Jeep Cherokee 2000 Service Manual - page 358
any/all spark plug(s), refer to Ignition Coil-4.0L
Engine Removal/Installation.
(1) 2.5L 4–Cylinder Engine: Always remove spark
plug or ignition coil cables by grasping at the cable
boot (Fig. 18). Turn the cable boot 1/2 turn and pull
straight back in a steady motion. Never pull directly
on the cable. Internal damage to cable will result.
(2) Prior to removing the spark plug, spray com-
pressed air around the spark plug hole and the area
around the spark plug. This will help prevent foreign
material from entering the combustion chamber.
(3) Remove the spark plug using a quality socket
with a rubber or foam insert.
(4) Inspect the spark plug condition. Refer to
Spark Plugs Conditions.
PLUG CLEANING
The plugs may be cleaned using commercially
available spark plug cleaning equipment. After clean-
ing, file the center electrode flat with a small point
file or jewelers file before adjusting gap.
CAUTION: Never use a motorized wire wheel brush
to clean the spark plugs. Metallic deposits will
remain on the spark plug insulator and will cause
plug misfire.
PLUG GAP ADJUSTMENT
Check the spark plug gap with a gap gauge tool. If
the gap is not correct, adjust it by bending the
ground electrode (Fig. 19). Never attempt to adjust
the gap by bending the center electrode.
SPARK PLUG GAP
•
2.5L 4-Cylinder Engine Spark Plug Gap:.89 mm
(.035 in).
•
4.0L 6-Cylinder Engine Spark Plug Gap:.89 mm
(.035 in).
PLUG INSTALLATION
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion. This may result
in a change in the spark plug gap, or a cracked por-
celain insulator.
When replacing the spark plug and ignition coil
cables, route the cables correctly and secure them in
the appropriate retainers. Failure to route the cables
properly can cause the radio to reproduce ignition
noise. It could cause cross ignition of the spark plugs,
or short circuit the cables to ground.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.
(2) Tighten the spark plugs to 35-41 N·m (26-30 ft.
lbs.) torque.
(3) 2.5L 4–Cylinder Engine: Install spark plug
cables over spark plugs.
(4) 4.0L 6–Cylinder Engine: Install coil rail. Refer
to Ignition Coil-4.0L Engine Removal/Installation.
Fig. 18 Cable Removal
1 – SPARK PLUG CABLE AND BOOT
2 – SPARK PLUG BOOT PULLER
3 – TWIST AND PULL
4 – SPARK PLUG
Fig. 19 Setting Spark Plug Gap—Typical
1 – GAUGE
2 – SPARK PLUG
XJ
IGNITION SYSTEM
8D - 11
REMOVAL AND INSTALLATION (Continued)