2006 JEEP GRAND CHEROKEE engine

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.
It is even more important to look for gasoline without
MMT in Canada because MMT can be used at levels
higher than allowed in the United States. MMT is pro-
hibited in Federal and California reformulated 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.
Fuel System Cautions
CAUTION!
Follow these guidelines to maintain your vehicle’s
performance:
•The use of leaded gas is prohibited by Federal law.
Using leaded gasoline can impair engine performance,
damage the emission control system.
304 STARTING AND OPERATING

•An 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.
•The 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.
Carbon Monoxide Warnings
WARNING!
Carbon monoxide (CO) in exhaust gases is deadly.
Follow the precautions below to prevent carbon
monoxide poisoning:
•Do 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.
STARTING AND OPERATING 305
5

CAUTION!
Damage to the fuel system or emission control
system could result from using an improper fuel cap
(gas cap). A poorly fitting cap could let impurities
into the fuel system. Also, a poorly fitting after-
market cap can cause the MIL (Malfunction Indica-
tor Light) to illuminate, due to fuel vapors escaping
from the system.
•Turn the engine off.
•Rotate the fuel cap to the left to remove.
•To replace the cap, insert it into the filler neck and
tighten the cap about 1/4 turn until you hear one click.
This is an indication that the cap is properly tightened.
•Make sure that the fuel cap tether strap is not caught
under the fuel cap.
CAUTION!
To avoid fuel spillage and overfilling, do not“top
off”the fuel tank after filling.
NOTE:When the fuel nozzle“clicks”or shuts off, the
fuel tank is full.
Loose Fuel Filler Cap Message
If the vehicle diagnostic system determines that the fuel
filler cap is loose, improperly installed, or damaged, a
“CHECK GAS CAP”message will be displayed in the
EVIC (Electronic Vehicle Information Center). Refer to
“Electronic Vehicle Information Center”in Section 4 of this
manual. Tighten the fuel filler cap properly and press the
odometer reset button to turn the message off. If the
problem continues, the message will appear the next time
the vehicle is started. Refer to“Onboard Diagnostic System
—OBDII”in Section 7 of this manual for more information.
STARTING AND OPERATING 307
5

WARNING!
•Remove the fuel cap (gas cap) slowly to prevent
fuel spray from the filler neck which may cause
injury.
•The volatility of some gasoline may cause a
buildup of pressure in the fuel tank that may
increase while you drive. This pressure can result
in a spray of gasoline and/or vapors when the cap
is removed from a hot vehicle. Removing the cap
slowly allows the pressure to vent and prevents
fuel spray.
•Never have any smoking materials lit in or near
the vehicle when the fuel cap is removed or the
tank filled.
•Never add fuel to the vehicle when the engine is
running.
WARNING!
A fire may result if gasoline is pumped into a
portable container that is inside of a vehicle. You
could be burned. Always place gas containers on the
ground while filling.
TRAILER TOWING
In this section you will find safety tips and information
on limits to the type of towing you can reasonably do
with your vehicle. Before towing a trailer carefully re-
view this information to tow your load as efficiently and
safely as possible.
To maintain warranty coverage, follow the requirements
and recommendations in this manual concerning ve-
hicles used for trailer towing.
308 STARTING AND OPERATING

Trailer Towing Weights (Maximum Trailer Weight
Ratings)
The following chart provides the maximum trailer
weight ratings towable for your given drivetrain.
Engine/
Transmis-
sionModel GVWR (Gross
Vehicle Wt. Rat-
ing)GCWR (Gross
Combined Wt.
Rating)Frontal Area Max. GTW
(Gross Trailer
Wt.)Max. Tongue
Wt. (See Note
1)
3.7L/
Automatic4x2 5,700 lbs (2 585
kg)8,000 lbs (3 629
kg)40 Sq. Ft. (3.72
square meters)3,500 lbs (1 587
kg)350 lbs (159
kg)
3.7L/
Automatic4x4 5,900 lbs (2 676
kg)8,200 lbs (3 719
kg)40 Sq. Ft. (3.72
square meters)3,500 lbs (1 587
kg)350 lbs (159
kg)
4.7L/
Automatic4x2 5, 850 lbs (2 653
kg)11,200 lbs (5 080
kg)60 Sq. Ft. (5.57
square meters)6,500 lbs (2 948
kg)650 lbs (295
kg)
4.7L/
Automatic4x4 6,100 lbs (2 767
kg)11,450 lbs (5 194
kg)60 Sq. Ft. (5.57
square meters)6,500 lbs (2 948
kg)650 lbs (295
kg)
5.7L/
Automatic4x4 6,150 lbs (2 789
kg)12,200 lbs (5 534
kg)60 Sq. Ft. (5.57
square meters)7,200 lbs (3 266
kg)720 lbs (327
kg)
Refer to local laws for maximum trailer towing speeds.
312 STARTING AND OPERATING

WARNING!
Improper towing can lead to an injury accident.
Follow these guidelines to make your trailer towing
as safe as possible:
Make certain that the load is secured in the trailer
and will not shift during travel. When trailering
cargo that is not fully secured, dynamic load shifts
can occur that may be difficult for the driver to
control. You could lose control of your vehicle and
have an accident.
•When hauling cargo or towing a trailer, do not over-
load your vehicle or trailer. Overloading can cause a
loss of control, poor performance or damage to brakes,
axle, engine, transmission, steering, suspension, chas-
sis structure or tires.
•Safety chains must always be used between your
vehicle and trailer. Always connect the chains to the
frame or hook retainers of the vehicle hitch. Cross the
chains under the trailer tongue and allow enough
slack for turning corners.
•Vehicles with trailers should not be parked on a grade.
When parking, apply the parking brake on the tow
vehicle. Put the tow vehicle automatic transmission in
P for Park. With a manual transmission, shift the
transmission into reverse. And with four-wheel-drive
vehicles, make sure the transfer case is not in neutral.
Always, block orchockthe trailer wheels.
•GCWR must not be exceeded.
•Total weight must be distributed between the tow
vehicle and the trailer such that the following four
ratings are not exceeded:
1. GVWR
STARTING AND OPERATING 315
5

If using a manual transmission vehicle for trailer towing,
all starts must be in FIRST gear to avoid excessive clutch
slippage.
Towing Tips—Automatic Transmission
The“D”range can be selected when towing. However, if
frequent shifting occurs while in this range, the”Tow/
Haul”mode (if equipped) or the“3”range should be
selected. Shift the transmission to Drive position 2 on
more severe grades.
NOTE:Using the”Tow/Haul”mode (if equipped) or
the“3”range while operating the vehicle under heavy
operating conditions will improve performance and ex-
tend transmission life by reducing excessive shifting and
heat build up. This action will also provide better engine
braking.The automatic transmission fluid and filter should be
changed if you REGULARLY tow a trailer for more than
45 minutes of continuous operation. See Schedule“B”in
section 8 of this manual for transmission fluid change
intervals.
NOTE:Check the automatic transmission fluid level
before towing.
Towing Tips—Electronic Speed Control (If
Equipped)

Don’t use in hilly terrain or with heavy loads.
When using the speed control, if you experience speed
drops greater than 10 mph (16 km/h), disengage until
you can get back to cruising speed.
Use speed control in flat terrain and with light loads to
maximize fuel efficiency.
STARTING AND OPERATING 319
5

Towing Tips—Cooling System
To reduce potential for engine and transmission over-
heating, take the following actions:
City Driving
When stopped for short periods of time, put transmission
in neutral and increase engine idle speed.
Highway Driving
Reduce speed.
Air Conditioning
Turn off temporarily.
refer to Cooling System Operating information in the
Maintenance section of this manual for more informa-
tion.
RECREATIONAL TOWING (BEHIND
MOTORHOME, ETC.)
Towing–2WD Models
Recreational towing is allowed ONLY if the driveshaft
is removed.Towing with the rear wheels on the ground
while the driveshaft is connected can result in severe
transmission damage.
Towing—Quadra-Trac I (Single-Speed Transfer
Case) 4WD Models
Recreational towing is not allowed.This model does not
have a N (Neutral) position in the transfer case.
320 STARTING AND OPERATING