What the ECU takes over
A traditional nitrous setup is a handful of switches, a window switch and a lot of trust. With Haltech's nitrous control on an Elite, the ECU decides when each stage turns on, and it applies the fuel and ignition changes that stage needs at the same moment. It supports both wet kits, which add fuel through a nozzle, and dry kits, where the injectors supply the extra fuel. You can run up to six stages.
A stage only fires when two sets of rules agree: the safe operating conditions you set are met, and its activation condition is met. That's what makes an ECU-controlled system safer than a pile of switches. For the bigger picture, see ECU-controlled nitrous injection.
The pieces of the function
| Part | What it's for |
|---|---|
| Nitrous Enablers | A master switch per stage. With the enable off, the stage stays off, so you don't burn through a bottle cruising around |
| Nitrous Overrides | An input that forces activation, used either as a purge button or as a manual "spray now" button |
| Nitrous Pressure Sensor | Reads bottle pressure, for logging and for safety conditions. The 2000 psi brake/nitrous pressure sensor suits this |
| Nitrous Stages | Where each stage's outputs, conditions and corrections are set up |
The tables that appear in the ECU Navigator
Which tables show up depends on the options you tick for each stage. Each one only applies while that stage is active.
| Table | Shows when | What goes in it | Our advice |
|---|---|---|---|
| Overall Ignition Correction | 'Ignition Correction' is checked | A negative timing change for the stage's assigned bank(s). Axes are editable up to 16x16 | Pull timing first, add it back only with evidence from plugs and knock data |
| Cylinder Ignition Correction | 'Cylinder Ignition Correction' is checked | Per-cylinder trims from -10 to +10 degrees, on top of the overall correction if used | Use it for the cylinders your nozzle layout or plugs say run hotter |
| Overall Fuel Correction | 'Fuel Correction' is checked | Extra fuel delivered through the injectors to the assigned bank(s). Up to 16x16 | This is how a dry kit gets its fuel. On a wet kit, it's for trimming, not the main supply |
| Target AFR Correction | 'AFR Correction' is checked | A negative change to the AFR target, making the target richer. Up to 16x16 | Keeps closed loop fueling from fighting the richer mixture nitrous needs |
| Activation | The stage's activation mode is Race Timer or Vehicle Speed | An 8x1 table giving the time or speed at which the stage turns on | See below |
Activation by time or speed
For drag cars, it's common to bring stages in progressively rather than all at once. The Activation table handles that:
- In Race Timer mode, it sets how long into the run the stage turns on, using the race timer.
- In Vehicle Speed mode, it sets the road speed at which the stage turns on, which needs a working vehicle speed sensor.
One detail to know: a value of 0 means "off." A 0.000 s time or a 0 speed stops the stage activating, and if you step into a 0 cell after the stage came on earlier, it switches the stage off. That makes it easy to build a window where a stage runs and then drops out.
Hardware changes mean tune changes
Changing the bottle, a solenoid or a jet changes how much nitrous actually reaches the engine. Every one of those changes needs matching changes to that stage's fuel and ignition corrections. Get it wrong and the engine can go lean or detonate, fast.
Bottle pressure has the same effect, which is why logging it is so valuable. For wiring multiple stages through relays, see multistage nitrous relay wiring.
FAQ
Can I run a wet kit and still use the ECU's fuel correction?
Yes. Most of the fuel comes from the wet nozzle, and the ECU correction trims the result.
Why won't my stage activate?
Check the enable switch first, then the safe operating conditions, then the Activation table for zeros.
Where do I start with timing?
Conservative, with a clear plan to confirm in logs and on the plugs. If you want it done right, talk to us.
