Home / FAQ - MS45 Tuning

What is flash tuning?

Also known as ‘remapping’ and ‘reflashing’, flash tuning involves calibrating the parameters of the engine’s “brain”- the Engine Control Unit (ECU). When the engine’s hardware is modified, the ECU must be recalibrated or tuned.

Vehicles rarely come fully optimized for performance from the factory. There are many reasons for this:

  1. Model hierarchy. This is the most common reason an engine is artificially restrained via tuning. Multiple vehicle models in a manufacturer’s range will utilize the same modular engine to save development costs. To maintain model hierarchy, manufacturers use various states of tune to limit models that are lower on the totem pole. An ECU tune can unlock this extra power.
  2. Extend an engine’s life cycle. This allows manufacturers to release mid-cycle refreshes with slightly more power and push owners to trade in their older vehicles for new models.
  3. Emissions. Variable valve timing can be manipulated to work as a pseudo-EGR and recycle spent exhaust gasses. However, if a cylinder fills 10% of its volume with spent exhaust gasses, the engine will perform like it has 10% less displacement.
  4. Varying environments. Factory tuning is usually conservative to account for the variety of environments in which the engine will be operated. At Severn Tuning, we use data logs from the customer’s vehicle to optimize it for the exact environment in which the vehicle is driven.

Flash tuning is separate from coding and diagnostics. It will not solve underlying mechanical or electronic issues, and in some cases, it can make problems worse. We highly recommend you consider tuning to be a final ECU calibration and the very last step when optimizing your vehicle.


How does it work?

After purchase, we will contact you for information about your vehicle's build and setup so that we can begin developing your base file. We will send you a link to download our FlashApp software and detailed installation instructions. We will also mail you a genuine BimmerGeeks Pro K+DCAN cable. FlashApp allows you to download the stock file from your car and write the modified file you purchased. FlashApp incorporates data logging capability, which we will use to confirm your vehicle’s tune is perfectly optimized. We will email you revisions of your tune as necessary.


What is included?

You will need a laptop that meets the minimum system requirements (see below). We provide everything else you will need to install the tune on your vehicle! We do not nickel and dime our customers by charging for a tune, and then additionally charging extra for the hardware and software necessary to put the tune on the vehicle. The only thing a customer needs to provide is a laptop which meets minimum hardware requirements. Each purchase is inclusive of the software and hardware needed to apply the tuning changes to the vehicle. This includes:

  1. FlashApp software
  2. K+DCAN cable, USB-to-OBD
  3. Shipping


What is FlashApp?

FlashApp is Severn Tuning’s proprietary tuning software. It allows the end user to:

  • Read the ECU’s stock file
  • Write tuned files provided by Severn Tuning
  • Monitor live values of engine parameters
  • Record data logs of engine parameters
  • Read and clear diagnostic trouble codes (DTCs)
  • Retrieve DME info
  • Clear adaptations
  • Interface with an optional DATAQ Instruments DI-1100 analog data acquisition module, which can capture up to four channels of analog data in parallel with OBD engine parameters (useful for logging boost, wideband AFR, oil pressure, or other sensors not fitted from the factory)

Read/write capability in FlashApp is VIN-locked to a single vehicle. Contact us if you would like to purchase additional vehicle licenses.


**Please note that EWS sync is under development at this time and not yet available**

 Minimum System Requirements

  • 1GHz CPU
  • 512MB RAM
  • Microsoft Windows® 7/8/10
  • Microsoft .NET Framework 4.6.1
  • USB 1.0

 Recommended System Requirements

  • 2GHz CPU
  • 1GB RAM
  • Microsoft Windows® 7/8/10
  • Microsoft .NET Framework 4.6.1
  • USB 2.0 or newer


Which BMW models are supported through Severn Tuning's MS45 tuning service?

  • 2003-2006 E46 3-Series
  • 2003-2005 E60 5-Series
  • 2003-2006 E83 X3
  • 2003-2005 E85 Z4


What power gains can I expect?

Power gains depend on the vehicle and its current state of optimization. On a completely stock vehicle, maximum gains will be approximately 15 horsepower with our Stage 1 ECU tune. Expect greater power gains the further the vehicle deviates from stock. We place reliability and drivability above power production, yet still tune the fastest MS45-equipped cars in the world.

Stage 2 power production is limited only by the vehicle’s hardware and the stock MAF sensor. Stage 3 tuning can support power up to the internal limits of the ECU – more than 600 horsepower!


I can buy a $200 tune from Tuner X. What makes your tune better?

We provide the absolute best tuning service, regardless of price. We do not try to follow a ‘cost leadership’ strategy, because tuning is not a commodity where products have very little differentiation. A calibration that is not optimized may have drivability problems or produce less power than it otherwise could. Worse, a bad tune can cause thousands of dollars of damage.

We have expended significant resources to bring a vastly expanded MS45 tuning solution to the aftermarket. A tuner selling $200 tunes has not, or he would not be in business for very long. Few companies have professionally licensed engineers on staff, and an experienced engineer’s time is not cheap. At the time of this writing, we are the only tuning company that offers the ability to tune for high boost on the MS45 ECU.