What the Air Pump function does
The Air Pump function switches an air pump on and off from an Elite output, based on RPM, load, deceleration and idle stability. An air pump puts a real electrical and mechanical load on the engine, so the function is built to keep it off when that load would upset the engine, such as right after start-up or at high load.
Wiring tab
- Air Pump Output: the output driving the pump, usually through a relay. A DPO (digital pulsed output) is the typical choice, and a stepper output can also be used.
- Active State: sets the output polarity. Low (the default) grounds the wire when the pump should run. High inverts it, grounding the wire when the pump should be off and releasing it when it should run.
A pump draws far more current than an ECU output can supply, so run it through a relay like the 30A 5-pin power relay, with the ECU switching the relay coil.
Air Pump tab
| Setting | What it does | Our advice |
|---|---|---|
| Disable Air Pump on Decel | When ticked, the pump shuts off while the car is decelerating | Usually worth ticking |
| Idle Delay | Time allowed for idle to settle before the pump adds its load | Long enough that idle is stable in your logs before the pump kicks in |
| Hysteresis | A time delay between the enable conditions being met and the pump turning on | Enough to stop the pump cycling when conditions hover at a limit |
| Min RPM | The pump won't run below this RPM | Set to suit your idle and the pump's purpose |
| Max RPM | Above this RPM the pump is switched off | Keep it inside the range where you actually want it working |
| Max Load | Above this load the pump is switched off | Keeps the pump from running under heavy load |
Note that the Hysteresis setting here is time based, not an RPM or load band. The conditions have to stay true for that long before the pump starts, which smooths out short blips.
Setting it up
- Assign the output, confirm the active state with an output test, and make sure you hear the relay click and the pump run.
- Set Min RPM, Max RPM and Max Load to frame when the pump is allowed to run.
- Add an idle delay and watch idle in your logs as the pump engages. If RPM dips hard, lengthen the delay or check idle control.
- Tick Disable on Decel unless you have a specific reason to run it on overrun.
Troubleshooting
| Symptom | Usually |
|---|---|
| Pump never runs | Wrong output, active state reversed, relay not powered, or limits set so conditions are never met |
| Pump runs all the time | Active state inverted for your wiring |
| Idle dips when the pump starts | Idle Delay too short or idle control not compensating |
| Pump cycles on and off | Hysteresis too short, or conditions hovering at a limit |
Other simple output functions set up the same way include Dual Intake Runner and Reverse Lockout.
