Ford Focus RS/ST JB4 Tuner

Power gains of up to 50whp and 60wtq to the wheels on a stock vehicle

The JB4 is a plug and play Ford Focus RS tuner that plugs into easy to access sensors in the engine bay and works with your factory ECU tuning to remap your boost, timing, and fueling for optimal performance and reduced turbo lag. It features a 64mhz processor allowing sensors to be sampled 800 times per second using dedicated 10-bit digital to analog converters, ensuring smooth and powerful performance.

Unlike other tuning systems, the JB4 includes a fully programmable CANbus system, upgradable firmware, and data logging capability. CANbus allows the JB4 to take into account pedal input, throttle position, gear, engine speed, air/fuel ratio, fuel trims, ignition advance, knock, and many other factors and incorporate those into the performance mapping. It can also read/delete fault codes, and includes unique safety features such as keeping boost pressure low until oil and water is up to temperature to provide proper engine and turbo lucubration and drop to a low boost map if the engine starts to overheat, run lean, excessively knock, or over boost.

The JB4 offers a lot more performance, functionality, and safety than your average performance chip.

The default JB4 map1 runs 4psi over stock peak, and tuned maps, including stock and valet mode, can be selected on the fly using a BMS diagnostics cable or JB4 mobile smartphone adapter.

Installation is very discrete, and it quickly removes without a trace when needed. Includes maps for 91 octane, 93 octane, and E85 (ethanol fuel) mixtures. Fuel economy during normal driving is unchanged. Compatible with all driving modes. Made in USA. 5 year warranty.

Wirelessly connect the JB4 to your Bluetooth 4.0 compatible iOS and Android device via the JB4 Mobile connect kit or to your Windows laptop with the BMS data cable. Both options allow 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. A separate JB4 Mobile app purchase is also required.

Ford Focus RS JB4 Features and Benefits

• Power gains of up to 50whp and 60wtq to the wheels on a stock vehicle
• Improves 0-60 times and 1/4 mile times
• Preloaded with custom JB4 Ford 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
• Made in the USA
• Free USA Shipping
• 5 year warranty

Vehicle Fitment

• 2016+ Ford Focus RS

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 its 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.