Difficulty

Moderate

Steps

4

Time Required

                          1 hour

Sections

1

  • Spark Plugs
  • 4 steps

Flags

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  • Back1999-2004 Jeep Grand Cherokee WJ

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Introduction

What you need

Step 1

              Spark Plugs
  • The 4.0L 6–cylinder engine uses a one-piece coil rail containing three independent coils. Located on the right hand side (passenger side) of the engine.
  • The one-piece coil bolts directly to the cylinder head with 4 13mm hex bolt (M8X50). 3 of the bolts are immediately visible.
  • The fourth one is somewhat hidden in the back, under the coolant lines for the heater. The hoses can easily be moved out of the way.

The 4.0L 6–cylinder engine uses a one-piece coil rail containing three independent coils. Located on the right hand side (passenger side) of the engine.

The one-piece coil bolts directly to the cylinder head with 4 13mm hex bolt (M8X50). 3 of the bolts are immediately visible.

The fourth one is somewhat hidden in the back, under the coolant lines for the heater. The hoses can easily be moved out of the way.

1024

Step 2

  • Start removing the 13mm bolts from the coil rail. Use an extension will make it easier to clear the radiator hoses and throttle cables.
  • Use a smaller extension to remove the 4th bolt in the back of the rail.
  • All 4 bolts are identical in size and need not to be separated.

Start removing the 13mm bolts from the coil rail. Use an extension will make it easier to clear the radiator hoses and throttle cables.

Use a smaller extension to remove the 4th bolt in the back of the rail.

All 4 bolts are identical in size and need not to be separated.

Step 3

  • With all 4 bolts removed, the rail should easily pull off the spark plugs. One electrical connector (located at the rear end of the coil rail) is used for all three coils. It is not necessary to totally remove the rail for a spark plug change.
  • Rubber boots seal the secondary terminal ends of the coils to the top of all 6 spark plugs.
  • Use a 5/8inch spark plug socket and extension to remove the spark plug. Again, the ignition rail can be easily moved out of the way.

With all 4 bolts removed, the rail should easily pull off the spark plugs. One electrical connector (located at the rear end of the coil rail) is used for all three coils. It is not necessary to totally remove the rail for a spark plug change.

Rubber boots seal the secondary terminal ends of the coils to the top of all 6 spark plugs.

Use a 5/8inch spark plug socket and extension to remove the spark plug. Again, the ignition rail can be easily moved out of the way.

Step 4

  • Continue to remove all spark plugs.
  • To remove the last spark plug in the rear, use a longer extension. Always ensure that the socket is properly seated on the spark plug.
  • With all spark plugs removed, it is clearly visible that these plugs were in definite need to be replaced.

Continue to remove all spark plugs.

To remove the last spark plug in the rear, use a longer extension. Always ensure that the socket is properly seated on the spark plug.

With all spark plugs removed, it is clearly visible that these plugs were in definite need to be replaced.

To reassemble your device, follow these instructions in reverse order. Always use a spark plug socket that has a rubber insert to hold the spark plug into the socket. Use the socket and a extension without a ratchet to hand tighten the spark plugs. Ensure that they can be easily screwed into the spark plug hole. There is always a risk of cross threading when using the ratchet. Position ignition coil rubber boots to all spark plugs. Push down on coil assembly until bolt bases have contacted the cylinder head. Install 4 coil mounting bolts. Loosely tighten 4 bolts just enough to allow bolt bases to contact cylinder head. Do a final tightening of each bolt in steps down to 29 N·m (250 in. lbs.) torque. Do not apply full torque to any bolt first.

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                                                                                      37 other people completed this guide.

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                    oldturkey03

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triguno72 - Mar 20, 2016

Reply

Nice job I like the pic and gould understand 100 percent I which that all pic would be like t hese thanks again wonderful I give him not 30 a at 100

Rudy Garcia - Apr 6, 2016

Reply

This is great, my jeep has a misfire on cylinder 4 and this helped me locate and get to the coil and spark plug, straight forward easy to follow, thank you, I will update once i’m done.

Rudy Garcia - Apr 7, 2016

Reply

Finished replacing the plugs, my check engine light went away, misfire is gone, thank you!

Majed Badghaish - Sep 24, 2016

Reply

well done, great post

thank you..

Barrett Snyder - Apr 18, 2017

Reply

Very nice detailed instructions. The illustrations make it very simple to follow. The list of tools is exactly whats required. Thank you for putting the time in for such detailed instructions for a task that is very important to fuel economy as well as power/torque.

Even the plug gap and type are supplied. Thanks again.