Power gains of up to 120WHP and 120WTQ on a stock vehicle without the risks of flashing!

The JB4 is the most advanced and highly featured tuning system available for your B58 powered BMW. Power gains are up to 120hp to the wheels (140hp crank) on a completely stock B58 engine on pump gas, gains with bolt-on parts, higher octane, E85 mixtures, and larger turbos are even higher.

No ECU flash needed and compatible with locked 🔒 ECUs

The JB4 features a simple plug & play installation harness for easy installation & removal and includes many features not found with any other tune. Including on the fly map switching between factory and various performance maps, boost limiting by gear for improved traction in lower gears, progressive water/methanol support, built-in data logging, built-in code reading, direct EWG control to prevent throttle closure with exhaust modifications, exhaust flapper control (most models), and much more. Other more expensive tuners may claim to equal the JB4's technology but upon closer examination lack most if not all of the JB4's features.

Remember the JB4 does not require any additional modifications or previous stages. Simply install it as your first and only modification and enjoy an entirely new, fast, and smooth racing experience. The JB4 also does not require any user setup or customization, but for those who are interested in changing maps, logging, customization, and loading new features as we add them, we suggest adding one of our Bluetooth phone adapters!

Optional fuel pressure connection for Gen2 B58: Allows the JB4 to directly control fuel pressure and fuel trims, useful for those running E85 mixtures.

Wirelessly Connect to your JB4: Grab our all-new JB4 PRO smartphone connection to wirelessly connect the JB4 tuner to your Bluetooth 4.0 compatible iOS or Android device. This option allows you to record and analyze vehicle and tuning data, change JB4 performance maps, and update JB4 firmware as we release free newer versions with updates, more powerful maps, and new features under development. Our new adapter fits fully inside the JB4 enclosure for enhanced weather protection and a more streamlined look. The JB4PRO Free app features an intuitive easy-to-use interface, help buttons, and advanced log analysis tools that can estimate the performance of your car and help identify any tuning concerns. For more info on how to use the JB4PRO free app click here.

JB4 Map Guide:

Map0: Stock tuning, fully disable JB4
Map1: 3psi over stock added (91 octane)
Map2: 4psi over stock added (91-93 octane)
Map3: 6psi over stock added (93+ octane)
Map4: Absolute target map with peak target of 20psi (93+ and/or 30% E85, EWG connector suggested)
Map5: Absolute target map with peak target of 22psi (30% E85+ fuel, EWG connector suggested)
Map6: Custom tuning map -- see details on JB4tech.com B58 JB4 page
Map7: Progressive WMI map with tuning a function of meth flow and user-defined boost additive.
Map8: VALET / Low Boost Map

This B58 JB4 model is compatible with all GEN1 and GEN2 B58 motors. For the newest B58TU2 GEN3 motor refer to this product page.

JB4_B58 is CARB Approved Under Executive Order (EO) No.D-744-4 for all 2016-2018 BMW 230i, 330i, 430i, 530i, 340i, 440i, 740i, M240i, and X1 applications.

JB4 Power Gains, Features, & Benefits

• Power gains of up to 120hp to the wheels on a stock vehicle
• Improves 0-60 times and 1/4 mile times
• Preloaded with custom JB4 BMW tuning software and up to 8 maps for various fuel and modification levels
• Ethanol (E85) compatible tuning maps
• Able to read/delete fault codes
• View and record up to 40 different gauges/engine parameters in real time with the JB4 app.
• Boost by gear in 1st, 2nd, and 3rd can be controlled via the JB4 app for a perfect launch
• Exhaust flap operation can be controlled in most JB4 applications
• Compatible with JB4 Mobile for smartphone logging, tuning changes, and adjustment
• The JB4 offers a lot more performance, functionality, and safety than your average performance chip
• Quick Plug & Play Installation
• CANbus OBDII integration offering unrivaled tuning features and performance
• Improved performance over non-integrated chip tunes
• Runs as smoothly as stock, this is how your vehicle should have come from the factory
• Compatible with all driving modes
• Fuel economy unchanged during normal driving
• 91 octane fuel or better required for performance gains
• Not VIN locked and can be removed without a trace and resold down the road
• Includes the rugged JB4 billet aluminum enclosure for protection
• Designed and assembled in the USA
• Free USA Shipping
• 5-year warranty

Vehicle Fitment (GEN1 & GEN2 B58)

Note: If your BMW has a GEN1 OR GEN2 B58 engine and you don't see your exact model on the list below please email us. For the newest B58TU2 GEN3 motor refer to this product page.

BMW 1 Series
• 2016-2019 F20 F21 GEN1 B58 BMW M140i

BMW 2 Series
• 2022+ G42 GEN2 B58 BMW M240i including xDrive
• 2016-2021 F22 F23 GEN1 B58 BMW M240i including xDrive

BMW 3 Series
• 2020-2024 G20 G21 GEN2 B58 BMW M340i including xDrive
• 2016-2018 F30 GEN1 B58 BMW 340i including xDrive

BMW 4 Series
• 2021-2024 G22 G23 G26 GEN2 B58 BMW M440i including Gran Coupe and xDrive
• 2016-2020 F32 F33 F36 GEN1 B58 BMW 440i including Gran Coupe and xDrive

BMW 5 Series
• 2017-2023 G30 G31 GEN2 B58 BMW 540i including xDrive

BMW 6 Series
• 2018-2023 G32 G33 GEN2 B58 BMW 640i including xDrive

BMW 7 Series
• 2016-2022 G11 G12 B58 BMW 740i including xDrive

BMW 8 Series
• 2018+ G15 G14 G16 GEN1 & GEN2 B58 BMW 840i including Gran Coupe and xDrive

BMW X Series
• 2018-2024 G01 B48 B58 BMW X3 2.0i, X3 3.0i, X3 M40i including xDrive
• 2019-2024 G02 B48 B58 BMW X4 2.0i, X4 3.0i, X4 M40i including xDrive
• 2019-2022 G05 B58 BMW X5 40i including xDrive
• 2020-2023 G06 B58 X6 40i xDrive
• 2019-2022 G07 B58 BMW X7 40i including xDrive

BMW Z4
• 2019+ G29 B58 BMW Z4 M40

What is a JB4?

The JB4 is a plug & play tune available for turbocharged vehicles. The JB4 tuner installs between your car's sensors and the DME/ECU (computer) and manipulates vehicle performance through these connections making your vehicle much faster. While it's not the only tuning system that operates this way the JB4 separates itself from the competition with much more advanced connection points and processing including CANbus, fuel & spark control, Bluetooth to your smartphone, and a variety of innovative and advanced features not possible with any other system. BMS regularly publishes free mapping and firmware updates adding performance and features as ongoing development allows. In addition, the JB4 system is not VIN-locked to your vehicle and can quickly be removed and swapped between cars or resold at a later time. Often imitated but never duplicated the JB4 has been the gold standard in plug and play turbocharged performance tuning for over a decade and is sold in over 67 countries worldwide.

Is the JB4 a real tune?

Yes the JB4 is a real tune. By tapping into specific sensors and CANbus for real time vehicle data the JB4 is able to alter your boost, timing, AFR, and/or fuel trims, to a similar degree an ECU reflash would, but without the vehicle ever knowing its been tuned. The result is safe, smooth, and significant power and torque gains while retaining your factory safety systems and without having to unlock/flag your ECU.

California Customers -- Download the CARB Version Installation Guide

Stock vs. JB4 DYNO RESULTS

2020 BMW B58 M340i JB4 + BMS B58 Competition Intake and E30

2016 BMW 340xi B58, JB4, no other mods, 93 Octane vs E30

2020 B58 Powered BMW Z4 Dyno - 490whp with JB4 Map 5 and E40 mixture

No M? No problem! JB4 Tuned 240i beats G80 M3.

CAN FLAP DEMO

BMW B38/B46/B48/B58 JB4 Install Videos