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, intake air temperature, 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Conventional distributor and pick-up coil have been replaced by a camshaft and crankshaft position sensor.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 the front of the cylinder head on the firewall side of the engine. See Figure. Crankshaft position sensor is located at front (timing belt end) of engine, behind timing belt cover, near sprocket on crankshaft. See Figure.
The ECM uses 2 ignition primary control signals to the ignitor for the ignition coils. The DIS uses 2 ignition coils with internal ignitors to fire 2 cylinders simultaneously using the same ignition coil. See Fig 1. Cylinders No. 1 and 4 fire together and 2 and 3 fire together. Cylinder No. 1 is front cylinder at timing belt end of engine and cylinder No. 4 is the rear cylinder at flywheel end of engine. Ignition coils are mounted on end of cylinder head, just below the valve cover. The ECM monitors IGF circuit at the ignitor to ensure ignition coils have fired. The ECM stops fuel injection as a fail-safe function when IGF reference signal has not been received.