Cyclic Idle is used to limit the engine speed when the throttle is released, Anti-Lag is inactive and excessive air is still being bled into the engine. Cyclic idle is necessary in a situation where motor sport rules do not allow the fitting of an ECU controlled extra air bleed solenoid to the vehicle which results in a permanent excess of air which would otherwise cause excessively high idle speed. Cyclic Idle cuts fuel to the engine to maintain a steady, usable idle speed.
To monitor the status of the Anti-Lag System see the MotorSport tab of the Runtime Values window (F12 Key). For detailed information on how the limiting and cutting system works see Limiting System.
Safety Note
When in Cyclic Idle Mode a 100% fuel cut will be applied if the engine speed exceeds the Cyclic Idle RPM Limit by more than 500RPM. This is not adjustable but is a safety feature in the event that the Cyclic Idle system is setup incorrectly.
Cyclic Idle Setup Notes
·The difference between Cyclic Idle High and Cyclic Idle Low is normally 3 to 5%.
·The Cyclic Idle Low and Cyclic Idle High numbers MUST be bigger than the position the throttle is at when cyclic idle is running. For example, if you have the throttle open 20% at idle, then these must be bigger (e.g 22% and 26%).
·The RPM limit for the engine is dependent on the throttle position and the Cyclic Idle High and Cyclic Idle Low settings:
·When throttle position is less than the Cyclic Idle Low setting, the RPM limit is the cyclic idle limit.
·When throttle position is greater than the Cyclic Idle High setting, the RPM limit is the current engine RPM limit.
·When throttle position is between the Cyclic Idle Low and Cyclic Idle High settings, the RPM limit is interpolated between the cyclic idle limit and normal RPM limit. For example, when throttle position is half way between the low and high settings, the current RPM limit is half way between the cyclic and normal RPM limits. This allows the engine to transition gently into normal running after being on cyclic idle.
·Cyclic idle is active only when the Anti-Lag System Arming control option is active. This means that if you want a setup with cyclic idle, but without Anti-lag you need to make the Anti-lag system in-active. This can be done by putting zero in the tables and setting the arming values to very high numbers.
Note: Cyclic idle Limiting will not operate correctly if the standard RPM Limit has not been set up.
This is the master control of cyclic idle. The following modes are available:
·OFF - Cyclic idle never operates
·Always ON - Cyclic idle is always ON, regardless of whether anti-lag is Armed or OFF(from DI control).
·Cool Down - Cyclic idle only operates for a set time after anti-lag transitions from active to armed.
·ON = System Armed - Cyclic idle is active only when anti-lag is armed.
Idle speed will be controlled at the Cyclic Idle Limit RPM while the throttle position (TP(Main)) is BELOW this value. At throttle positions between this value and the Cyclic Idle High value, cyclic idle will be progressively decreased to allow for a smooth transition to normal running. This value should be set to about 2% above the closed throttle position (with the throttle stop screw holding the throttle plate opened).
When throttle position (TP(Main)) is above this value, the cyclic idle limit will be disabled. This value should be set to approximately 5-10% higher than the Cyclic Low value.
The following image shows a graphical representation of how Cyclic Idle Low, Cyclic Idle High and Cyclic Idle Limit interact. These settings aim to provide a smooth reentry into driving from cyclic idle.
This is the actual idle speed that the cyclic idle limit will operate at when throttle position (TP(Main)) is BELOW the Cyclic Idle Low value. A typical value for this would be 1800RPM.
This table overrides the current position of the idle speed (solenoid, stepper motor or ethrottle). This override is used to bleed extra air into the engine while Cyclic Idle is active. A standard Idle valve does generally not flow enough air for proper Cyclic Idle operation, an after market upgrade is often necessary. This override is only available when Idle Speed Control is setup and will override ISC's Min and Max Clamps. Note: A separate ISC Override Table is provided for Anti-Lag.
Note: The ISC Override function will only be visible if ISC Override if set to ON AND Idle Speed Control Mode is not Off.
Controls the length of time the cyclic idle will remain ON for, when the Anti-Lag switches from ON to OFF. This setting only applies when the Cyclic Idle Mode is set to Cool Down mode.
Advanced mode allows more control over the cyclic idle RPM limiting cut method. When set to OFF, the ECU will use default cut settings. If the advanced mode is set to ON, the following settings will become available:
·Limit range
·Cut effect
·Start cut
·End cut
This setting is only available when Advanced Mode is set to ON.
The engine speed (RPM) range which the limiting control will operate over. The range is in addition to the Cyclic Idle Limit. A typical value for this would be 200RPM. (Hint - to create a more aggressive sounding cyclic idle, decrease this number).
This setting is only available when Advanced Mode is set to ON.
The Cut Effect controls the method that the ECU uses to perform the cyclic fuel cut. The following options are available:
·Adaptive - the ECU will apply an adaptive cut pattern based on the current engine speed.
·Constant - the ECU will apply a constant cut pattern based on the current engine speed.
This setting is only available when Advanced Mode is set to ON.
The start cut determines the percentage ignition cut applied at the start of the Limit Range. A typical value would be 30%. The Start Cut RPM is the Cyclic Idle Limit.
This setting is only available when Advanced Mode is set to ON.
The end cut determines the percentage ignition cut applied at the end of the Limit Range. A typical value would be 90%. The End Cut RPM is found by adding the Limit Range to the Cyclic Idle Limit.
See Also:
·Anti-Lag Runtimes - A list of the Antilag Runtime Values/Statuses and what they mean