Electronic Ignition (EI) (High Data Rate) System: 4.0L

WARNING: This page is about a different car, the 1995 Ford Aerostar. However, it is still accessible from the selected car via links, so may be relevant.

The EI (high data rate) system (formerly Electronic Distributorless Ignition System EDIS) consists of a Crankshaft Position (CKP) sensor, Ignition Control Module (ICM) and one 6-tower coil pack.

The EI system operates by sending crankshaft position information from CKP sensor to ICM. The ICM generates a Profile Ignition Pick-Up (PIP) signal and sends it to the PCM.

The PCM responds with a Spark Output (SPOUT) signal containing advance or retard timing information back to the ICM. The ICM processes the CKP and SPOUT signals and decides which coils to fire. Also, the ICM generates an Ignition Diagnostic Monitor (IDM) signal to PCM, which is used to provide a tach output signal and indicate a failure mode if detected.

The CKP sensor is an electromagnetic device that senses movement of a 35-tooth wheel, located behind the crankshaft pulley. Each tooth is positioned in 10-degree increments, with an empty slot (missing tooth) located 90 degrees BTDC. The detection of the missing tooth enables the PCM to identify crankshaft position and initiate correct firing order.

The ICM is a microprocessor with coil drivers. ICM strategy controls spark timing and coil firing. The ICM turns coils on and off at the correct time and in proper sequence, based on information from CKP sensor and a pulse width modulated signal (SPOUT) generated from PCM. The ICM receives CPK sensor and SPOUT signals and produces PIP and IDM output signals, which are sent to PCM.

The PCM receives ignition ground and PIP signals from the ICM, and then generates a SPOUT output signal based on engine speed, load, temperature and other sensor information. An IDM signal is received from ICM to determine if an ignition failure mode should be recorded.

The coil is turned on (coil charging) and then off by ICM, firing 2 spark plugs at once. One plug is fired on the compression stroke; the other plug fires the mating cylinder, which is on the exhaust stroke. On the next cycle, firing strategy is reversed.