Ignition Coil: Service and Repair

COIL RAIL

REMOVAL

Fig.13 Ignition Coil Assembly - 4.0L 6-Cylinder Engine:

A one-piece coil rail assembly containing three individual coils is used on this engine (Fig. 13). 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.

Fig.14 Ignition Coil Rail Location - 4.0L 6-Cylinder Engine:

2. The coil is bolted directly to the cylinder head. Remove 4 coil mounting bolts.
3. 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.

Fig.15 Ignition Coil Electrical Connector - 4.0L 6-Cylinder Engine:

4. 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.
5. Remove coil from vehicle.

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