Requires an output to be activated as Boost solenoid (closed loop)
Closed-loop boost operates in up to four stages depending on current conditions:
Stage 0 – Disabled
Regulation is off. This occurs if the engine isn't running, target boost is zero, external input disables control, or meth injection forces low boost.
Stage 1 – Spool-Up
MAP is well below target (by more than spool threshold).
The ECU commands maximum solenoid duty to spool the turbo quickly.
No PID regulation is active.
Stage 2 – Approaching Target
Boost is rising and within spool threshold but not yet close to target (based on control threshold).
Open-loop duty from the boost duty table is used.
PID is partially active: only D-term is applied to avoid overshooting.
Stage 3 – Closed-Loop Active
Boost is near target.
Full PID control is active (P, I, and optionally D).
This stage ensures precise and stable regulation.
The system transitions automatically between stages based on MAP and target boost levels.
Note: The current boost control stage (0–3) is shown in the RealTime Value Boost stage parameter. This helps visualize and diagnose what part of the regulation logic is currently active.
closed loop boost, PID settings
mode
•Open loop (base table tuning) - No closed loop is active, used to first tune the open loop duty tables.
•closed loop - Closed loop control is active.
•closed loop (wastegate back pressure control) - Closed loop control is active as wastegate back pressure control.
Important: Always start with Open loop (base table tuning) mode.
Do not activate Closed Loop control until the base boost duty table is properly tuned!
activation
active above map
This setting defines the minimum MAP (manifold absolute pressure) required before closed-loop boost control becomes active.
If the current MAP is below this threshold, the system will stay in Stage 0 (off) or Stage 1 (open-loop max duty during spool).
Once the MAP exceeds this value and the boost target is also above this threshold, closed-loop control (Stage 2 or 3) is allowed to engage.
This helps prevent early boost regulation during low load or idle conditions.
If “Baro corrected” is enabled, the activation threshold is adjusted based on barometric pressure to maintain consistent activation behavior at different altitudes.
active above map mode
This setting determines how the Active Above MAP threshold (in kPa) is applied:
•Absolute map - The threshold is used as-is, based on raw manifold pressure (MAP).
•baro corrected - The threshold is adjusted by subtracting the current barometric pressure. Example: If the threshold is set to 120kPa and barometric pressure is 95kPa, the effective activation point will be 115kPa.
This allows consistent boost activation behavior regardless of altitude or weather conditions.
PID
Closed-loop boost control uses a PID regulator to adjust solenoid duty based on the difference between target and actual boost (MAP).
PID as tables
Instead of using fixed gains, the PID controller can optionally use 3D tables for dynamic adjustment:
P Gain Table: Sets proportional gain based on configurable axis (e.g., RPM, throttle, etc.).
I Gain Table: Controls the integral response, active only in Stage 3.
D Gain Table: Defines derivative gain, active in Stage 2 or when using backpressure control.
This allows the PID behavior to adapt to varying engine conditions, improving regulation across the full operating range.
P Gain (Proportional)
Reacts to the current error (target - actual).
A higher P gain increases response speed but may cause overshoot or instability.
I Gain (Integral)
Integrates the error over time to eliminate steady-state offset.
Only active in Stage 3 (precise control).
High I gain improves accuracy but may cause oscillations if too aggressive.
D Gain (Derivative)
Reacts to how fast the error is changing.
Used mainly in Stage 2 (boost still ramping) or with backpressure control.
Helps dampen response and prevent overshoot.
Each term contributes to the final duty value sent to the solenoid, ensuring fast and accurate control of boost pressure.
I limiter
I limiter
The I limiter restricts how much the integral term (I-term) is allowed to accumulate, preventing excessive buildup (wind-up) that could cause overshoot or slow recovery.
•disabled - The I-term is only limited by the fixed internal value (500), prevents runaway accumulation but does not adapt to boost error. The I-term will integrate freely up to this fixed limit, which may be too aggressive during large boost deviations and cause overshoot or instability.
•enabled, default values - Limits the I-term based on current error size. Larger error --> tighter I-term clamp. 0Kpa error = max 50%, 100kPa error = max 30%, 200kPa error = max 10%. This ensures the I-term is more active near target and less active during large errors.
•enabled, table - Uses a configurable table to define the I-term limit as a function of error or any axis. Allows full tuning control over when and how much integral action is allowed. Table output defines the maximum allowed duty from I-term.
control settings
Deadband
The deadband setting defines a zone around the target boost where the PID controller is inactive. If the error (target − actual) is within the deadband range, no PID correction is applied.
This prevents unnecessary adjustments due to small fluctuations and sensor noise. Helps improve stability and reduces solenoid wear.
Example: If deadband is set to 5kPa, the PID controller will only react when the boost error exceeds ±5kPa.
spooled threshold value
Defines when the engine is considered “spooled” and ready for precise closed-loop boost control.
Allows the ECU to use full open-loop duty during spool-up (Stage 1), and only engage closed-loop regulation when close to the target, improving response time and control stability.
•single value - When the actual boost reaches TARGET BOOST - spooled threshold, the system transitions to full PID control (Stage 3).
•table - Table-based for tuning this threshold based on load, RPM, or other variables.
Control Activation Delay
The Control Activation Delay sets how long the ECU should wait before enabling PID regulation after conditions for closed-loop boost control are met.
The delay timer starts when boost control is ready to activate (e.g., spool complete, MAP above threshold).
During the delay, only open-loop duty is used.
Once the timer expires, Stage 3 (full PID control) is allowed.
This delay helps avoid overreaction during transients, such as gear changes or throttle blips, and ensures stable entry into closed-loop control.
PID control Frequency
Controls how frequently error is evaluated and the solenoid duty is adjusted. Affects how aggressively the system responds to boost changes.
A higher frequency gives faster response but may cause instability or overshooting if gains are too high.
A lower frequency gives smoother regulation but may respond too slowly to fast pressure changes.
Choose a value that balances responsiveness and control stability for your turbo system.
