this “smart”
electronics approach. Adaptive pressure control technology helps
keep transmission shifts consistent over time, even as the
transmission wears.
The same adaptive technology extends to engine controls. The
powertrain control module adjusts for hundreds of variables,
including throttle position – a key indicator of how the driver
wants the engine to perform.
Improved Control Trac 4×4 Performance
Explorer’s Control Trac four-wheel-drive system has been
refined to make it more “transparent” to the driver, while improving
its abilities in limited traction situations.
For the first time, the optional, two-speed four-wheel drive
system has its own electronic controller, which can be likened to
the latest high-speed personal computer. The extra computing power
gave Explorer’s engineers the ability to fine-tune the system to a
wide variety of demands.
For example, sensors measure and compare front and rear drive
shaft speeds, as well as throttle position – to figure the driver’s
intent into the mathematical formula that determines how much torque
to send to each axle.
These measurements are taken 50 times per second, for an almost
seamless adjustment of the clutch that controls the transfer case
output in the 4×4 system’s “automatic” setting.
If the rear wheels lose traction, the optimal amount of torque
for the situation is transferred to the front – up to 500
foot-pounds.
But the system doesn’t have to wait to sense slip before it takes
action. For example, if the Explorer is sitting at rest in a
four-wheel-drive setting and the driver presses the accelerator, the
controller sends torque to both the front and back wheels within
milliseconds and then samples the results. This heads off wheel
spin in low-traction situations.
The Control Trac system includes a pushbutton switch –
versus the former rotary knob – on the instrument panel that allows
the operator to select “4×4 Auto,” “4×4 High” or “4×4 Low” modes.
In 4×4 Auto – recommended for most driving situations – the
system continuously monitors conditions and adjusts front-wheel
torque, combining transparent all-surface operation with highly
capable four-wheel drive. When in automatic mode, the Control
Trac drivetrain normally delivers all engine torque to the
rear wheels. It uses an electronically controlled electromagnetic
clutch to redirect up to 100 percent of engine torque to the front
wheels when it detects rear-wheel slippage or heavy throttle
application.
In 4×4 High – recommended for severe winter weather and off-road
conditions – the system effectively locks the front and rear
driveshafts together to provide optimal traction of four wheels.
In 4×4 Low – recommended for low-speed off-road driving or
high-torque situations, such as towing a boat out of the water – the
system locks the front and rear driveshafts together but adds a
2.48:1 gear reduction, which provides extra pulling power.
Neither 4×4 high nor 4×4 Low is recommended for dry road
operation.
An important consideration in designing the 4×4 system was to
make sure the wheels don’t “bind” during turns in the automatic
mode, providing uncomfortable feedback to the driver. Built into
the Control Trac system is a smart control. Unlike typical
mechanical 4×4 systems, Explorer’s Control Trac can even
adjust for such variables as differences in tire pressure.
By continually tailoring torque transfer before any slip is
detected, the system actually helps prevent wheels from losing
traction in the first place. The 4×4 system kicks in when needed
without telltale pulses or harshness. The Control Trac
transfer case housing is made of magnesium for reduced weight.
ControlSlip Rear Driveshaft
Four-wheel-drive Explorer models are equipped with a patented new
ControlSlip rear driveshaft, which provides exceptional stiffness,
for quiet performance.
It has safety benefits as well. In the event of a frontal
impact, the driveshaft is designed to telescope, not buckle. This
movement helps the vehicle further absorb impact forces and manage
energy. In addition, the driveshaft is thinner than the previous
shaft and contributes to a 3.5-pound weight savings.
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