HOW TO: Change Spark Plugs

REMOVAL

2.4L
If spark plug for #2 or #3 cylinder is being
removed, throttle body must be removed. Refer to
Throttle Body Removal.
(1) Remove air cleaner tube and housing.
(2) Twist secondary cable at cylinder head to break
loose at spark plug. Remove cable from plug.
(3) Prior to removing spark plug, spray compressed
air into cylinder head opening. This will help
prevent foreign material from entering combustion
chamber.
(4) Remove spark plug from cylinder head using a
quality socket with a rubber or foam insert.
(5) Inspect spark plug condition. Refer to Spark
Plug Conditions.

3.7L
Each individual spark plug is located under each
ignition coil. Each individual ignition coil must be
removed to gain access to each spark plug. Refer to
Ignition Coil Removal/Installation.
(1) Prior to removing ignition coil, spray compressed
air around coil base at cylinder head.
(2) Prior to removing spark plug, spray compressed
air into cylinder head opening. This will help
prevent foreign material from entering combustion
chamber.
(3) Remove spark plug from cylinder head using a
quality socket with a rubber or foam insert. Also
check condition of ignition coil o-ring and replace as
necessary.
(4) Inspect spark plug condition. Refer to Spark
Plug Conditions.

CLEANING SPARK PLUGS
The plugs may be cleaned using commercially
available spark plug cleaning equipment. After cleaning,
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.

INSTALLATION

2.4L
CAUTION: Spark plug tightening on the 2.4L is
torque critical. The plugs are equipped with tapered
seats. Do not exceed 15 ft. lbs. torque.
Special care should be taken when installing spark
plugs into the cylinder head spark plug wells. Be
sure the plugs do not drop into the plug wells as electrodes
can be damaged.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion resulting in a
change in the spark plug gap or a cracked porcelain
insulator.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.
(2) Tighten spark plugs. Refer to torque specifications.
(3) Install throttle body. Refer to Throttle Body
Installation.
(4) Install air cleaner tube and housing.

3.7L
Special care should be taken when installing spark
plugs into the cylinder head spark plug wells. Be
Fig. 26 Preignition Damage
1 - GROUND ELECTRODE STARTING TO DISSOLVE
2 - CENTER ELECTRODE DISSOLVED
Fig. 27 Spark Plug Overheating
1 - BLISTERED WHITE OR GRAY COLORED INSULATOR
KJ IGNITION CONTROL 8I - 15
SPARK PLUG (Continued)
sure the plugs do not drop into the plug wells as electrodes
can be damaged.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion resulting in a
change in the spark plug gap or a cracked porcelain
insulator.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.
(2) Tighten spark plugs. Refer to torque specifications.
(3) Before installing coil(s), check condition of coil
o-ring and replace as necessary. To aid in coil installation,
apply silicone to coil o-ring.
(4) Install ignition coil(s). Refer to Ignition Coil
Removal/Installation.


IGNITION COIL

DESCRIPTION

2.4L
The coil assembly consists of 2 different coils
molded together. The assembly is mounted to the top
of the engine (Fig. 14).

3.7L
The 3.7L V-6 engine uses 6 dedicated, and individually
fired coil for each spark plug (Fig. 15). Each
coil is mounted directly into the cylinder head and
onto the top of each spark plug (Fig. 16).

REMOVAL

2.4L
(1) Disconnect electrical connector at rear of coil.
(2) Remove all secondary cables from coil.
(3) Remove 4 coil mounting bolts (Fig. 17).
(4) Remove coil from vehicle.

3.7L
An individual ignition coil is used for each spark
plug (Fig. 19). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 18). The bottom
of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.
19) is used to seal the coil at the opening into the cylinder
head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector from coil by
pushing downward on release lock on top of connector
and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
(4) Remove coil mounting nut from mounting stud
(Fig. 18).
(5) Carefully pull up coil from cylinder head opening
with a slight twisting action.
(6) Remove coil from vehicle.

INSTALLATION

2.4L
(1) Position coil to engine.
(2) Install 4 mounting bolts. Refer to torque specifications.
(3) Install secondary cables.
(4) Install electrical connector at rear of coil.
(5) Install air cleaner tube and housing.

3.7L
(1) Using compressed air, blow out any dirt or contaminants
from around top of spark plug.
(2) Check condition of coil o-ring and replace as
necessary. To aid in coil installation, apply silicone to
coil o-ring.
Fig. 17 IGNITION COIL - 2.4L
1 - IGNITION COIL
2 - MOUNTING BOLTS (4)
8I - 10 IGNITION CONTROL KJ
IGNITION COIL (Continued)
(3) Position ignition coil into cylinder head opening
and push onto spark plug. Do this while guiding coil
base over mounting stud.
(4) Install coil mounting stud nut. Refer to torque
specifications.
(5) Connect electrical connector to coil by snapping
into position.
(6) If necessary, install throttle body air tube or
box.

What are good replacement plugs>?

Is it easy to get to all six plugs or do I have to remove a bunch of other stuff to get to the plugs? Is it a pretty easy job?

farwellbooth said:

What are good replacement plugs>?

Is it easy to get to all six plugs or do I have to remove a bunch of other stuff to get to the plugs? Is it a pretty easy job?

Click to expand...

I like the Iridium plugs, I plan to try them out this spring. Try this link it may help. http://www.sparkplugs.com/results_app.asp?productTypeID=1&AAIA=1386851

I did this last night using plugs from the dealer (14 bucks with tax)

10mm socket to get the bolt off to remove the ignition coils
5/8 spark plug socket for the plugs
and a screw driver to remove the air intake hose from the airbox to the throtle body.
I also found that a 10" extension and 2 3" extensions were very handy to have.

changing spark plugs....nice verbal description...

great narrative on how to change spark plugs. Are there any pictures available to make it somewhat easier????? =D>

In addition to previously mentioned suggestions, I found that 2, 6'' extensions, making 12'' was ideal to get past hoses to access the plug.
Also a 6'' extension for removal of the 10mm nuts on the coils was very helpful.

For those of you moving the coolant tank to one side to access the #6 coil and plug, when you reattach the coolant tank, stack 5 metal washers (in-between the plastic and nut) on the mounting studs, so in the future, you can use a non-deep 10mm socket to easy removal.

Also don't forget to use anti-seize compound on the new plugs.

Taking your time, about 2 hours to complete.

First time doing it, took me 1.5 hours. I found a universal joint made this job much easier... and actually possible without removing more things than necessary. This is quite possibly the simplest thing I've ever done to the KJ. Not hard at all... just time consuming.

100,000 miles

Hello, the user manual for a KJ 2006 65th edition RWD with 3.7L engine recommends to change sparkplugs at 100,000 miles, it is getting close, but is really necessary if its running good? now if it is which brand are recommended for the best MPG? Thanks for the time and help

Roberto said:

Hello, the user manual for a KJ 2006 65th edition RWD with 3.7L engine recommends to change sparkplugs at 100,000 miles, it is getting close, but is really necessary if its running good? now if it is which brand are recommended for the best MPG? Thanks for the time and help

Click to expand...

Change every 30,000 miles with NGK coppers just like it says on the radiator cross member

Roberto said:

Hello, the user manual for a KJ 2006 65th edition RWD with 3.7L engine recommends to change sparkplugs at 100,000 miles, it is getting close, but is really necessary if its running good? now if it is which brand are recommended for the best MPG? Thanks for the time and help

Click to expand...

If you don't change them (and more frequently than every 100k), you'll likely NEVER change them. Either because you will feel that it is running fine and so why bother ... or because the spark plugs will have rusted and seized into the cylinder heads and will never come out without a machine shop and lots of drilling.

As Tom said... only NGK copper plugs, and change more frequently as the vehicle states. Its $25USD for a set of plugs... just do it.

I just got a set of 6 from rock auto for 13$ shipped