Direct Ignition System & Integrated Direct Ignition

The Direct Ignition System (DIS) is a distributorless system used on 1.9L, 2.2L, 3.1L, 3.4L and 4.6L. The 2.4L uses a similar system referred to as the Integrated Direct Ignition (IDI) system. The DIS systems consist of 2 (4-cylinder) or 3 (V6) ignition coils, Ignition Control Module (ICM), located under the coil pack, a Camshaft Position (CMP) sensor, 2 hall-effect Crankshaft Position (CKP) sensors, necessary wiring, and the ignition control and fuel metering portion of the PCM. On the 2.4L IDI system, ignition coils, ICM and spark plug connectors are all combined into one unit which plugs directly onto the spark plugs.

Spark is timed by a signal sent from a CKP sensor, mounted through side of engine block. This signal goes through the ICM, is received by PCM and is used to trigger each coil at the proper time. See CRANKSHAFT POSITION SENSOR  under INPUT DEVICES. Each cylinder is fired consecutively with the companion cylinder in the firing order. On V6, cylinder No. 1 is paired with No. 4, No. 2 with No. 5, and No. 3 with No. 6. On 4-cylinder, cylinder No. 1 is paired with No. 4 and cylinder No. 2 is paired with No. 3. Each pair of cylinders is fired by its own ignition coil.

On all models except Saturn and 4.6L, CKP sensor is mounted near the ICM. On Saturn, CKP sensor is mounted on side of engine block. On 4.6L, CKP sensors ("A" and "B") are mounted on side of engine block between cylinders No. 4 and 6. On all models, the CKP sensor protrudes through the side of engine block to within .05" (1.3 mm) of an internally-mounted crankshaft reluctor ring. Sensor position is not adjustable.

The reluctor is a piece of metal, cast with the crankshaft. On all models except 4.6L, reluctor has 7 slots machined into it, 6 of which are equally spaced (60 degrees apart). The seventh slot is spaced about 10 degrees from one of the other slots and generates a synchronization pulse signal. On 4.6L, reluctor has 24 evenly spaced notches machined into it and an additional 8 unevenly spaced notches for a total of 32. On all models, as crankshaft rotates, notches in reluctor ring change the magnetic field at the tip of position sensor. This creates an induced AC voltage signal in the sensor windings, resulting in RPM reference signals which are sent to PCM by the ICM. This allows PCM to compute crankshaft position and RPM.