Subsections

Idle Advance

• Idle Advance Settings
• Idle Advance Tuning
  • Tuning Idle Advance Engagement Settings
  • Tuning Idle Advance Timing

Idle Advance

The Idle Advance feature is useful to fine-tune ignition timing at idle. It is particularly useful to help catch sudden load increases on the engine at idle by increasing timing when load increases to help the engine generate more power, keeping RPM from dropping severely.

Idle Advance Settings

This section describes the Idle Advance settings.

• Idle advance on
  • On - Turn the idle advance feature on.
  • Off - Turn the idle advance feature off.
• TPS is below (%) - The TPS must be below this value before idle advance will engage.
• and RPM is below (rpm) - The RPM must also be below this value before idle advance will engage.
• and load is above (%) - The engine load must also be above this value before idle advance will engage.
• and CLT is above (degrees) - The engine coolant temperature must also be above this value before idle advance will engage.
• and after delay (sec) - All the other conditions must be met for this amount of time before idle advance will engage.
• Idle Advance Timing curve - This is a four-point curve with Load as the X-axis and timing as the Y-axis. This curve determines the actual timing once the idle advance feature has engaged.

Idle Advance Tuning

There are two main types of settings to tune for the Idle advance feature:

• Idle Advance engagement settings - These settings control the conditions under which Idle Advance will engage.
• Idle Advance Timing curve - This curve controls the actual ignition timing once all the Idle Advance engagement conditions have been met.

Tuning Idle Advance Engagement Settings

The Idle Advance engagement settings should be set so that idle advance will engage in roughly the same conditions that occur during normal, warmed-up idle.

Settings recommendations:

Go to idle advance when:

• TPS is below - This setting should be set as low as possible. Typically settings between 0.5% and 1% should be used. If numbers that are too low are used, then idle advance may not engage if there is some play in the throttle body or there are minor electrical fluctuations that cause the closed TPS % to vary. If numbers that are too high are used, then idle advance may engage at undesirable times.
• and RPM is below - This setting should typically be set just above the desired idle RPM, and below the lowest RPM at which the driver normally drives in gear. For example, if the desired idle RPM is 800, then a good value for this setting is 1000.
• and load is above - This setting should be set just below the load value seen during a normal idle with no load on the engine.
• and CLT is above - This setting should be set to the temperature at which the engine idle characteristics no longer change. Generally this is when the engine is fully warm.
• and after delay - This setting should be set to a value that is long enough for the engine RPM and load to become stable before idle advance engages.

Tuning Idle Advance Timing

In general, the most stable idle is reached by decreasing the idle timing, and increasing the amount of air entering the engine (using an idle air valve or similar). As such the idle advance timing should be as low as possible while retaining a smooth idle. Since less timing is used during normal idle conditions, as load increase, the timing should also increase to counteract RPM decrease when the load increases.