2008 JEEP GRAND CHEROKEE Owners Manual

5.7L Engines (If Equipped)
The 5.7L engine is designed to meet all
emissions regulations and provide satisfac-
tory fuel economy and performance when
using high quality unleaded gasoline hav-
ing an octane range of 87 to 89. The manu-
facturer recommends the use of 89 octane
for optimum performance. The use of premium gasoline
is not recommended. Under normal conditions, the use of
premium gasoline will not provide a benefit over high
quality regular and mid-grade gasolines, and in some
circumstances may result in poorer performance.
Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and immediate service is
required.Poor quality gasoline can cause problems such as hard
starting, stalling and hesitations. If you experience these
symptoms, try another brand of gasoline before consid-
ering service for the vehicle.
Over 40 auto manufacturer's world wide have issued and
endorsed consistent gasoline specifications (the World-
wide Fuel Charter, WWFC) to define fuel properties
necessary to deliver enhanced emissions, performance,
and durability for your vehicle. The manufacturer recom-
mends the use of gasoline that meets the WWFC speci-
fications if they are available.
Reformulated Gasoline
Many areas of the country require the use of cleaner
burning gasoline referred to as ªReformulated Gasoline.º
Reformulated gasoline contains oxygenates, and are spe-
cifically blended to reduce vehicle emissions and im-
prove air quality.
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The manufacturer supports the use of reformulated gaso-
line. Properly blended reformulated gasoline will pro-
vide excellent performance and durability of engine and
fuel system components.
Gasoline/Oxygenate Blends
Some fuel suppliers blend unleaded gasoline with oxy-
genates such as 10% ethanol, MTBE, and ETBE. Oxygen-
ates are required in some areas of the country during the
winter months to reduce carbon monoxide emissions.
Fuels blended with these oxygenates may be used in
your vehicle.
CAUTION!
DO NOT use gasoline containing Methanol or E85
Ethanol. Use of these blends may result in starting
and driveability problems and may damage critical
fuel system components.Problems that result from using methanol/gasoline
blends are not the responsibility of the manufacturer.
While MTBE is an oxygenate made from Methanol, it
does not have the negative effects of Methanol.
MMT In Gasoline
MMT is a manganese containing metallic additive that is
blended into some gasoline to increase octane. Gasoline
blended with MMT provides no performance advantage
beyond gasoline of the same octane number without
MMT. Gasoline blended with MMT reduces spark plug
life and reduces emission system performance in some
vehicles. The manufacturer recommends that gasoline
without MMT be used in your vehicle. The MMT content
of gasoline may not be indicated on the gasoline pump,
therefore, you should ask your gasoline retailer whether
or not his/her gasoline contains MMT.
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It is even more important to look for gasolines without
MMT in Canada, because MMT can be used at levels
higher than those allowed in the United States.
MMT is prohibited in Federal and California reformu-
lated gasoline.
Materials Added To Fuel
All gasoline sold in the United States is required to
contain effective detergent additives. Use of additional
detergents or other additives is not needed under normal
conditions and would result in additional cost. Therefore
you should not have to add anything to the fuel.
Fuel System Cautions
CAUTION!
Follow these guidelines to maintain your vehicle's
performance:
²The use of leaded gas is prohibited by Federal law.
Using leaded gasoline can impair engine performance,
damage the emission control system.
²An out-of-tune engine, or certain fuel or ignition
malfunctions, can cause the catalytic converter to
overheat. If you notice a pungent burning odor or
some light smoke, your engine may be out of tune or
malfunctioning and may require immediate service.
Contact your dealer for service assistance.
²The use of fuel additives which are now being sold as
octane enhancers is not recommended. Most of these
products contain high concentrations of methanol.
Fuel system damage or vehicle performance problems
resulting from the use of such fuels or additives is not
the responsibility of the manufacturer.
NOTE:Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
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Carbon Monoxide Warnings
WARNING!
Carbon monoxide (CO) in exhaust gases is deadly.
Follow the precautions below to prevent carbon
monoxide poisoning:
²Do not inhale exhaust gases. They contain carbon
monoxide, a colorless and odorless gas which can kill.
Never run the engine in a closed area, such as a
garage, and never sit in a parked vehicle with the
engine running for an extended period. If the vehicle is
stopped in an open area with the engine running for
more than a short period, adjust the ventilation system
to force fresh, outside air into the vehicle.
²Guard against carbon monoxide with proper mainte-
nance. Have the exhaust system inspected every timethe vehicle is raised. Have any abnormal conditions
repaired promptly. Until repaired, drive with all side
windows fully open.
²Keep the liftgate closed when driving your vehicle to
prevent carbon monoxide and other poisonous ex-
haust gases from entering the vehicle.
FLEXIBLE FUEL (4.7L ENGINE ONLY) Ð IF
EQUIPPED
E-85 General Information
The information in this section is for Flexible Fuel ve-
hicles only. These vehicles can be identified by a unique,
yellow fuel filler cap (gas cap) that statesEthanol (E-85)/
Unleaded Gasoline,and by theFLEXFUELbadge that
will be located on the body of your vehicle. This section
only covers those subjects that are unique to these
vehicles. Please refer to the other sections of this manual
for information on features that are common between
Flexible Fuel and gasoline only powered vehicles.
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CAUTION!
Only vehicles with the E-85 fuel filler cap (gas cap)
can operate on E-85.
ETHANOL FUEL (E-85)
E-85 is a mixture of approximately 85% fuel ethanol and
15% unleaded gasoline.
E-85 Fuel CapE-85 Badge
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WARNING!
Ethanol vapors are extremely flammable and could
cause serious personal injury. Never have any smok-
ing materials lit in or near the vehicle when remov-
ing the fuel filler tube cap (gas cap) or filling the
tank. Do not use E-85 as a cleaning agent and never
use it near an open flame.
Fuel Requirements
Your vehicle will operate on both unleaded gasoline with
an octane rating of 87, or E-85 fuel, or any mixture of
these two.For best results, a refueling pattern that alternates be-
tween E-85 and unleaded gasoline should be avoided.
When you do switch fuels, it is recommended that
²you do not switch when the fuel gauge indicates less
than 1/4 full
²you do not add less than 5 gallons when refueling
²you operate the vehicle immediately after refueling for
a period of at least 5 minutes
Observing these precautions will avoid possible hard
starting and/or significant deterioration in drivability
during warm up.
NOTE:When the ambient temperature is above 90ÉF
(32ÉC), you may experience hard starting and rough idle
following start up even if the above recommendations are
followed.
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Selection Of Engine Oil For Flexible Fuel Vehicles
(E-85) and Gasoline Vehicles
Whether operating the vehicle on an E-85 ethanol fuel or
unleaded gasoline the engine oil requirements are the
same. Refer to ªMaintenance Proceduresº in Section 7 of
this manual for the proper quality and viscosity engine
oil.
Starting
The characteristics of E-85 fuel make it unsuitable for use
when ambient temperatures fall below 0ÉF (-18ÉC). In the
range of 0ÉF (-18ÉC) to 32ÉF (0ÉC), you may experience an
increase in the time it takes for your engine to start, and
a deterioration in drivability (sags and/or hesitations)
until the engine is fully warmed up.
Cruising Range
Because E-85 fuel contains less energy per gallon than
gasoline, you will experience an increase in fuel con-
sumption. You can expect your MPG and your driving
range to decrease by about 30% compared to gasoline
operation.
Replacement Parts
Many components in your Flexible Fuel Vehicle (FFV) are
designed to be compatible with ethanol. Always be sure
that your vehicle is serviced with correct ethanol com-
patible parts.
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CAUTION!
²Replacing fuel system components with non-
ethanol compatible components can damage your
vehicle.
²Do not use ethanol mixture greater than 85% in
your vehicle. It will cause difficulty in cold start-
ing and may affect drivability.
FUEL REQUIREMENTS (DIESEL ENGINES)
Use good quality diesel fuel from a reputable supplier.
For most year-round service, No. 2 diesel fuel meeting
ASTM specification D-975 Grade S15 will provide good
performance. If the vehicle is exposed to extreme cold
(below 20É F or -7É C), or is required to operate at
colder-than-normal conditions for prolonged periods,
use climatized No. 2 diesel fuel or dilute the No. 2 dieselfuel with 50% No. 1 diesel fuel. This will provide better
protection from fuel gelling or wax-plugging of the fuel
filters.
This vehicle is fully compatible with biodiesel blends
up to 5% biodiesel meeting ASTM specification D-975.
NOTE: Federal law requires that you must fuel this
vehicle with Ultra Low Sulfur Highway Diesel fuel (15
ppm Sulfur maximum) and prohibits the use of Low
Sulfur Highway Diesel fuel (500 ppm Sulfur maxi-
mum) to avoid damage to the emissions control system.
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