Ignition Control System

IGNITION CONTROL SYSTEM
This system controls electronically the time of electric current flow to ignition primary coil as well as ignition timing. ECM (PCM) judges the engine and vehicle conditions by using signals from various sensors, selects the most suitable electric current flow time and ignition timing for that engine and vehicle conditions from among those prestored in its memory and sends an ignition signal to the igniter (power unit) in ignition coil assembly.
Control of this system includes three different types as follows.
- Ignition timing control at engine start
- Ignition timing control after engine start
- Electric current flow time control

Ignition Timing Control at Engine Start (Initial Ignition Timing)
To obtain better starting performance of the engine at the engine start (when the engine speed is lower than 500 r/min.), ignition control system sets the ignition timing to the initial ignition timing (5° BTDC.)
Also, the initial ignition timing (5° BTDC) is restored when all of the following conditions are met.
- Diag. switch terminal not grounded
- Test switch terminal grounded
- Throttle valve at closed throttle position (Idle)
- Engine speed lower than 2,000 r/min (rpm)

Ignition Timing Control After Engine Start
The ignition timing after the engine start is determined as follows so that the spark occurs at the most suitable timing for each engine and vehicle conditions.

Basic ignition advance
The basic ignition advance is determined by the engine coolant temperature, engine speed and intake manifold pressure.

Compensating advance
Listed below are different types of compensation each of which is added depending on the engine and vehicle conditions.
- Coolant temperature compensating advance
- Intake air temperature compensating advance
- Idling compensating advance
- Acceleration compensating advance

Electric Current Flow Time Control
To stabilize the secondary voltage generated in the ignition coil to a proper level, ignition control system controls the time of primary current flow to the ignition coil.

NOTE:
- The ignition timing is controlled by ECM (PCM) as described above. Therefore, when checking the ignition timing, the ignition timing must be fixed to the initial one by grounding the test switch terminal or by using SUZUKI scan tool.
- The initial ignition timing and ECM (PCM) controlled ignition timing are not adjustable. If they are found out of specification when inspected, check the CKP sensor, crankshaft timing belt pulley and related input signals.