Bosch Motorsport MS4.0 ECU For E46 M3

Bosch Motorsport and Turner Motorsport have teamed up to offer a plug-and-play, tunable ECU system for the E46 M3 (6MT manual transmission). The Bosch Motorsport ECU opens the doors for unlimited tuning potential and instant power and reliability benefits over the stock BMW ECU. The Bosch Motorsport plug-n-play ECU cuts through all of the hassle and additional work that normally comes with switching to a aftermarket management system (MoTeC, EFI, etc.). It also leapfrogs the stock BMW system in advanced tuning and reliability.

In designing this system, Bosch and Turner Motorsport set 5 goals:
    1. Create and develop a fully integrated and programmable engine management system that offered superior performance (horsepower!) over the stock ECU system,
    2. The system must be plug and play to the vehicle with minimal intrusion on existing systems,
    3. As a minimum for normal car operation, the system must be functional with: stock instrument cluster, ignition switch, and factory ABS system,
    4. The system be flexible (and tunable) to allow modification for future upgrades and additional features,
    5. Attractive cost.
The end results exceeded all of our goals!

Features of the Bosch Motorsport ECU System:

minimal intrusion during installation - works with existing wiring

The system is a direct plug-in for your 2001-2006 E46 M3. We have built this system so that the ECU package will plug in to your M3’s existing wiring harness and work with nearly all of the stock hardware including the instrument cluster. The basic system consists of: Bosch MS4.0 ECU, translator box, Bosch ECU data cable to laptop, Bosch Lambda sensors, and pre-loaded software. It combines the many features and benefits of other racing stand-alone ECU systems while working with the factory wiring and CAN system. There’s no time wasted with this system. You don’t have to build an engine wiring harness, mate it to a chassis harness, buy each individual sensor, set up and configure a base tune, or incorporate a racing dash display. With the Bosch Motorsport programmable plug-n-play ECU you can be up and running in about an hour.

We recommend that you have fresh Bosch ignition coils installed. BMW had one recall for Bremi brand coils and then changed from ERA brand to Bosch. The coils that we use are BMW part number 12 13 1 712 219 and you can find them on our site here: Worn coils may result in misfires or rough running and these issues may be masked by the low demands of the stock ECU.

maps and engine tuning can be adjusted via laptop

The Bosch Motorsport ECU does away with the limitations of the stock ECU and opens up tuning possibilities you didn’t have before. With Bosch, the focus is only on optimizing engine management and maximizing horsepower output. There are no hidden limp modes or interference. Adjustments are done via Bosch PC tuning software. Individual tuning is encouraged as every engine and spec is slightly different and the best way to maximize power is by tailoring it to your setup. The Bosch ECU can hold 3 maps at a time, each can be selected from the factory Sport Mode button on the center console while the car is running.

system starts at only $4,995 - including base map

The system includes the Bosch Motorsport ECU, translator box, and a pair of Bosch LSU4.9 Lambda sensors. You don’t need to build a wiring harness and replace every sensor, ignition coil, injectors, VANOS igniters, or electronic throttles. You don’t need an aftermarket dash display (though one can be easily integrated with our system). The Bosch Motorsport ECU in our kit is powerful compared to other full aftermarket race ECUs which still require additional parts and custom wiring harnesses and many of hours of work to install. A comparable MoTeC system can be triple the cost before the engine is even started. Factor in dyno work and the time to develop a base map (which we also include) and the Bosch Motorsport ECU system for the E46 M3 is a bargain.

simple, reliable, and effective - the opposite of the stock M3’s ECU

The stock E46 M3 ECU was not designed to be modified for track and motorsport use. It was engineered to meet and maintain specific targets for emissions, fuel economy, and diagnostic control. That control can wreak havoc on a track/race car where emissions equipment and OBD diagnostics are no longer wanted or required. Why use an ECU that fights back? The stock ECU, with its limp modes, restricted tuning access, and limited number of flashes, will fight you every step of the way when properly building a car for track use.

base maps tuned for common E46 M3 upgrades

Turner Motorsport and Bosch have worked up dyno-tuned base maps for all of the popular modifications to the S54 engine. We developed tuning maps for: a stock engine, intakes, several different header designs with cat delete, CSL-style carbon intake manifold, and aftermarket cams. It can also be used for engine management on forced induction engines. We have a base supercharger file that gained 50whp on a Dinan Vortech supercharger setup. When you purchase the system it comes pre-loaded with a base map that is consistent with the current spec of your vehicle. Additional fine-tuning of the software to maximize your output is encouraged but may not be required because our extensive dyno tuning may be perfect right out of the box.

get access to new maps that we develop

As we continue to develop new products for the M3 we will update and refine our own software maps and make them available to you. We will also update and tweak our existing maps based on additional tuning and use.


Bosch Motorsport MS ECUs are used by race teams around the world, including multiple racing series in the USA (it was the spec-ECU in the Grand-Am series). Turner Motorsport, as well as many other race shops, has extensive experience with this unit, racing with it in our E46 M3, E46 330i, E90 328i, Rolex GT M3, and Continental Tire E92 M3. Any team that has raced in Grand-Am or IMSA has experience tuning with this ECU. In these applications it functions as a true stand-alone with custom wiring and additional race-grade sensors and other hardware. The Turner E46 M3 project is the first time this ECU has been integrated into the factory wiring and CAN system.

The Bosch Motorsport ECU features 8 ignition drivers and 8 injection power stages to provide engine management up to eight cylinder engines. In addition to controlling the motor this ECU can be configured to work with data logging, traction control, launch control, and a pit lane speed limiter. When connected to the E46 M3-specific translator box, it employs full control over VANOS cam timing, ignition timing, fuel injection timing, and drive-by-wire.

This system uses two ultra-high performance Bosch LSU4.9 Lambda sensors to feed engine data back to the ECU. The 4.9 is a wideband, dual cell sensor with an integrated heating circuit. They replace the two pre-cat oxygen sensors used in the stock setup. The factory post-cat and EGT sensors are not used and can be removed or left in place.


The Bosch Motorsport ECU is a map-based tuning platform similar to other "alpha-n" type management systems which do not use an HFM. We provide you with a pre-loaded base map as a starting point. The base map will be based around the list of modifications you provide and should be very close right out of the box. From there you can make adjustments and fine tune the map using the Bosch Motorsport software to create a perfect match to your engine spec. Having the ability and access to tune your car for your specs in real time is a big advantage over the traditional flash tune. But the best part is that there is never a limp mode to ruin your day!

The Bosch Motorsport ECU will come pre-loaded with one of the files listed below. The files are not encrypted or protected - you are free to adjust and tweak as much as you like. Making adjustments is encouraged as alpha-n type systems work best when customized to the specific chassis they're installed on. You have full control over engine fuel maps, ignition mapping, as well as cam timing, and more. Additional map files can be supplied by Turner Motorsport starting at $250.

We developed base maps on our dyno using popular off-the-shelf upgrades:

base/100% stock
aFe intake
'eBay' headers, cat delete
'eBay' headers, cat delete, aFe intake
Euro headers, cat delete
Euro headers, cat delete, aFe intake
Supersprint stepped headers, cat delete
Supersprint stepped headers, cat delete, aFe intake
CSL-style carbon intake, Supersprint stepped headers, cat delete
Schrick CSL camshafts, Supersprint stepped headers, cat delete
Schrick CSL camshafts, Supersprint stepped headers, cat delete, aFe intake
Schrick CSL camshafts, CSL-style carbon intake, Supersprint stepped headers, cat delete
3.5-liter S54 stroker, headers, cat delete
Supercharger, headers, cat delete, stock cams (base map file, additional tuning will be required based on your exact setup)

In addition, other parameters that can be customized:

rev limit per gear
pit lane speed
idle speed / pedal mapping
electric fan operation
wheel speed diameter

As with most motorsport-derived management system, the Bosch ECU can be used with a data logger, race dash, traction and launch controls, and other systems. Additional hardware, wiring, programming, and software will be required. TMS or one of our fully trained installation centers can help set up and program these advanced features.


The translator box interfaces with the stock engine harness and interprets signals between the chassis and the Bosch Motorsport ECU. It is specific to the E46 M3 chassis only. Extensive development and reverse engineering of the stock system was required to retain as much operation as possible.

Original E46 Features / Systems Retained:
  • stock wiring harness
  • stock instrument cluster (aftermarket race dash can be implemented)
    • speedometer
    • tachometer
    • stock fuel gauge
    • stock oil temp gauge
    • oil pressure warning
    • stock coolant temp gauge
  • stock crankshaft and camshaft sensors
  • stock VANOS control solenoids
  • stock ignition coils
  • stock fuel injectors
  • stock fuel pump controls
  • stock keys (starting sequence changes slightly)
  • ABS
  • air conditioning system
  • stock drive-by-wire motors

  • Original E46 Features / Systems Not Supported:

    Since this is a full motorsport-grade system, some features typically found on street cars will be lost:

  • emissions controls
  • cruise control
  • TPMS
  • steering wheel controls
  • oil level sensor
  • separate idle control (Bosch ECU uses throttle position to set idle speed)
  • stock OBD diagnostic connectivity
  • EWS immobilizer
  • stock DSC (race traction control and launch control are optional)

  • This ECU system is not emissions compliant so any usage of this system on a street car is entirely at the owner’s risk.


    Stock vs. Bosch (no mods)

    Stock vs. Bosch with headers and CSL airbox