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IDLE

IDLE RPM Table

The table specifies the desired idle speed depending on the engine temperature. Typically, the idle speed is higher when the engine is cold to ensure stable operation and faster warm-up, and decreases to the operating value as the engine warms up.

Minimum position

Sets the threshold below which the idle speed control (ICV) does not close. This is necessary to prevent the speed from dropping too low and the engine from stalling. It is recommended to set it 100–200 rpm below the target idle speed.

Addition after start

Sets the additional opening of the ICV immediately after starting the engine. This addition helps to avoid a sharp drop in speed in the first seconds of operation. Too much addition will cause the speed to “freeze” after start-up, too little will cause the engine to stall.

IAT compensation

Air temperature affects its density:

  • Hot air is less dense → ICV needs to be opened more to let more air through.
  • Cold air is denser → ICV can be opened less.

This parameter sets how much to change the minimum ICV position for every 20 °C deviation from the base air temperature (IAT) of 20 °C.

Pickup

A function that briefly maintains increased revs when the throttle is released so that the engine does not drop sharply to idle.

  • Pickup revs — how many revs above idle the regulator should “hold” the revs.
  • Pickup percentage — the difference in ICV opening percentage between normal idle speed and pickup. - Test — raises the target RPM by the pickup value for a few seconds, then returns it back. Convenient for tuning

Example:

  • RPM = 800, ICV position is 25%.
  • Pickup RPM is 300.
  • Increase RPM by 300, now RPM is 1100, ICV position is 28%.
  • Pickup percentage: 28-25 = 3%.

Manual control

When the slider is set to 0, automatic control is activated — the ECU controls the idle valve according to the configured algorithm.

If you move the slider to any position other than 0, the system will switch to manual control mode. In this case, the valve position will be fixed according to the selected slider value, and the automatic algorithm will be temporarily suspended. As soon as the slider returns to 0, automatic control will resume.

💡 Tip: Manual control mode is useful for:

  • testing the valve operation
  • checking the engine response to different ICV positions
  • temporarily maintaining the speed without changing the basic settings

Idle cut-off

The idle cut-off function is activated when the accelerator pedal is fully released while driving in gear. This saves fuel and reduces emissions.

  • Upper limit - RPM above which fuel supply is cut off
  • Lower limit - RPM below which fuel supply is resumed
  • Delay - Time between releasing the accelerator pedal and the moment when fuel supply is stopped

🔧 Setting tip:

  • Too high an upper limit can reduce fuel economy.
  • A lower limit that is too low can cause jerks when fuel is re-supplied and RPM drops below idle speed

Corrections

These parameters compensate for changes in engine load when turning the air conditioner on/off or shifting gears to avoid RPM jumps.

  • For the air conditioner turned on, you can set the idle speed separately.
  • In the On and Off fields, you can set the ICV position correction, which is added or subtracted when the load status changes.

The values are selected experimentally so that the moment of turning the load on or off is imperceptible to the driver.

💡 Example: if the speed drops briefly by 150 rpm when the air conditioner is turned on, you can increase the ICV position in the On field by a few percent until the drop disappears.

PID

Ki setting

Ki is the most important coefficient in the idle speed regulator. It determines the speed at which the revs return to the target value in case of small deviations.

Example: You turn on the air conditioner → the RPM drops → the regulator gradually raises it. The speed of this rise is set by Ki.

Setting procedure:

  • Set the IDR value to 800 rpm in the table and wait for stabilization.
  • Change the value of XX to 1200 rpm and wait for stabilization again.
  • Repeat steps 1–2, selecting Ki so that the speed is set within 3–4 seconds after the change.

Kp setting

Kp determines how quickly the regulator responds to large speed deviations. It is responsible for sudden changes — for example, when you suddenly change the target speed or under heavy loads.

Setting procedure:

  • Set IDL = 800 rpm and wait for stabilization.
  • Change IDL to 2000 rpm and wait for stabilization.
  • Repeat steps 1–2, gradually increasing Kp until you see “oscillation” of the speed (periodic fluctuations), instability, or other undesirable effects.
  • Take the resulting Kp value and halve it.

Kd settings

Kd limits the rate of speed drop after reducing the air/fuel supply. It has less impact on idle stability, but if set incorrectly, it can cause rocking.

Tips:

  • The default setting is Kd = 0.
  • If you want to smooth out the drop in RPM when releasing the throttle, increase Kd until you notice an oscillation when releasing the accelerator.
  • Once you notice a oscillation, reduce the Kd value by half.