Power gains of up to 120whp and 120wtq. on a stock vehicle without the risks of flashing!

The JB4 is the most advanced and feature-rich tuning system available for BMW's B58 engines, offering significant power gains, seamless integration, and unparalleled ease of use. With its plug-and-play design and innovative features, the JB4 transforms your driving experience without requiring additional modifications.

Unlike traditional ECU flash tuning, the JB4 does not require staged upgrades or additional modifications. Install it as your first upgrade and immediately experience stronger turbo response, smoother power delivery, and significantly improved acceleration.

Also available with our new JB4PRO board For 2020+ Gen 2 which includes built in Bluetooth, fuel pressure control for more advanced tuning with ethanol mixtures, built in flex fuel/port injection/WMI control using our PNP add on harness, onboard data-logging memory, and many additional features to be unlocked in the future via free firmware updates. Perfect for those planning higher power builds including larger turbos and/or port injection/WMI. 

Optional fuel pressure connection for Gen2 B58: Allows the JB4 to directly control fuel pressure and fuel trims, particularly useful for vehicles running ethanol blends such as E30 or E85.

For B58 Engines:

• Power Gains: Up to 120hp to the wheels (140hp crank) on a completely stock engine with pump gas. Gains are even higher with bolt-ons, E85 fuel mixtures, or larger turbos. 
• Key Features:
  • Simple plug-and-play installation for quick setup and removal.
  • In-dash map switching: Seamlessly toggle between factory and performance maps.
  • Optional in-dash gauge displays for real-time metrics like boost.
  • Boost limiting by gear to enhance traction in lower gears.
  • Support for progressive water/methanol injection.
  • Built-in data logging and code reading capabilities.
  • Optional direct EWG control to prevent throttle closure with exhaust upgrades.
  • Exhaust flapper control for sound customization.
• Optional: For Extra Ordinary Performance with JB4 We recommend Our B58 Downpipe and B58 Air Intake

Wirelessly Connect to your JB4: Our all-new JB4 PRO smartphone connection is included 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 information about the JB4PRO mobile app click here.

JB4 Tuner 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

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

Fitment

Note: If your BMW has a B58 engine and you don't see your exact model on the list below or the links mentioned upper, please Message Us.

BMW 1 Series

• 2016-2019 F20 F21 GEN1 B58 BMW M140i

BMW 2 Series

• 2022-Present G42 Gen 2 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
  
• 2015-2019 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 B58 BMW X3 2.0i, X3 3.0i, X3 M40i including xDrive
  
• 2019-2024 G02 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 M40i

Other Vehicles

• 2022+ BMW GEN3 B58 JB4 Tuner - 228i (F44), 740i (G70), X1, X5, X7
• JB4 Tuner for B58 2020-Present Toyota Supra Mk5 (A90/A91)

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.

Is the JB4 a real tune?

Yes. The JB4 actively adjusts boost, timing, air-fuel ratios, and fuel trims using real-time engine data through its CANbus connection. This allows it to produce performance gains similar to ECU flash tuning without permanently modifying the 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

2017 BMW 230i with B48 Engine, JB4

VIDEOS

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

CAN FLAP DEMO

BMW B58 JB4 Install Videos