The ESA (Electronic Spark Advance) system is a system that uses the engine ECU to determine the ignition timing based on the signals from the various sensors. The engine ECU calculates the ignition timing from the optimum ignition timing stored in memory to match the engine conditions, and then sends the ignition signal to the igniter. The optimum ignition timing is basically determined using.
The ESA system consists of the various sensors, engine ECU, igniters, ignition coil, and spark plugs.
Role of the sensors
Camshaft position sensor (G signal):
This detects the standard crank angle and the camshaft timing.
Crankshaft position sensor (NE signal):
This detects the crank angle and engine speed.
Air flow meter or manifold pressure
sensor (VG or PIM signal):
This detects the intake air mass or manifold pressure.
Throttle position sensor (IDL signal):
This detects the idling condition.
Water temperature sensor (THW
signal):
This detects the coolant temperature.
Knock sensor (KNK signal):
This detects knocking condition.
Oxygen sensor (OX signal):
This detects the oxygen concentration in the exhaust gas.
Role of the engine ECU
The engine ECU receives the signals from the sensors, calculates the optimum ignition timing for the engine conditions, and sends the ignition signal (IGT) to the igniter.
Role of the igniter
The igniter responds to the IGT signal output by the engine ECU to intermittently apply the primary current to the ignition coil. It also sends the ignition confirmation signal (IGF) to the engine ECU. engine speed and intake air mass (manifold pressure).