The engine ECU, which receives signals from various sensors, calculates the ignition timing and transmits ignition signals to the igniter. The ignition timing is calculated continuously in accordance with the conditions of the engine, based on the optimal ignition timing values that are stored in the computer in the form of an ESA map. Compared to the mechanical ignition timing control of the conventional system, the control method with the ESA provides higher precision, and the freedom to set the ignition timing. As a result, this system offers improved fuel economy and power output.
The TDI is also known as DIS (Direct Ignition System) or DLI (Distributor- Less Ignition).
The direct ignition system consists of the following components:
1. Crankshaft position sensor (NE)
Detects the crankshaft angle (Engine speed).
2. Camshaft position sensor (G)
Identifies the cylinder and the stroke and detects the camshaft timing.
3. Knock sensor (KNK)
Detects the knocking of the engine.
4. Throttle position sensor (VTA)
Detects the opening angle of the throttle valve.
5. Air flow meter (VG/PIM)
Detects the amount of the intake air. (On some models, this detection is performed by a manifold pressure sensor)
6. Water temperature sensor (THW)
Detects the engine coolant temperature.
7. Ignition coil with igniter
Turns the primary coil current on and off at the optimal timing. Sends the IGF signal to the engine ECU.
8. Engine ECU
Generates an IGT signal based on
the signals from various sensors and
sends the signal to the ignition coil
9. Spark plug
Generates electric sparks to ignite
the air-fuel mixture.