JB4 Tuner for the BMW B58 — Gen1 & Gen2
The JB4 is the fastest way to wake up a B58 without ever touching the factory ECU. It piggybacks the engine's sensor network over CANbus, so the car makes real power while the DME stays stock — no flash, no VIN lock, no lost warranty flag on an OTA update. Install takes about 20 minutes with hand tools and it comes back off just as easily.
Pick your generation
- Gen1 (2016-2019) — for the earlier B58. A CARB-approved version is available, which is the one you want if the car has to pass a California visual inspection.
- Gen2 (2020+) — for the updated B58 with the revised fuel system.
JB4 or JB4PRO?
Both include the JB4PRO Bluetooth adapter and the free app. Wireless map switching, live gauges, datalogging and firmware updates from your phone are standard either way — the PRO is not "the one with Bluetooth."
The JB4PRO is a different board built for heavily modified cars. On top of everything the standard JB4 does, it adds:
- Direct ethanol sensor control
- Port injection / CPI / WMI control via the PnP add-on harness
- Fuel pressure control for advanced tuning on ethanol mixtures — built in, no upgrade kit needed
- Onboard datalogging memory
- Additional high-current outputs for extra pumps, relays and solenoids
- Additional inputs for monitoring external sensors
- Bluetooth and memory on the board itself rather than via the adapter
- CANbus integration with flash tuning
Running stock or bolt-ons? The standard JB4 is the right call. Building toward E85, port injection or meth? Go PRO. JB4PRO is available on Gen2 cars only.
What it does
- Multiple switchable maps, including E85 blends
- Boost-by-gear so you can pull timing out of 1st and 2nd for traction
- Live gauges, datalogging, fault code read and clear
- Free firmware updates for the life of the unit
- 5-year warranty · designed and assembled in the USA
VEHICLE APPLICATIONS
| Make / Model | Chassis | Engine | Years |
|---|---|---|---|
| BMW M140i | F20 / F21 | B58 Gen1 | 2016–2019 |
| BMW M240i (incl. xDrive) | F22 / F23 | B58 Gen1 | 2016–2021 |
| BMW M240i (incl. xDrive) | G42 | B58 Gen2 | 2022+ |
| BMW 340i (incl. xDrive) | F30 | B58 Gen1 | 2016–2018 |
| BMW M340i (incl. xDrive) | G20 / G21 | B58 Gen2 | 2020–2024 |
| BMW 440i (incl. Gran Coupe, xDrive) | F32 / F33 / F36 | B58 Gen1 | 2016–2020 |
| BMW M440i (incl. Gran Coupe, xDrive) | G22 / G23 / G26 | B58 Gen2 | 2021–2024 |
| BMW 540i (incl. xDrive) | G30 / G31 | B58 | 2017–2023 |
| BMW 640i (incl. xDrive) | G32 | B58 | 2018–2023 |
| BMW 740i (incl. xDrive) | G11 / G12 | B58 | 2016–2022 |
| BMW 840i (incl. Gran Coupe, xDrive) | G14 / G15 / G16 | B58 | 2018+ |
| BMW X3 M40i | G01 | B58 | 2018–2024 |
| BMW X4 M40i | G02 | B58 | 2019–2024 |
| BMW X5 40i | G05 | B58 | 2019–2022 |
| BMW X6 40i | G06 | B58 | 2020–2023 |
| BMW X7 40i | G07 | B58 | 2019–2022 |
| BMW Z4 M40i | G29 | B58 | 2019+ |
Not compatible with hybrid or mild-hybrid equipped vehicles.
Running E85 on a standard JB4?
On Gen2 cars, the JB4 Fuel Pressure Upgrade Kit adds direct fuel pressure and fuel trim control. Not needed if you're buying the JB4PRO — that's already built in. Not compatible with Gen1 B58.
Prefer a flash tune?
We also carry the MHD Super License and the bootmod3 tune for the B58.