E46 Ms42 Ms43 ecu tuning

B.A. Tuned Replacement ECU

Getting a custom tuned ECU is now simple. Just order and we will ship you an ECU that is ready to drop in and go. If you would like to send in your core and save $50, please see this listing HERE.


Buy From the BEST; we have been tuning these cars for years and the speed of our Time-Attack E46 proves this point! Full tech support included, we are here to help your right foot make you smile! We have a ton of experience with this platform and have made over 700hp using the aluminum M54 block. If you need a custom turbo or supercharger tune please let us know. 


Instructions can be viewed HERE


We have teamed up with Belsky Autowerks to provide the best tuning and service available. Vlad is one of the best tuners we know, is very technical with his approach, and specializes in BMW tuning. He takes the time to remove each ECU from its case, inspect it, essentially jailbreak it, and then load a tune onto it that is specifically made for you depending on which options you want. Truly a custom tune, no off-the-shelf bs. Not just a throttle map change. fueling, VANOS and timing maps all edited for maximum performance. 91 or 93 octane fuel is required for best performance, otherwise knock sensors will remove timing. 


These ECU's also have the EWS deleted, so it can also repair vehicles with a bad ECU or EWS system without the need to visit a shop for expensive programming, or be used in an engine swap project. Just plug it in and go.


This ECU offers similar gains to the "Shark" tune, the AA tune, and makes the throttle respond like the "Sprint Booster" would, but for much less and way more options! Do not use it in conjunction with the "Sprint Booster". Options get the most out of headers and M50 manifold swaps compared to off the shelf tunes like AA and Shark. 


Now, lets go over the options:


ECU/Engine version:

MS42 comes in all 323 and 328 models. The 325 has a 2.5 and the 328 has a 2.8

MS43 comes in the following models, with the 325 being the 2.5 and the 330 the 3.0.

  • All E46 Xi models, regardless of year
  • E46 325 and 330 vehicles built before mid-2003. If your MAF sensor has 3 wires, you are MS43 
  • All E39 525 and 530 models
  • All 2003-2006 X3 E83 models
  • All 1999-2006 X5 E53 models with a 3 Liter engine


Intake Manifold: Select which you'll be using, we tweak the VANOS and other maps to get the most out of cars using our M50 manifold swap which can be found here. this will also allow you to use the normal E36 air temp sensor that comes with the m50 manifold instead of retrofitting the original plastic M52TU/M54 temp sensor. Note: If you select this and run the factory M54 plastic temp sensor, it will run terrible: M50 Swap


Headers/SAP: If you are running headers, or plan on installing them later, select yes here. We will delete the monitoring of the downstream O2 sensors which monitor catalytic converter efficiency (removed with headers). We also open up the maps a bit to make up for the engine breathing a bit better. You can also remove the bulky secondary air pump with this option. With these options you won't get the check engine light when installing headers for some great power gains. Off-Road use only. 


Rev Limit: Get that motor singing! This is a great option especially if you're using headers and/or a M50 manifold. We do not recommend raising the rev limit above 6500 on vehicles without an oil pump solution, which can be found here: Oil Pump


Thermostat/Fan Temp Mod: These engines have an electronic thermostat and manual models have an electric fan, so this makes adjusting the running temp a breeze. They came with super high target coolant temps for emissions tests, but if you are tracking your car or running hard it gets hard for the cooling system to keep up. With this mod you have a greater buffer as the motor will target a lower coolant temperature.  


Increased Idle RPM: This is a great option if you have a single piece flywheel. These often create a chatter, but slightly raising the idle RPM makes this go away. 

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