Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.
Description and Operation 1-79
Ignition Systems
Ignition Systems
Overview
The ignition system is designed to ignite the compressed air to fuel mixture in an internal combustion engine by a high voltage spark delivered from an ignition coil controlled by the powertrain control module (PCM).
Integrated Electronic Ignition System
NOTE: Electronic ignition engine timing is controlled entirely by the PCM. Electronic ignition engine timing is not adjustable. Do not attempt to check base timing. You will receive false readings.
The integrated electronic ignition system consists of a crankshaft position (CKP) sensor, coil pack or coil on plug (COP), connecting wiring, and a PCM. For additional information on the ignition system components, refer to Engine Control Components in this section. The COP integrated electronic ignition system uses a separate coil per spark plug, and each coil is mounted directly onto the plug. The COP integrated electronic ignition system eliminates the need for spark plug wires, but does require input from the camshaft position (CMP) sensor. Operation of the components are as follows:
1. The CKP sensor indicates the crankshaft position and speed by sensing a missing tooth on a pulse wheel mounted to the crankshaft. The COP integrated electronic ignition system uses the CMP sensor to identify the compression stroke of cylinder 1, and to synchronize the firing of the individual coils.
2. The PCM uses the CKP sensor signal to calculate a spark target and then fires the coil pack or COP to that target shown. The PCM uses the CMP sensor signal to identify the compression stroke of cylinder 1, and to synchronize the firing of the individual coils.
3. The PCM controls the ignition coils after it calculates the spark target. The COP system fires only one spark plug per coil upon synchronization during the compression stroke. For the coil pack ignition system, each coil within a pack fires 2 spark plugs at the same time. The plugs are paired so that as one fires during the compression stroke the other fires during the exhaust stroke. The current flow, or dwell, through the primary ignition coil is controlled by the PCM by providing a switched ground path through the ignition coil driver to ground. When the ignition coil driver is switched ON, current rapidly builds up to a maximum value, determined by the coil inductance and resistance. When the current is switched OFF, the magnetic field collapses which induces a secondary high voltage surge and the spark plug is fired. This high voltage surge creates a flyback voltage which the PCM uses as a feedback during the ignition diagnostics. The PCM uses the charge current dwell time characteristics to carry out the ignition diagnostics.
4. The PCM processes the CKP sensor signal and uses it to drive the tachometer as the clean tach output (CTO) signal.
Integrated Electronic Ignition System
2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.