What overboost cut is for
Boost control keeps boost where you want it. Overboost cut is what happens when that fails. A split wastegate hose, a stuck solenoid or a sticking wastegate can send boost well past target in seconds. Once enabled, the Elite watches boost and, if it stays above your limit long enough, cuts power until pressure drops.
Enabling the function adds an Overboost Cut section to the ECU Navigator with the Cut Pressure table.
Settings
All pressures default to kPa. Change units in ESP if you prefer psi.
| Setting | What it does | Our advice |
|---|---|---|
| Cut Method | Ignition, Fuel, or Fuel & Ignition | Ignition is the common choice and reacts quickly |
| Cut Pressure | The boost limit, mappable up to 2D. Default 150 kPa | Safely above your highest target, safely below what the engine can survive |
| Delay | How long boost must stay over the limit before cutting. Default 0.50 s | Long enough to ignore a momentary spike, short enough to stop real overboost |
| Hysteresis | How far boost must fall below the limit before power returns. Default 10 kPa | Prevents rapid on-off cutting right at the limit |
How the numbers work together
Here is an example of our own. Say you target 22 psi and set Cut Pressure to 26 psi, Delay to 0.3 s and Hysteresis to 2 psi. A quick flicker to 27 psi that falls back in a tenth of a second is ignored. If a wastegate hose splits and boost sits at 27 psi, the Elite cuts after 0.3 s and keeps cutting until boost falls below 24 psi. Because Cut Pressure can be a 2D table, you can also run a lower limit in lower gears or at lower RPM.
Don't use overboost cut to set your boost level. Repeated cuts under boost are hard on the engine and drivetrain. If it is triggering regularly, fix the boost control, not the limit.
Which cut method?
- Ignition: the usual choice. Fast and effective.
- Fuel: useful where ignition cut causes problems with your exhaust or setup, but be careful of lean cylinders while cutting.
- Fuel & Ignition: cuts both for the strongest power reduction.
Pair this with properly tuned Elite boost control, and read our boost control user's guide for the closed loop side. If you measure boost on a separate sensor, see boost pressure sensor. For the full picture on protection, see don't blow your engine.
