What it is for
Normally a Nexus nitrous stage only turns on when its activation conditions and mode say so. An override skips those rules and turns the stage on anyway. Two jobs account for almost every use:
- Purging. Before a run, you briefly open the system to push air and gaseous nitrous out of the feed line, so liquid nitrous is right at the solenoid when the stage comes in. Racers call this "burping" the system.
- Manual activation. Some drivers want a button on the wheel that fires the stage when they decide, rather than when the ECU's conditions line up.
The safety gates
Even an override has to pass a few basic checks before it will work:
| Setting | What it requires | Why it matters |
|---|---|---|
| Minimum Engine Running Time | The engine has run at least this long | Stops the override firing during or right after startup |
| Minimum TPS | Throttle at or above this position | Prevents a stage firing with the throttle closed |
| Minimum RPM | Engine speed at or above this | Keeps nitrous out of very low RPM where it is hardest on the engine |
A purge usually happens with the car stationary and the engine idling. If your override is meant for purging, think carefully about how your TPS and RPM minimums interact with that. Remember the override turns on the whole stage, so set the gates too tight and it never works when you need it, too loose and the stage comes on when you did not mean it to.
Switch or conditions
There are two ways to trigger the override, and they can be used separately or together:
- Switch Enable assigns an input pin, so a physical button or switch triggers the override.
- Conditional Activation uses ECU channel conditions instead, or as well as the switch. If you turn Switch Enable off, this is how you trigger it.
Combining the two is a good way to make a button that only works in the right circumstances, for example only when an arming switch is on.
Before you use it
- Set up the stage itself in Nitrous Controller and its activation rules in Nitrous Enable.
- Wire the button using the enable wiring notes, and the solenoids per controller wiring.
- Consider a nitrous pressure sensor so you can see in the log that a purge really brought pressure up.
- Test the override with the bottle closed first, and confirm in the log that the stage only activates when you expect it to.
New to ECU-controlled nitrous? Start with ECU controlled nitrous injection.
