Ignition System: Description and Operation

Ignition System Construction

The ignition system is an electronic (distributor less) ignition system. Especially, a direct ignition system is adopted. They consists of the parts as described below.
^ ECM
It detects the engine and vehicle conditions through the signals from the sensors, determines the most suitable ignition timing and time for electricity to flow to the primary coil and sends a signal to the ignitor (power unit) in the ignition coil assembly.

^ Ignition coil assembly (including an ignitor)
The ignition coil assembly has a built-in ignitor which turns ON and OFF the current flow to the primary coil according to the signal from ECM. When the current flow to the primary coil is turned OFF, a high voltage is induced in the secondary coil. One ignition coil is in charge of ignition of one cylinder only.

^ Spark plugs

^ CMP sensor and CKP sensor
Using signals from these sensors, ECM identifies the specific cylinder whose piston is in the compression stroke, detects the crank angle and adjusts initial ignition timing automatically.

^ TP sensor, ECT sensor, MAF sensor, IAT sensor, knock sensor, wheel speed sensor (VSS) and other sensors / switches

Although ignition system does not have a distributor and high-tension cords, each cylinder has an ignition coil assembly (ignitor and ignition coil) and the secondary voltage which occurred in the ignition coil is sent to the spark plug directly. Also, the signal (s) are sent from the CMP sensor to ECM so as to control each ignition coil independently through the ignitor (in ignition coil assembly).