2.3L Mustang

The 2.3L Mustang (Dual Plug) Distributorless Ignition System (DIS) consists of a crankshaft-mounted dual Hall Effect sensor, two 4-tower DIS coil packs and a DIS ignition module.

The DIS eliminates need for a distributor by using multiple ignition coils. Each coil fires two spark plugs at same time. Spark plugs are paired so as one fires during the compression stroke, the other fires during the exhaust stroke. The next time same pair of plugs are fired, the roles are reversed. Although spark in exhaust stroke is wasted, little of coil's energy is lost.

Two coils are mounted together in a coil pack. Each coil pack has two tach wires: one for each coil. Since there are two plugs per cylinder, two coil packs are required. The right coil pack operates continuously, but the left coil may be switched on or off by ECA. The ECA computes spark angle and dwell for the ignition system.

The crankshaft sensor is a dual digital output Hall Effect device that responds to two rotating metallic shutters mounted together on the crankshaft. One output from Hall Effect senor, Profile Ignition Pick-up (PIP), is a 50 percent duty cycle signal (50 percent on and 50 percent off) that provides base spark timing information. The other output signal, Cylinder Identification (CID), is required so the DIS module knows which coil to fire. The CID is also used by ECA for fuel timing.

The ECA determines spark angle using PIP signal to establish base timing. The Spark Output Signal (SPOUT) is produced and sent by ECA to the DIS module and serves two purposes. The leading edge fires the coil, and the trailing edge controls dwell time. This feature is called Computer Controlled Dwell (CCD).

The Ignition Diagnostic Monitor (IDM) is an output signal from the DIS module to the ECA that provides diagnostic information about the ignition system for Self-Test.

Dual Plug Inhibit (DPI) allows the ECA to switch ignition system from single-plug to dual-plug operation. During engine cranking, vehicle is in the single-plug mode; only plugs on right side of the engine are firing. The ECA sends a command to DIS module to switch to dual-plug operation.

If CID circuit fails, DIS module will randomly select one of 2 coils to fire. If hard starting results, turning key off and then cranking again will result in DIS module selecting another coil to fire. Several attempts may be needed until proper coil is selected, allowing vehicle to be started and driven until repairs can be made. The Failure Mode Effects Management (FMEM) system will keep the vehicle drivable in the event of EEC-IV system or ignition failures that would otherwise prevent spark angle or dwell commands. During FMEM, ECA opens the SPOUT line and DIS module fires coils directly from PIP output. This results in a fixed spark angle of 10 degrees and fixed dwell.