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Ignition Timing - Primary, Decel, and Startup

For more information on the basics of Ignition Timing and Detonation, see: Ignition Timing and Knock Control.

Targets

Acceleration (or "Primary")

Base and Dynamic Advance

This target is active when the accelerator pedal is depressed, or otherwise when conditions are met for the parameter.png Ignition - Accel. Dynamics - Decel Active (⚑, ubyte) parameter to be zero. Generally speaking, conditions where this target is active are wide open throttle ("WOT") and cruising (when the accelerator is pressed).

This ignition timing target and its associated tables and parameters are sorted under the Ignition - Primary folder and are comprised of four key base tables:

  • table.png Ignition - Primary - TGVs Closed (AVCS Disabled)
  • table.png Ignition - Primary - TGVs Closed (AVCS Enabled)
  • table.png Ignition - Primary - TGVs Open (AVCS Disabled)
  • table.png Ignition - Primary - TGVs Open (AVCS Enabled)

These four tables are first blended based on the corresponding blending values of parameter.png Engine - AVCS Map Ratio (﹪, ubyte) and t parameter.png Engine - TGV Map Ratio (﹪, ubyte). The resulting base value can be monitored using the parameter.png Ignition - Primary - Base Table (°, sbyte) parameter.

Then, a Dynamic Advance value is calculated using the parameter.png Knock Control - Dynamic Advance Multiplier (ubyte), commonly referred to as "DAM". This DAM value ranges from 0.00 to 1.00 and acts as a multiplier to the base dynamic advance table value. This base dynamic advance value is found by using the two primary base tables that are themselves blended using the TGV Map Ratio:

  • table.png Ignition - Primary - Advance - TGVs Closed (Base)
  • table.png Ignition - Primary - Advance - TGVs Open (Base)

The resulting blended, base value can be monitored using the parameter.png Ignition - Primary - Advance - Table (°, ubyte) parameter. This value is summed with the parameter.png Ignition - Primary - Base Table (°, sbyte) to produce a primary base target value.

Tuning Strategy

Tuning the Primary Ignition target maps is critical for any power-related objectives in the Subaru DI platforms, as these tables are designed to control the spark advance in all typical acceleration scenarios when throttle is applied.

With the tables under the Ignition - Primary - Advance controlled by the Dynamic Advance Multiplier (or DAM), this presents an opportunity to you as a tuner to determine how ignition advance should be delivered in scenarios where the DAM is lowered. The DAM is reduced by negative ignition events such as detonation, therefore these associated tables can be used to design areas of the ignition timing advance that, were detonation to be identified, timing may be removed.

Deceleration (or "Decel")

This target is active when the accelerator pedal is depressed, or otherwise when conditions are met for the parameter.png Ignition - Accel. Dynamics - Decel Active (⚑, ubyte) parameter to be one. 

This ignition timing target and its associated tables and parameters are sorted under the Ignition - Decel. folder and are comprised of two key base tables:

  • table.png Ignition - Decel. - TGVs Closed
  • table.png Ignition - Decel. - TGVs Open

Control Systems

Accelerator Dynamics

Accelerator Dynamics is the control system that blends the Primary Ignition and Decel Ignition targets.

image.png

Hysteresis

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