What an enabler does
On an Elite ECU, nitrous is split into stages, and every stage answers to an enabler. The enabler doesn't spray anything on its own. It decides whether the stages assigned to it are allowed to activate. Turn the enabler off and those stages are locked out no matter what else is going on.
You can configure up to four enablers and assign stages however suits the car. A simple street setup might put everything under one arming switch. A drag car might give a single enabler to the first stage and a separate one to the later stages, so the driver can arm the extra power only when conditions allow.
Switch or conditions?
In the Wiring tab, Switch Enable decides whether a physical input controls the enabler.
- Ticked: an input pin arms and disarms it.
- Unticked: you use Conditional Activation on the Settings tab instead.
Conditions can also be combined with a switch, which is how we set up most cars. The driver arms the system with a switch, and the ECU still refuses to enable it unless, for example, coolant temperature, RPM or throttle are where you want them.
Wiring the arming switch
The switch can go to an SPI or an AVI.
On an SPI
| Setting | What it controls | Our advice |
|---|---|---|
| Edge Select | Which direction of change means "on" | Falling if the switch grounds the input; Rising if the switch feeds it voltage |
| Sensor Type | How the input conditions the signal | Hall Effect for any switch input |
| Pullup | Holds the input at a voltage when the switch is open | Turn it on for a ground-switching switch so the input doesn't float |
On an AVI
An AVI reads a voltage, so you tell the ECU where "on" and "off" are with two thresholds: Switch On Voltage and Switch Off Voltage. Leaving a gap between them gives you hysteresis, so electrical noise or a sagging battery can't flick the enabler on and off.
A couple of examples in our own words:
- Switch to ground. The input rests near 5V and drops to near 0V when switched. Set on to about 0.5V and off to about 4.5V. It arms when the voltage falls below 0.5V and disarms once it climbs back above 4.5V.
- Switch to 12V. The input idles around 2.5V and rises to battery voltage when switched. Set on to about 4.5V and off to about 3.0V. It arms above 4.5V and disarms below 3.0V.
The exact figures depend on your circuit. Measure the real resting and switched voltages in ESP first, then put the thresholds comfortably inside that range.
Wire the arming switch so that a broken wire or unplugged connector leaves nitrous disabled. With a switch to ground and the pull-up on, an open circuit reads as "off," which is what you want.
Troubleshooting
| Symptom | Usually |
|---|---|
| Enabler never turns on | Wrong edge selected, or AVI thresholds outside the voltages the switch actually produces |
| Enabler flickers | No gap between on and off voltages, or the SPI input floating without a pull-up |
| Switch is on but stage stays off | A Conditional Activation condition isn't met, or the stage is assigned to a different enabler |
Related nitrous setup
Enablers are one piece of the nitrous system. Configure the stages themselves in nitrous stages, add safety overrides with nitrous overrides, and see the big picture in nitrous control. For solenoid wiring, our multistage relay wiring page helps. Bottle pressure feedback comes from a sensor like the 2000 psi nitrous pressure sensor.
How many enablers do I need?
One is enough for most single-stage kits. Use more when you want separate arming for different stages.
Can I arm nitrous without a switch?
Yes. Untick Switch Enable and rely on Conditional Activation, though we like a physical switch the driver controls.
