FUNCTION
The ECM calculates the most appropriate ignition timing and the time that current is applied to the primary windings of the ignition coil based on the signals sent from various sensors.
The ECM then sends an ignition command signal to the igniter of the ignition coil assembly.
The ignition timing is obtained using the following formula:
Ignition timing = A or B + C
Where: A: Base ignition timing, B: Basic advance, C: Compensation advance
| A. Fixed advance characteristics | The base ignition timing is 10° BTDC. It is fixed to 5° BTDC while the engine is starting. |
| B. Basic advance characteristics | The most appropriate ignition timing is selected from a map based on the signals from a variety of sensors. |
| C. Compensation advance characteristics | The ignition timing is advanced or retarded depending on the signals from a variety of sensors. |
| C-1. Warm engine advance characteristics | When the engine coolant temperature is low, the ignition timing is advanced in accordance with driving conditions to enhance driveability. |
| C-2. Idle stabilization advance characteristics | If the idle speed drops, the ignition timing is advanced to stabilize the idle speed. If the idle speed increases, the ignition timing is retarded. |
| C-3. Transition compensation retard | To prevent knocking, the ignition timing is retarded during sudden acceleration at a coolant temperature of 50°C (122°F) or more. |
| C-4. Timing retardation during fuel cut recovery | The ignition timing is retarded when the engine is recovered from fuel cut control, reducing shock. |
| C-5. Retard when accelerating | The ignition timing is temporarily retarded during acceleration to enhance driveability. |
| C-6. Knock compensation retard | If knock occurs, the ignition timing is corrected based on the signal from the knock control sensor. |
| C-7. Timing advance during EGR adjustment* | Adjustment is performed to advance the ignition timing in accordance with the EGR volume. |
*: Models with EGR control system