Liberty, Wrangler, 1997-2005

Ignition Coil

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An individual ignition coil is used for each spark plug . The coil fits into machined holes in the cylinder head. A mounting stud/nut secures each coil to the top of the intake manifold. 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 is used to seal the coil at the opening into the cylinder head.



Before removing or disconnecting any spark plug cables, note their original position. Remove cables one-at-a-time. To prevent ignition crossfire, spark plug cables MUST be placed in cable tray (routing loom) into their original position.
 
An individual ignition coil is used at each cylinder.
 
The coil mounts to the top of the valve cover with two bolts . 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.
 

Removal & Installation



2.4L Engine
  1. Disconnect electrical connector at rear of coil.
  2.  
  3. Remove all secondary cables from coil.
  4.  
  5. Remove 4 coil mounting bolts .
  6.  
  7. Remove coil from vehicle
  8.  

To install:

  1. Position coil to engine.
  2.  
  3. Install 4 mounting bolts.
  4.  
  5. Install secondary cables.
  6.  
  7. Install electrical connector at rear of coil.
  8.  
  9. Install air cleaner tube and housing.
  10.  

  1. Disconnect electrical connector at rear of coil.
  2.  
  3. Remove all secondary cables from coil.
  4.  
  5. Remove 4 coil mounting bolts .
  6.  
  7. Remove coil from vehicle.

    Click image to see an enlarged view

    Fig. Removal and installation of the ignition coil on the Liberty

  8.  

To install:

  1. Position coil to engine.
  2.  
  3. Install 4 mounting bolts.
  4.  
  5. Install secondary cables.
  6.  
  7. Install electrical connector at rear of coil.
  8.  
  9. Install air cleaner tube and housing.
  10.  

3.7L Engine

An individual ignition coil is used for each spark plug . The coil fits into machined holes in the cylinder head. A mounting stud/nut secures each coil to the top of the intake manifold . 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 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.  
  3. Disconnect electrical connector from coil by pushing downward on release lock on top of connector and pull connector from coil.
  4.  
  5. Clean area at base of coil with compressed air before removal.
  6.  
  7. Remove coil mounting nut from mounting stud.
  8.  
  9. Carefully pull up coil from cylinder head opening with a slight twisting action.
  10.  
  11. Remove coil from vehicle.

    Click image to see an enlarged view

    Fig. Ignition coil mounting bolts for the Liberty

  12.  

To install:

  1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
  2.  
  3. Check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil O-ring.
  4.  
  5. Position ignition coil into cylinder head opening and push onto spark plug. Do this while guiding coil base over mounting stud.
  6.  
  7. Install coil mounting stud nut.
  8.  
  9. Connect electrical connector to coil by snapping into position.
  10.  
  11. If necessary, install throttle body air tube or box.
  12.  

4.0L Engine


Click image to see an enlarged view

Fig. The removal and installation of the ignition coil on the 4.0L engine

A one-piece coil rail assembly containing three individual coils is used on the 4.0L engine. The coil rail must be replaced as one assembly. The bottom of the coil is equipped with 6 individual rubber boots to seal the 6 spark plugs to the coil. Inside each rubber boot is a spring. The spring is used for an electrical 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.

  1. Disconnect negative battery cable at battery.
  2.  
  3. The coil is bolted directly to the cylinder head.
  4.  
  5. Remove 4 coil mounting bolts .
  6.  
  7. Carefully pry up coil assembly from spark plugs. Do this by prying alternately at each end of coil until rubber boots have disengaged from all spark plugs. If boots will not release from spark plugs, use a commercially available spark plug boot removal tool. Twist and loosen a few boots from a few spark plugs to help remove coil.
  8.  
  9. After coil has cleared spark plugs, position coil for access to primary electrical connector. Disconnect connector from coil by pushing slide tab outwards to right side of vehicle . After slide tab has been positioned outwards, push in on secondary release lock on side of connector and pull connector from coil.
  10.  
  11. Remove coil from vehicle.
  12.  

To install:

  1. Connect engine harness connector to coil by snapping into position. Move slide tab towards engine for a positive lock.
  2.  
  3. Position ignition coil rubber boots to all spark plugs. Push down on coil assembly until bolt bases have contacted cylinder head.
  4.  
  5. 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 250 inch lbs. (29 Nm) torque. Do not apply full torque to any bolt first.
  6.  
  7. Connect negative battery cable to battery.
  8.  

Testing



To perform a complete test of the eight ignition coils and their circuitry, refer to the DRB scan tool. To do an individual test of the coil only, refer to the following:

Inspect the ignition coil for cracks and for any arcing. Arcing at the secondary end will carbonize the rubber spark plug boot, which if it is reconnected, may cause the coil to fail. Replace coil if any cracks or arcing is found.

Test the resistance (in ohms) of the primary side of the coil by attaching an ohmmeter across the two pins at the electrical connector end of the coil.

Test the resistance (in ohms) of the secondary side of the coil by attaching an ohmmeter from either of the two primary pins to the spring inside the rubber boot at the spark plug opening.

 
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