Frequently Asked Questions

Please refer to your state’s emission standards to determine the smog laws. Our tune is meant to be used for off-road and closed circuit competition use only.

Yes if you make modifications to your exhaust you can potentially increase the unpleasant smell inside the cabin. To reduce the smell make sure you use the proper gaskets to seal each pipe section as well as periodically checking for any leaks or cracks. MPG will drop to about 19.2 MPG.

Depending on which of the stage you choose, it will happen at different RPM points. Try revving it out to 3k-6k RPM WOT and release the accelerator completely. Then tap the accelerator to activate.

The backfire tune is designed for catless cars only. Even if you do not care about your catalytic converters, the heat trapped between the engine and the catalytic converter is not good for your motor. You may also destroy both your pre and post o2 sensors from the trapped heat with catalytic converters. For catted cars, you need all four of those sensor to function, otherwise your car will not run properly and potentially experience misfires. However, the B-Spec performance tune itself can be used with both catted and catless setups.

We recommend catless headers, intake, and exhaust.

We have tested extensively for over 12 months, however we advise that you use this tune at your own risk. We are not responsible for any damages to your car from our tune. Please see our Terms of Service and Privacy Policy.

Flames are occasional as we want it to be a conservative tune, when the exhaust is hot you will see some flames. We’ve seen some tunes on the market constantly shooting flames. NOT SAFE FOR ENGINE.

US 91+ Octane Required. Knocking will occur with lower octanes.

LC works off of the front wheel sensor and is activated when sensor reads 0 mph.

Use a less aggressive tune and check your cooling system. Different climates and temperatures will affect how much heat is dissipated after a backfire. Almost all our test vehicles with a recent cooling system refresh has no issues at all with any of the backfires stages and levels. If you are having issues, it is very likely your cooling system isn’t up to par and needs a refresh.

  • Use a less aggressive backfire stage and check your injectors for clogs. Sometimes, not enough fuel is injected for the tune. We tuned with OEM Spec injectors in mind.
  • Disable EGT Sensor with the Tool. EGT sensor tries to compensate the increase fuel.
  • Disable Post O2 Sensors
  • Bad fuel
  • Bad fuel pump
  • Clogged fuel filter
  • Bad ignition coils
  • Bad injectors
  • Bad spark plugs
  • Reset Fuel Adaptions using BMWLogger or INPA
  • ICV Valve is clogged
  • Disable cold start
  • Bad ignition coils
  • Bad spark plugs
  • Bad injectors
  • Bad fuel pump
  • Clogged fuel filter
  • Your E85 ratio is too high. Add more 91 octane.

No, we only change the mappings for the overrun where power is not being tuned or made. ECUWorx’s tool will keep your existing tune intact. B Spec Tune will overwrite your existing tune.

Probably yes, but hasn’t been tested with F/I.

Depends if your tune is encrypted and scrambled by your tuner. If ECUWorx tool cannot read it, we cannot modify it. Go complain to your tuner as they have locked up your ECU tune.

We recommend driving your M3 normally as you would and increasingly drive it more aggressively as your M3 adapts to your tune via the fuel trims. The backfire feature will add excitement to your driving experience. However, triggering backfire feature continuously for hours without any break for the engine to cool down is not recommended. If you notice any issues, flash the car back to its original tune and please refer to the FAQ below for troubleshooting. Alternatively, you can reset fuel adaptions via INPA or BMWLogger.

Additional Support

We will likely be making changes as we get feedback from the community. Simply flash back to your stock tune. Then email thebuildjournal@gmail.com with your symptoms along with DME Code readout (We need this to ensure it is not an isolated case and is caused by malfunctioning part on your car). If you have any questions or feedback, please email us at thebuildjournal@gmail.com or feel free to post on our M3Forum thread.