What it does
The Pit Lane Speed Limiter caps vehicle speed, not just engine speed. You set a road speed, and the Nexus converts it into an engine speed limit, then uses an ignition or fuel cut to hold the engine there. On a drive-by-wire car it can also cap how far the throttle opens, which makes the limit much smoother.
It's built for pit lanes with speed limits, and for the road sections between stages in events like rally, where you're driving on public roads with a race car.
The settings
| Setting | What it does | Our advice |
|---|---|---|
| Cut Method: Ignition | Cuts spark while the car is at or above the limit, until speed falls back below it | Our usual choice; response is quick and it's easy on the fuel system |
| Cut Method: Injection | Cuts fuel instead, on the same rules | Useful where ignition cut is harsh on the exhaust or catalyst; watch for lean spikes on re-entry |
| Speed Limit | The road speed you want to hold | Set it a little under the posted limit to allow for speedo and sensor tolerance |
| Speed Lock-Out | Stops the limiter from switching on above this speed | Set it comfortably above pit speed so a mis-press at race pace does nothing |
Why the lock-out matters
Without a lock-out, bumping the pit button at full speed would hit the car with a sudden cut. The lock-out makes the button ignored until the car is already slow, so the only time it can engage is when the driver is really entering the pits.
Speed sensor redundancy
The limiter uses the fastest of the available vehicle speed readings. If one sensor fails, it falls back on another, so a dead wheel speed sensor won't stop the limiter from working. Make sure your vehicle speed sensors are set up and reading correctly first.
Making it smooth
A plain cut works, but it can feel jerky. The Nexus gives you three extra tools to smooth it out:
- DBW throttle max: caps throttle opening on DBW cars so the engine barely needs cutting.
- Ignition correction: pulls timing to soften power near the limit.
- Fuel correction: adjusts fueling while the limiter is active.
Wiring the button is covered in Pit Lane Speed Limiter Wiring.
Try it in a safe place and check the car settles at the right speed in the gear you'll use for the pit lane. Log vehicle speed against the limit to confirm.
