Coil Pack Pins

Identify the connector pins on the ignition coil assembly. If you look at the electrical connector you unplugged on the ignition coil assembly, you will see three small pins inside. The one in the center is B+. 

Fig. Fig. 2: Engine ignition coil harness connections-2.3L, 2.5L and 5.0L engines

Disconnect the spark plug wires from the ignition coils on the assembly by hand. The wires have a locking tab. To disconnect them squeeze the locking tabs inward at the terminal and twist the boot while pulling up. This also a good time to check the resistance of the spark plug wires and check for damage as you have them apart already.

Removing the coil pack and bench testing is best.  Often there is cracking and damage on the underside of the unit which only can be seen if it is removed and cleaned.

Get a multimeter (digital is best) and set it to the correct range for ohm testing.

Checking the ignition coils' primary resistance. Probe pins B+ and coil 1 of the connector on the ignition coil assembly, and make a note of the number on the multimeter readout. Then probe pins B+ and coil 2.  Make a note of each of your meter readouts. The resistance value for each pair of pins in your three tests should be between 0.3 and 1.0 ohms. If any of the coil packs (2 per unit) test out of this range (over or under), the pack should be replaced.

Check the ignition coils secondary resistance. Select the appropriate range in your multimeter so you can read between 6,500 and 11,500 ohms in the ohmmeter scale. Probe the two terminals on coil 1, where the spark plug wires 1 and 4 connect to, and make a note of your multimeter readout number. Probe the terminals on coil 2 and 3 and make a note of the results, as well. Any coil that tests outside of the 6,500 through 11,500 ohms range should be replaced. On 2.3L, 2.5L and 5.0L engines, if one coil pack is found to be defective, the other pack does not need to be replaced.

If any pack tested bad in either test, replace the unit.

The condenser usually mounted to the coil pack goes bad often creating a ignition miss, replace this item.

If the pack is good, reconnect the electrical plug, spark plug wires and the negative battery cable. 

Other sensors that effect the timing are: MAP ( Manifold Absolute Pressure sensor ), IAT ( Intake Air Temperature sensor ), ECT ( Engine Coolant Temperature sensor ), EVP ( EGR Valve Position sensor ) and TPS ( Throttle Position Sensor ).