Ignition system (Chevrolet Aveo T250)

This ignition system does not use a breaker-distributor and coil. Instead, it uses a crankshaft position sensor that sends a signal to the engine control module (ECM). The ECM then generates the ignition timing (EST) and fires the ignition coil directly.

This type of ignition system without a distributor breaker operates on the "excess spark" method. The cylinders are paired with opposite (1-4 or 2-3). The spark occurs simultaneously in the cylinder in which the piston is in the compression phase and in the cylinder in the exhaust phase. The cylinder in the exhaust phase requires a very small amount of energy to spark the spark plug. The remaining energy is used by the spark plug in the cylinder in the compression phase. The ignition coil cannot be repaired, so the entire unit must be replaced.

These systems use the EST signal from the ECM to control the electronic ignition system. The ECM uses the following data:

• engine load (manifold pressure or vacuum);
• atmospheric (barometric) pressure;
• engine temperature;
• supply air temperature;
• crankshaft position;
• engine speed (rpm).

[The original text can be found on the website: ChevyMan]