B58 JB4 - BMW M140, M240, 340i, 440i tuning box

The B58 JB4 is by far the most advanced tuning box available for the platform. The B58 JB4 connects to your MAP, TMAP and OBD as standard. With the OBD connection, the JB4 has access to real time engine data which it uses for tuning, logging and also safety. No other B58 M140i, M240i, 340i, 440i tuning box on the market uses real time canbus data, or has the safety systems like the JB4. If the JB4 detects any engine parameters going wrong, it will revert to a safety map.

The JB4 will not flash, edit, or remove any safety systems on your DME. This means that the JB4 can also be removed without leaving a trace. It is only with a flash tune you take the risk of the mapper being able to edit the critical tables within the DME and truly know what they are doing. It is possible that a mapper will aim for big dyno figures, at the risk of reducing safety parameters such as knock sensitivity or temperature. 

The B58 JB4 has multiple maps to support all levels of tune. Maps and firmware are regularly updated and enhanced, which you can download for free via either the optional USB data cable or Bluetooth connector. Maps include, and can support hardware for stage 1, stage 2, stage 3 and even fully integrated methanol injection maps (optional meth kit).

With the optional FSB and meth kit, the JB4 has fully integrated meth mapping and safety. For example, if the JB4 detects low meth flow, it will automatically revert to a low boost safety map, preventing any dangerous engine knock.

A question we regularly receive at Bolt ON Mods regards meth and JB4 is, "is it complicated to tune and set up?" The answer is no. The meth map built into the JB4 makes it all very straightforward. You simply adjust the "boost additive" in the meth map screen via the app for the level of power you want. BMS have perfected this and we advise keeping to the default settings as they are already so well dialled in for stock turbo applications. 

The JB4 has many other features as well as those for tuning. These include datalogging, code read/writing, can flap control, boost by gear control, stacking with flash tunes, and much more.

The B58 JB4 has optional connectors. By selecting them as part of a JB4 purchase you will benefit from a discounted package price.

The electronic waste gate harness (EWG) gives the JB4 more direct control of the wastegate, which is recommended for higher boost maps such as the meth map. 

The fuel harness allows the JB4 to datalog the HPFP, and increase rail pressure. This helps in situations where fuel trims are too high.

The B58 JB4 s compatible with the M140, M240i, 340i, and the 440i.

Full instal instructions and map guides can be found on N54tech.com