How RPM Drop detection works
Every upshift causes a sudden fall in engine speed. RPM Drop detection counts those falls. The ECU starts in first gear, and each time RPM climbs past a setpoint and then drops by a set amount, it adds one to the gear number. It's simple and needs no extra sensors, which makes it popular in drag cars where shifts are always sequential and full throttle.
This node only appears when the Gear Detection Type is set to RPM Drop in gear detection.
The settings
| Setting | What it does |
|---|---|
| First to Fifth Gear Setpoint | The RPM the engine must pass in that gear before the ECU starts watching for a drop |
| First to Fifth Gear Drop | How far RPM must fall after passing the setpoint to count as a shift to the next gear |
| Gear Reset RPM | If RPM falls below this, the gear is reset to first |
| Gear RPM Drop Reset Time | How long RPM must stay under the reset RPM before the reset happens |
Setting it up
- Use logs of real shifts. Note the RPM you shift at and how far it falls in each gear.
- Set each setpoint a little below the shift RPM, and each drop a little smaller than the logged fall, so every shift is counted.
- Keep the drop large enough that a lift, a missed shift or wheelspin can't be mistaken for a gear change.
- Choose a reset RPM and time that clearly mean the run is over, such as returning to idle.
If you have a gear position sensor, gear position or a gear switch will be more reliable on the street.
