MHD Tuning Guide

MHD Flasher turns your phone into a full tuning tool for your BMW or Toyota Supra: flash off-the-shelf or custom maps, switch maps in seconds, datalog, read and clear codes, and go back to stock at any time. This guide walks you through the whole process in plain English, from buying the right license to your first flash. Each section links to the matching page of MHD's own documentation for the full detail.

1. Quick-start checklist

1. Buy the MHD license for your engine (see the table below). Give us your MHD account e-mail and your VIN at checkout.
2. Get a supported connection: the MHD Universal WiFi adapter is the easiest option.
3. Install the MHD Flasher app for your engine and log in.
4. Connect to the car once so MHD can read the VIN.
5. Activate the license key we e-mail you (usually within 12 hours).
6. Check whether your DME needs an unlock.
7. Put a battery charger on the car and flash your first map.

2. Pick the right license

MHD licenses are sold per engine and are locked to one car (VIN) and one MHD account. The Super License includes the Flasher, the Monitor (datalogging) and the off-the-shelf maps for that engine.

MHD's full list: Supported Vehicles · Unsupported vehicles

3. Hardware you need

• A phone or tablet: Apple iOS 10.2 or newer, or Android 6 or newer.
• A connection to the car. We recommend the MHD Universal WiFi adapter: it plugs into the OBD-II port, works with iOS and Android, and gives the fastest flash times. MHD also supports an ENET cable with a Lightning adapter (iOS), and on some engines a K+DCAN cable with an OTG adapter (Android) — check your license page. MHD does not support third-party adapters.
• A battery charger or maintainer. Strongly recommended for the first install, for returning to stock and for any long write.

More detail: MHD Hardware Requirements

4. Install the app and log in

• Download the MHD Flasher app for your engine from the App Store or Google Play. There are separate apps for the E-series N54, the E-series N55 and the F / G-series cars, so pick the one that matches your car.
• On Android, allow the file permission the app asks for on first launch; it uses it to save logs and tunes.
• Open the menu (☰) and choose MHD Login. You can sign in with Apple, Google or Facebook, or create an MHD account (new accounts need e-mail verification). On Android, Google Chrome must be installed for the login to work.

More detail: MHD Getting Started

5. Connect to your car

1. Plug the MHD WiFi adapter into the OBD-II port under the dash and give it a few seconds.
2. On your phone, join the WiFi network named MHD_ followed by a code.
3. Switch the ignition on (or start the engine) and open the MHD app.
4. Test the connection: open the Codes tab and tap Read DME Codes. If codes (or "no codes") come back, you are connected.

More detail: MHD Connecting to Car

6. Activate your license

1. Connect to the car at least once first, so MHD can read the VIN. If you have more than one car, connect to the one the license is for.
2. Find the license key in the e-mail we send you after your order (usually within 12 hours of payment; check spam and promotions folders).
3. In the app: ☰ menu > My Licences > Activate License Key, enter the key and press OK. Repeat for each key.

Licenses are non-refundable and are bound to one VIN and one MHD account; a different car or account needs a new license.

7. Does your DME need an unlock?

Newer BMW software blocks flashing over the OBD port until the DME is unlocked. The MHD app has an Unlock Check that tells you whether your car needs one. As a rule of thumb from MHD:

• Many earlier cars with their original software flash without an unlock.
• Cars with the newest BMW software need a DME bench unlock.
• B58 Gen 2 cars built before 06/2020 always need a bench unlock.
• Cars built after 06/2020 need a special unlock (FEMTO or AutoTuner), which keeps full MHD+ support.

Once the DME is unlocked, MHD detects it automatically. Speed Logic offers DME unlock services — for B58 cars see our ECU Unlock Service, or contact us for other engines.

8. Flash a map

You have three choices: an MHD off-the-shelf (OTS) map, a custom map from your tuner, or Stage 0 (stock power with MHD installed so you can still use flash options and logging).

• Pick the stage that matches your parts. Stage 1 is for stock cars; Stage 2 needs the hardware listed for it (usually a high-flow downpipe and, on some engines, no particulate filter). Pick the octane that matches the fuel in your tank. The exact maps and requirements for your engine are on your license page.
• Choose your flash options (burble, cold start, exhaust flap, top speed limiter and so on — the list depends on the engine).
• The first install is a long write and takes a few minutes; after that, switching maps is a short write of seconds. Keep the battery charger connected for every long write.

More detail: MHD Flashing your Car (includes OTS maps, custom tunes and flash options)

9. Return to stock

• Flash back to stock (Stock menu) removes MHD and puts the DME back to factory. You don't need a backup — MHD rebuilds the original file from the car. Do this before you sell the car. It is a long write, so use a battery charger.
• Flash Stage 0 gives you stock power while keeping MHD installed — handy for troubleshooting.

More detail: MHD Return to Stock

10. Datalogging

• Open Mon > Data Logging. Start and stop logging by hand, or turn on automatic logging so it starts when you pass a set throttle position.
• Up to 8 gauges show on screen, and many more parameters can be recorded. Choose them in Monitor Options.
• Logs are saved as CSV files. View them with Mon > Graph a Log; swipe left on a log to rename, share or delete it.
• Rename logs with a short note (fuel, map, what you noticed) so they are easy to find.

More detail: MHD Data Logging

11. Codes and adaptations

• Read DME codes from the Codes tab, and clear them once the cause is fixed.
• Reset adaptations clears what the engine has learned — useful after fitting new parts or changing tunes, so the DME relearns cleanly.

More detail: MHD Read DME Codes · MHD Reset Adaptations

12. MHD+ features

MHD+ is MHD's custom code, included with the Super License on supported engines. Depending on your engine it adds on-the-fly map switching (with a power-level slider), antilag, burble settings per map slot, on-the-fly exhaust flap control, an ethanol content readout, Motiv ReFlex port-injection integration and more. Each license page lists exactly what your engine gets.

More detail: MHD+ Suite · JB4 users: MHD backend flash + JB4 flowchart

13. FlexFuel

With an ethanol content analyzer fitted, MHD's FlexFuel maps adjust the tune to whatever ethanol blend is in the tank. Turn the FlexFuel option on in the app after installing the kit (how-to video).

• MHD FlexFuel Kit (Automatic) – F-Series
• MHD FlexFuel Kit (Automatic) – G-Series / Supra
• MHD FlexFuel Kit (Open Wire) — manual-transmission cars, all N54 and E-series N55

14. FAQ

Can I move my license to another car?

No. A license is bound to one VIN and one MHD account. A different car needs its own license.

My licenses disappeared from the app.

You are most likely logged in with a different method than the one you used to activate them. Log out and log back in the original way.

Do I need an initial backup before flashing?

No. MHD can rebuild the factory file and return the car to stock at any time.

Which adapter should I buy?

The MHD Universal WiFi adapter. It works with every MHD app, on iOS and Android, and is the fastest option.

Is this street legal?

MHD tunes are sold for off-road use only.

More answers: MHD FAQ

15. Full MHD documentation

This page is Speed Logic's summary. MHD's own user guide is the complete reference and is kept up to date by MHD: MHD User Guide · MHD instructions · MHD Community