Guide
Driveability files explained
Driveability files change how the car behaves day to day rather than how much power it makes. This guide covers the four driveability services, what each changes, and what to check first.
Swirl flaps off
Pricing: Master file price €24 ex VAT · slave (Tier E) €14.
Many diesel engines have swirl flaps in the intake that improve air motion at low load. When a flap or its actuator fails, the ECU logs a fault and can limit the engine.
The swirl flaps off file stops the ECU expecting the flaps to move. It is a driveability calibration for a car whose flaps are removed or disabled. Check the flaps and their linkage first.
Start-stop off
Pricing: Master file price €24 ex VAT · slave (Tier E) €14.
Start-stop switches the engine off at idle to save fuel, and restarts it when you release the brake or touch the clutch.
The start-stop off file keeps the engine running at idle. It suits drivers who find the restarts disruptive. Note that start-stop is also linked to battery and comfort systems, so tell us if the car has an AGM battery or an upgraded battery.
Hot start fix
Pricing: Master file price €31 ex VAT · slave (Tier E) €19.
Some engines are difficult to start when hot, typically after a short stop with the engine warm. The cause is often in fuelling or glow and injection timing targets at high temperature.
The hot start fix is a calibration change for that condition. It does not repair a failing starter, a weak battery or a faulty sensor. Rule those out first, because they cause similar symptoms.
Results vary by engine, fuel, condition and supporting hardware, and no gain or outcome is guaranteed.
Vmax and speed limiter off
Pricing: Master file price €24 ex VAT · slave (Tier E) €14.
The factory speed limiter is a software limit. The Vmax off file changes that limit in the calibration.
Speed limits are a legal matter on public roads in many countries, and tyres, brakes and cooling are rated for the factory speed. Only order this for use where it is lawful, such as a closed circuit or a track.
What to send for any driveability file
- Your original read, with the ECU part number and the engine code.
- Any existing fault codes, read before you change anything.
- The vehicle's use: road, track, towing or off-road.
Questions about driveability files explained
Will a driveability file cure a fault?
No. These files change behaviour. A failed component still needs repair. Read the codes first.
Can I combine driveability files?
Yes, where the calibrations do not conflict. Tell us what you want and we confirm the combination before you pay.
See emissions-related files All questions
Emissions-related files are supplied for off-road, competition, agricultural and export use only, and must not be used on public roads.