Electronic Distributorless Ignition System (EDIS)

1.9L SEFI EDIS System and Component Description

System Description

The 1 .9L SEFI Electronic Distributorless Ignition System (EDIS) consists of a Variable-Reluctance Sensor (VRS), an EDIS Ignition Module, an EEC-IV processor and one 4-Tower Coil Pack.

The Electronic Distributorless Ignition System (EDIS) operates by sending crankshaft position information from the VR sensor to the EDIS module. The module generates a PIP signal and sends it to the EEC-IV processor. The processor responds with a Spark Angle Word (SAW) signal containing advance or retard timing information back to the EDIS module. The module processes the VRS and SAW signals and decides which coils to fire. In addition, the module generates an Ignition Diagnostic Monitor (IDM) signal to the processor which is used to indicate a failure mode and also provide a tach output signal.

Component Description

VR Sensor

The VR sensor is a passive electromagnetic device which senses movement of a 36 minus one-tooth wheel located behind the crankshaft pulley. An A/C voltage signal is generated which increases with engine rpm and provides engine speed and crankshaft position information to the EDIS module.






Component Description

EDIS Module

The EDIS Module is a microprocessor-based device with coil drivers which make decisions about spark timing and coil firing. The module turns the coils on and off at the correct time and in the proper sequence based on information from the VR sensor and a pulse-width modulated signal (SAW) generated from the EEC-IV processor. The module receives VRS and SAW signals and produces PIP and IDM output signals which are sent to the EEC-IV processor.






EEC-IV Processor

The EEC-IV Processor receives IGN GND and PIP signals from the EDIS module, then generates a SAW output signal based upon engine speed, load, temperature and other sensor information. An IDM signal is received from the EDIS module to determine if an ignition failure mode should be recorded.






Component Description

Coil Pack

The coil is turned on (coil charging) by the EDIS module, then turned off, firing two spark plugs at once. One is for the cylinder which is to be fired (on compression stroke) and the other goes to the mating cylinder which is on the exhaust stroke. The next time the coil is fired, the situation is reversed. The next pair of spark plugs will fire according to the engine firing order, etc.






Repetitive Spark

Repetitive Spark is used to improve idle stability. It is enabled by the EEC-IV program below 1000 rpm. If in the repetitive spark mode after the first spark is sent to a pair of spark plugs, the plugs will be re-struck three more times very quickly. The repetitive spark primary waveform can be seen using a engine analyzer with DIS/EDIS capability.

Note: The required tachometer adapter (Rotunda 007-00061) is compatible with all Ford DIS/EDIS vehicles and is also compatible with the repetitive spark mode. A standard tachometer may not be compatible with this vehicle.