To install the spark plug for the 4.0L engine, start each spark plug by hand to avoid cross threading and damage, using a quality socket with a rubber insert. Tighten the spark plugs to 27 Nm (20 ft. lbs.), then install ignition coil 3 and bolt 2, tightening the bolt to 8 Nm (71 in. lbs.). Connect electrical connector 1 to ignition coil 3, followed by the installation of the intake manifold. After that, install the engine cover and connect the negative battery cable, tightening the nut to 5 Nm (45 in. lbs.).