DISTRIBUTORLESS Ignition System
The Distributorless Ignition System (DIS) uses the Engine Control Module (ECM) for determining ignition timing (spark advance). The ECM determines ignition timing (spark advance) based on various input signals. Following input signals may be used: engine coolant temperature, oxygen sensor, airflow meter, engine RPM, throttle position, vehicle speed sensor, park/neutral position switch, A/C switch, cranking (starter) signal and knock sensor.
Conventional distributor and pick-up coil have been replaced by a camshaft and crankshaft position sensor. Camshaft position sensor and crankshaft position sensor deliver input signals to Engine Control Module (ECM). The ECM detects the standard crankshaft position based on camshaft position sensor input signals, and the actual crankshaft position and engine speed by the crankshaft position sensor input signals. Camshaft position sensor is located at flywheel end of driver's side (front) cylinder head, just below valve cover. See Figure. Crankshaft position sensor is located at front of crankshaft, near crankshaft pulley. See Figure.
The ECM uses 3 ignition primary control signals to the ignitor for the ignition coils. The DIS uses 3 ignition coils which fire 2 cylinders simultaneously using the same ignition coil. See Fig 1. Cylinder No. 1 is front cylinder on right side of engine when viewed from flywheel end of engine. Cylinder No. 2 is front cylinder on left side of engine when viewed from flywheel end of engine. Cylinders No. 1, 3 and 5 are on right side of engine. Cylinders No. 2, 4 and 6 are on left side of engine.
One ignition coil is mounted on top of spark plug on cylinders No. 2, 4 and 6. Spark plug wires are routed from ignition coils on top of spark plugs to the spark plugs on the remaining cylinders. The ECM monitors IGF circuit at the ignitor to ensure ignition coils have fired.