The Boost Control function is used to regulate boost pressure by controlling the duty of a boost control solenoid. This in turn regulates the air pressure supplied to the wastegate diaphragm.
Note: Due to the large number of pressure units, all default values are quoted in the default unit of kPa.
Mode
Select from using Open Loop or Closed Loop Boost control (Default = Closed Loop)
Open Loop - Open Loop does not use a Target, rather it is a raw amount of duty that the user commands and boost level is tuned by varying this duty.
Closed Loop - Closed Loop Boost Control uses a Target Pressure that the Boost Control system will try to achieve by adjusting duty up or down.
Controlled Parameter
Manifold Pressure - This is the most common selection for Controlled Parameter, and should be used most of the time.
Wastegate Pressure - Some specific applications, such as drag racing, will use wastegate pressure control in order to control the boost pressure. This relies on the target pressure being set appropriately for the circumstances, as the control system is no longer looking at Manifold Pressure. Wastegate Pressure is used for CO2 two-solenoid control systems. In order to control the wastegate pressure, a wastegate pressure sensor must be used.
Boost Pressure - Some specific applications will use wastegate pressure control in order to control the boost pressure. A boost pressure sensor must be enabled and configured to set Boost Pressure as the Controlled Parameter.
Output Frequency
The frequency to be used by the Boost Control Solenoid.
Minimum Duty Cycle
The minimum duty that can be commanded by the Boost Control solenoids. This can prevent the boost control from commanding a duty that the solenoid will not react to.
Maximum Duty Cycle
The maximum duty that can be commanded by the Intake Boost Control solenoids. This can prevent the boost control from commanding a duty that the solenoid will not react to.
Control Point Offset
Active only when Closed Loop Mode is selected and Controlled Parameter is Manifold Pressure. The amount of Boost Pressure below the Target Pressure that must be exceeded before closed loop Short Term control of duty will commence. Eg. If the Target Pressure is 200kPa, and the Control Point Offset is 50kPa then Closed Loop control will activate when Boost Pressure exceeds 150kPa. Below this amount it will use the Closed Loop Base Duty Cycle table, or it will be fixed to 100% duty under this amount if the Spool Assist is Enabled. A value that is too low can cause the boost to overshoot the target. A value that is too high can cause Closed Loop to activate while boost pressure is not stable and lead to inconsistent boost control.
Max Derivative
Active only when Closed Loop Mode is selected. The rate at which the Boost Pressure is increasing must be below this amount before closed loop Short Term control can be active. This is to avoid boost control from making changes to the output duty while the boost is still climbing at a high rate and is not stable.
Overboost Offset
Active only when Closed Loop Mode is selected and Controlled Parameter is Manifold Pressure. If the Boost Pressure exceeds the Target Boost by this amount the Duty will be set to 0%. i.e. the controller will disable. This is to try and prevent an overboost condition that may be dangerous to the engine or user.
Enable Spool Assist
Active only when Closed Loop Mode is selected and Controlled Parameter is Manifold Pressure. When Enabled, this will cause the Duty to be 100% while boost pressure is positive and is lower than the Target Pressure minus the Control Point Offset. Eg. If the Target Pressure is 200kPa and the Control Point Offset is 50kPa, when the Boost Pressure is higher than 0kPa and is less than 150kPa the duty is fixed at 100%. This can be used to help build boost faster. When Disabled, the corresponding Closed Loop Base Duty table value will be used instead. In some instances the Spool Assist can cause “spiking” above the target with varying throttle input.
Closed Loop Min TPS
Active only when Closed Loop Mode is selected. The Short Term Trim Minimum TPS is the amount of throttle opening that must be exceeded before closed loop Short Term control can activate. This is to prevent the controller from making adjustments while the boost is not stable. Eg. if the throttle opening is low and is holding back the boost from reaching target, the controller would increase the boost duty to try and make the boost reach target. If the throttle is then opened to 100% this will cause the boost to overshoot the target. The STT Min TPS is used to prevent this occurring by only allowing corrections to be made while the boost is able to actually reach the target.
Boost Trim Enable - Enables a function where an external Trim Module can be used to driver adjustment of boost.
Trim Max - When the Mode is set to Closed Loop this is the maximum amount of boost target pressure reduction allowed by the external Trim. When the Mode is set to Open Loop this is the maximum percentage amount of reduction of the duty cycle allowed by the external Trim.
Scramble Boost Enable - Enables a function where a timed amount of extra boost is allowed via a selected input request to the Elite ECU.
Target Offset - Active only when the Mode is set to Closed Loop. This is the amount of extra boost pressure to be added onto the Target Pressure while the Scramble Boost function is active.
Base Offset - The amount of extra duty cycle to be added to the boost control duty cycle while the Scramble Boost function is active. When the Mode is set to Closed Loop this value should be “0” and the Closed Loop Base Duty Cycle table should be set accordingly for the extra target pressure that is to be added.
Hold Time - Additional boost is applied as soon as the Scramble Boost button is pressed but will remain active for this amount of time after the Scramble Boost button is released.
Max Time - The maximum total amount of time that the Scramble Boost can be applied.
Rest Time - The minimum time allowed between scramble boost events.