Why measure turbo speed?
Every compressor wheel has a maximum safe shaft speed. Push past it, whether from chasing boost at altitude, running a small turbo too hard, or a boost control fault, and the wheel and bearings pay for it. A turbo speed sensor reads the compressor blades as they pass and gives you the actual shaft rpm, so you can see how close to the limit you're running instead of guessing from boost and airflow. The Elite supports two, so twin-turbo setups can watch each side.
Setting it up
Wiring tab
Assign the sensor to a synchronized pulsed input (SPI). It's a frequency signal, so an SPI is the right input.
| Setting | What it does | Our advice |
|---|---|---|
| Edge Select | Which edge of each pulse the ECU counts | Falling, unless your sensor's instructions say otherwise |
| Sensor Type | Digital Hall effect or reluctor | Match the sensor you've fitted, per its instructions |
| Pull Up | Gives an open-output Hall sensor a voltage to switch | Turn it on only if the sensor or its wiring doesn't already provide one |
Calibration tab: Number of Blades
Enter how many blades are on the compressor wheel. The ECU uses this to turn pulses into shaft rpm. This setting assumes the sensor's electronics send one pulse for every eight blades that pass, which is how common aftermarket turbo speed kits work. If your sensor is different, the reading will be off by a fixed ratio.
Don't guess the blade count. Check the turbo or sensor manufacturer's data for your exact compressor wheel, because a wrong count throws every reading off.
Display tab: Warning Maximum
Set the shaft rpm that should worry you. Above it, turbo speed gauges in ESP flash red. This is a visual warning only. We set it a sensible margin below the manufacturer's maximum rated speed, so it catches you before you reach the limit rather than after.
Diagnostics tab: Raw Max
Raw Max is off by default. When enabled, the ECU sets fault code P2581 if the input voltage rises above your limit, which points to a short or disconnected wire. With the Engine Protection function running, you can also give that fault a DTC severity level.
Log turbo speed next to boost, rpm and boost control duty. If shaft speed keeps climbing near the warning limit while boost holds steady, the turbo is being overworked, often from thin air at altitude or a boost target that's too ambitious for the turbo.
Turbo speed FAQ
My turbo speed reading looks wrong. Why?
Usually the blade count is wrong, or the sensor doesn't use the divide-by-eight output the calibration assumes. Check both before anything else.
Does the Elite cut boost if the turbo overspeeds?
The Warning Maximum is a display warning. For protection, talk to us about building turbo speed into your boost strategy.
