Cracking The Uncrackable L5P Duramax

Ladies and gentlemen, the impossible has happened. Experts said it could never be done on a commercial scale, and enthusiasts may have given up hope, but just a few weeks ago, we learned that Edge Products has cracked the code that was said to be uncrackable. Specifically, we’re talking about the ability to flash a performance tune into the E41 engine control module that runs the 6.6-liter L5P Duramax engine found in some 2017 and newer GM pickups. Edge has just released their Evo HT2 programmer with Locksmith tool which can tune the L5P Duramax ECM and add up to 150 horsepower and 350 lb.ft. of torque at the wheels WITHOUT having to remove the ECM from the truck.

Now, you may be thinking “what’s the big deal? Owners have been flash tuning their diesel trucks for the last two decades, right?” The simple feat of flash tuning an L5P may not sound that impressive if you’re accustomed to working on Ford and Ram trucks, but until now, the newest generation of Duramax that could be flash tuned through the OBD2 port was the LML.

When the L5P Duramax first hit the streets in the fall of 2016, enthusiasts were impressed with its initial horsepower and torque from the factory, which measured in at 445 and 910 respectively, but of course we always want more. At the time, diesel owners had become accustomed to flash programmers and custom tuning being readily available which can add significant power gains in just minutes, so Duramax fans headed to the dealerships in droves, and as soon as they had their keys, they began asking their favorite tuning company “How much power can we add?” Unfortunately, the answer to that question was “None” and as soon as the follow-up question “Well, how long do I have to wait?” was asked, the answer disappointed everyone.

The L5P Duramax Will Never Be Tuned. Period.

On September 24, 2017, a statement was issued on a Duramax discussion forum which made the bold claim that the L5P Duramax ECM would never be tuned, and the security protocols were so advanced, even the NSA would not be able to tackle the job. The post went into further detail about the security advancements GM made on the E41 ECM, and the claims were backed up by some anecdotical evidence provided by the I.T. manager of a large dealership chain.

While it was sort of a “he-said, she said” scenario, apparently General Motors used something called a Diffie-Hellman 2048-bit key exchange in addition to an SHA-256 hash digest to prevent anyone other than a GM dealership from being able to alter the programming of the E41 ECM. The security protocols GM employed were so intense, it would take years for an advanced computer to peel back the security on a single ECM, and because each truck uses a different combination or code, effectively this meant the L5P would be impossible to tune on a commercial scale. While that was a major bummer to the consumer who bought an L5P hoping to add a few aftermarket goodies, many owners knew it would be worth the wait, since the L5P showed potential for some great power gains, if only they could be unlocked. So, the aftermarket rolled up their sleeves and accepted the challenge, then got to work.

Here’s an excerpt of the initial post from Duramax Forum discussing the “uncrackable” ECM found on the L5P Duramax’s:

A Workaround Is Better Than Nothing

About a year after the original post was made claiming the L5P was impossible to tune, HP Tuners announced they had developed a solution for tuning the L5P. This was in the fall of 2018, and the L5P had been on the road for about two years. It had earned a reputation of being an efficient and reliable powerplant free of the injection pump woes that plagued the earlier LML, and owners were anxious to see how much extra power could be extracted from the brand-new Duramax, and HP Tuners offered the tools needed to find out. Rather than using brute force computing power to crack the encryption, they developed a circuit board level hardware modification to bypass whatever security module was inside the E41 computer. This modification allowed the ECM to accept an aftermarket calibration via HP Tuners software. Depending on which tune shop was writing the actual calibration, varying levels of power gains were seen, but this demonstrated the true performance potential of the L5P Duramax, and needless to say, the numbers were impressive.

Enthusiasts saw this as a huge victory because now their trucks could be tuned, but the process was a bit cumbersome, especially if a novice installer was involved. First, you had to remove the stock computer from your truck and send it in to HP Tuners, and in exchange they would send you an already modified ECM which you would install back in your truck. Even with expedited shipping, this would mean you’re without the truck for at least a few days, but once you had a modified ECM installed in the truck, the tuning process could begin. Since HP Tuners only offers the modified ECM along with the interface and software needed to flash the tune, you would also need to work with a custom calibrator who would provide the file you could load onto your new modified ECM, but only after a crank-relearn and immobilizer reset had been performed. If all the steps had been performed correctly, your L5P would be running stronger than ever and have increased throttle response along with customized tunes for towing or hot-rodding, but there were a few obstacles some users ran into.

When removing the ECM from the truck, installers quickly realized the plastic connectors on the wiring harness were easy to break, in addition to the plastic tabs on the ECM which the connector attached to. If either part broke, the ECM would be unusable (no core refund) or the wiring harness wouldn’t make a solid connection which leads to drivability issues. On top of all that, if you hired an inexperienced tuner to write your calibration file, your truck could run worse than before, and we can’t forget about the factor of cost. By the time you bought a modified ECM (and TCM if you wanted transmission tuning), the credits and hardware required to tune it, and the tune file itself, you could easily spend $3,000 or more. Needless to say, back in 2018 a tuned L5P was cost prohibitive, although it was the only option available if you wanted complete control over the truck’s calibration.

A few other workarounds have also been developed over the years which provide a healthy bump in performance to the L5P. Banks Power leaves the stock ECM in place, and rather than re-flashing, the Derringer Inline Tuner intercepts a few sensors on the engine and alters their signals before passing them back into the ECM. This allows for an increase in fuel pressure and turbo boost which will add up to 81 horsepower which is impressive, especially considering the much lower cost, but when it came to changing tire size, shift points, or transmission tuning, you were out of luck. There was a significant gap in the market between a full-on custom tune with a modified ECU and an in-line tuner which seemed out of reach due to that pesky encryption GM used in their computers, but given enough patience and determination, the folks at Edge Products were able to do what many thought would never happen and fill that gap in the market.

5 Years Later, The Impossible Has Happened

The average truck builder will have no true understanding or appreciation of how much work went into developing a tool that could flash a tune directly into the L5P’s ECM, but you can bet it took several years of work from a team who is at the top of their game. Despite all the high-tech security features GM put in place, Edge Products has done the impossible. A tune can now be loaded directly into the truck using their Evo HT2 handheld tuner, but the real magic happens with their appropriately named “Locksmith” device. This allows the ECM to be unlocked without any hardware modification and without even removing it from the truck which means no more risk of breaking connectors, no more waiting on a modified ECM, and no more core charges. Simply plug the Evo HT2 and Locksmith into your truck, follow the instructions, and before you know it, you can enjoy up to 150 additional horsepower and 350 more lb.ft. of torque AT THE WHEELS which gives a total of 525hp and 1,244lb.ft. as measured by a chassis dyno. While the power gains from the extreme tune are impressive, there are a total of four power settings you can choose from to suit your driving situation. A Heavy Tow tune offers +75hp and +150tq, an Economy tune gives +100hp and +200tq, a light trailer tune gives +125hp and +250tq, and of course there’s the extreme tune we already mentioned which will improve your quarter mile time by 1.3 seconds and 8 MPH.

While the performance figures are impressive, the Evo HT2 offers so many more options and features you can customize to your liking. The two I’m looking forward to most are the ability to adjust the throttle pedal sensitivity to get rid of the dead-pedal effect, and the new “remember last” setting. This will allow the truck to recall certain settings like tow/haul mode and the exhaust brake position so when you turn the truck off and start it back up again, it will retain the same settings, so you don’t have to re-engage those each time you stop for fuel or turn off of the truck. In addition, you can also read and clear DTC codes, adjust the TPMS settings, calibrate the speedometer for shorter or taller tires, adjust the high idle RPM, raise the RPM and speed limiter, and a whole lot more. The best part is the calibrations have passed Edge’s in-house emissions testing, and overall, the Evo HT2 and Locksmith combination is the most cost-effective way to tune an L5P, hands down.

No, It Won’t Let You Delete Your Truck

I follow several L5P specific discussion boards, and as soon as the announcement was made, there were dozens of comments made inquiring whether or not the Evo HT2 would allow for emissions equipment to be removed from your truck, and the answer is of course not. The reality of living in 2022 is no reputable company will offer delete tuning anymore, and they haven’t for many years. With forward thinking companies like Edge Products writing tunes that are clean and work with your emissions equipment instead of against it, there is no need to remove any parts from your truck to reliably make power. Deleting a truck to add performance is an outdated way of doing things, and it’s incredibly illegal, not to mention dangerous, since most tuners writing delete tunes don’t actually know what they’re doing and often times will leave your truck running worse than before with many factory safeguards removed.

It’s time to shift our mindset into the 21st century and embrace the clean diesel movement, and I’m glad companies like Edge Products are still developing tunes for these newer trucks despite the hurdles of an impossible-to-flash ECM. Tuning your L5P is now easier than ever, and I am blown away by how much power and how many features they pack into such a tiny device for such an affordable price point.

Never Say Never

When you make a bold claim that includes absolute statements like “impossible” and “never” and then publish it to the world, you’d better be pretty confident with what you’re saying. We may never know if the original author of the post making the claim that the L5P will never be tuned has heard the news or not, but at the end of the day, the development by Edge will benefit the industry as a whole. As time goes on, OEM manufacturers will continue to tighten their security measures in an attempt to prevent aftermarket re-flashing, but the performance industry continues to evolve and thrive, and this new technology can perhaps be used in other vehicles that are (currently) impossible to tune. If you ask me, the future is looking bright.