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, engine RPM, throttle position, vehicle speed sensor, Manifold Absolute Pressure (MAP) sensor, 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Conventional distributor and pick-up coil have been replaced by a camshaft and crankshaft position sensor.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 delivers input signal to terminal G2 ("G" signal) of ECM to indicate camshaft position. Crankshaft position sensor delivers input signal to terminal NE or NE+ of ECM to indicate crankshaft position. The ECM detects the standard crankshaft position based on camshaft position sensor signals and the actual crankshaft position and engine speed by the crankshaft position sensor. Camshaft position sensor is located at rear of cylinder head, just above the flywheel. Crankshaft position sensor is located behind lower timing belt cover, just above crankshaft sprocket.
The ECM uses 2 ignition primary control signals to the ignitor for the ignition coils. See Fig 1. The DIS uses 2 ignition coils which fire 2 cylinders simultaneously using the same ignition coil. Cylinders No. 1 and 4 fire together. Cylinders No. 2 and 3 fire together. Cylinder No. 1 is at timing belt of engine and cylinder No. 4 is at flywheel end of engine. One ignition coil is mounted on top of spark plug on cylinder No. 3 with spark plug wire going to cylinder No. 2 spark plug. One ignition coil is mounted on top of spark plug on cylinder No. 4 with spark plug wire going cylinder No. 1 spark plug. The ECM monitors IGF circuit at the ignitor to ensure ignition coils have fired.