Since 2017, GM has tried to stop us from what we all like to do, turn these trucks up and go fast! The E41 ECM in the 2017 to current L5P Duramax has been long known as “locked” or “encrypted from the factory”, making it impossible to tune in the traditional sense. There are devices out on the market that piggyback the sensors under the hood, fooling the truck to build more boost, fuel pressure, and in turn, more horsepower. But if you wanted to “flash” the truck with a custom calibration, your only option was a costly ECM swap to an unlocked ECM from HP Tuners. Gone were the days of a simple EFI Live flashing like on the LML Duramax trucks. But it's not all bad news, now you have some options!
Option #1: Unlocked ECM from HP Tuners
The original option from HP Tuners, is to purchase a new unlocked ECM, which minimizes downtime as you can swap your ECM in and out in a matter of minutes. This option is the most costly, with unlocked ECM’s costing $2000, and it does come with its own host of “extra” necessary steps, as you are replacing your vehicle's ECM. After you complete the commanded swap procedure, which is a necessary step to carry over your injector codes from the original ECM to the new ECM, you are able to read and write the ECM with your MPVI2(3) in the VCM Editor Beta program.
You will commonly be sent two files, one VATS off file, and one VATS on. VATS stands for Vehicle Anti-Theft System. With the swap of the ECM, your key fob will not be learned to the new ECM, so the vehicle will not crank and will not start without a VATS off file. Once the immobilizer is relearned with a dealer tool, you may flash the vehicle with a VATS on file. This isn’t required 100%, however, if you do not relearn the immobilizer and flash the vehicle with a VATS on file, your truck could technically be started with a screwdriver jammed into the ignition. Another step which must be completed is a crank position relearn. This can be done through the VCM Scanner Beta program.