So you want more power from your Roadster eh?

Smart Roadsters use a Bosch MEG1.1 ECU unit.

M stands for “Bosch Motronic” which can be traced back to Bosch’s first ECUs back in the 80s

E stands for “electronic accelerator” all Smart ECUs use drive-by-wire throttles where the accelerator pedal isn’t actually physically connected to the throttle body.

G stands for “Gearbox Control” all 450 Fortwo and Roadsters have the gearbox controlled by the ECU itself.

Unlike other Bosch ECUs like the ME7.5, the MEG1.1 in the Roadster has not had much reverse engineering done to it because the Roadster (and 450 Fortwo) are the only models which use this ECU.

Roadsters and 700cc Fortwos share the same MEG1.1 ECU and can be exchanged between the two with a bit of knowledge.

The MEG has two areas inside that can store information, the EEPROM and FLASH.

The EEPROM stores information about the car such as VIN number, engine model, immobilizer key programming, clutch grab point, gearbox learning adaptations and what options are enabled such as weather the Brabus tuning SB2 map has been applied or not.

The FLASH storage is a bigger chip that stores the “firmware” or the part that actually runs the engine and gearbox, this is where all the tables for how much fuel to put in, how much timing and how much boost to run.

When someone “remaps” the ecu, this is the chip that gets overwritten. EEPROM on the other hand is difficult to edit, usually requires removing the ECU from the car, opening it up and removing the entire chip off the board just to read and reflash it.

When someone “clones” an MEG, SAM or cluster, this is what they are doing; removing, reading and cloning the data on the internal EEPROM chips.

45kw Roadster Lite and 61kw regular Roadsters use the same map file, there are multiple maps inside the FLASH and the EEPROM tells it which maps to use.

Over the life of the roadster, there were 5 different revisions or versions for the 45/61kw that got released:

• 1037365163
• 1037365186
• 1037365239
• 1037365463
• 1037371568

Most of the changes between the versions are just small tweaks here and there to things like cold start, clutch engagement and emissions.

371568 is the biggest change of the lot, this is the one that got released in 2006? and was made after complaints that the gear changes were slow. This version has many tweaks to the gearbox control, driving it you can definitely notice the difference and gear changes are both faster and smoother.

Brabus Roadster (74kw and SB2) does have their own unique map files and there was only ever one version of each released. What this means that when the 371568 updated 61kw version got released, the Brabus models missed out on quicker and smoother gear changes.

The SB2 map, like all the maps have built in protection, you cant just load it using a flash tool to the ECU like other map files as the car will go into limp mode within a few minutes. The way this works is inside the EEPROM is an area that mentions if the car has had the SB2 map applied or not.

If the ECU starts and isn’t a model with the SB2 map applied but has the SB2 map loaded onto the FLASH then it goes into some sort of protection mode (limp mode) within a few minutes.

This is the same with 45/61kw variations, they use the same map but inside the EEPROM it states which variant it is and which internal values to reference.

The way the Smart dealers apply the SB2 map is with the STAR diagnostics unit, it updates both the FLASH and EEPROM to both be SB2.

Most people (who aren’t Mercedes) use STAR systems that aren’t genuine or legal. The way these work is mainly offline (no connection to Mercedes servers). To be able to use the SB2 map, the EEPROM needs to be edited to match the map file and this is called SCN coding on the STAR units.

Offline SCN coding is rare and not many people have the ability to do this. This means that loading the Brabus SB2 map via a STAR diagnostics unit is extremely rare outside of Mercedes.

Most generic “remappers” out there (who aren’t Smart specialists) who say they can reflash your Roadsters if you bring in your car will load a tune which they themselves have probably found online from an illegal leaked database.

These databases are the same ones which can be bought on eBay for a very small amount of money. They are the same bunch of files from pretty much every seller.

Only tuners which are smart specialists or have a dyno and have developed their own tune are to be relied upon.

Big thanks to Mike Bailey at 223D Developmental who has helped (and pushed) me to discover more along with Andrew at Smart Automotive who has also collaborated on this journey.

More posts to follow…