LMM Duramax Tuner Guide

From 2007–2010, the General Motors/Chevrolet Duramax LMM was one of the top V8 diesel engines on the market. Powering heavy duty trucks, SUVs, and vans, the Duramax LMM is essentially a Duramax LBZ but with some updated emissions equipment. Depending on the year and model, the Duramax LMM makes 250–365 horsepower and 460–660 lb-ft of torque. While this isn’t bad, if you really want to unlock some more horsepower the best mod is a LMM Duramax tuner.

With a tuner, you can easily add 100 horsepower and more than 200 lb-ft of torque in just minutes. Read on to find the best LMM Duramax tuner and everything you need to know about tuning the LMM Duramax diesel.

LMM Duramax Tuner Basics

Of the endless list of mods you could do to your Duramax, a LMM Duramax tuner is one of the most popular. This mod is very cost-effective and does a great job of adding horsepower and torque. Besides plugging in the tuning device, a LMM Duramax tuner requires no hardware modifications, making it incredibly easy to install. In addition, tuners are completely reversible, so if you decide to at any time you can remove it and go completely back to stock like nothing.

The purpose of tuning is primarily to boost horsepower and torque and make the truck more responsive. It also boosts towing power considerably. Pretty much every modified diesel truck will have some kind of tuner attached to it. They are great not just for otherwise stock vehicles, but they can also help get the most out of other mods, like a LMM Duramax downpipe, intake, or new turbocharger.

LMM Duramax tuners work by either rewriting or manipulating signals from the engine control unit (ECU). On modern cars and trucks, pretty much every aspect of the engine and vehicle are controlled by an onboard ECU. This includes boost pressure, air-to-fuel ratios, ignition timing, camshaft timing, fuel pressure, and more. With a tuner, you can change these parameters to increase boost pressure, increase timing advance, crank up the fuel pressure, and alter air-to-fuel ratios. That will add horsepower and torque, making your LMM Duramax a much faster and more capable truck.

Flashback vs PiggyBack Tuners

As far as LMM Duramax tuners go there are two basic kinds: flashback and piggyback tuners. They both accomplish essentially the same goal – working with the ECU to boost power – but they go about it in very different ways. For a while, piggyback tuners were very popular and all the rage. But lately, flash tuners have become the more efficient and reliable tool for tuning.

Let’s start with how piggybacks work. Piggybacks plug into the physical ECU on your truck and manipulate the electronic signals as they come in and out. This allows changes to boost pressure, timing advance, and many other variables. When you purchase a piggyback device it comes preloaded with various tunes, and these generally cannot be adjusted.

The other option is flash tuning. Flash tuners plug into the OBD II plugin under the dashboard instead of the physical ECU itself. Instead of manipulating signals, flash tuners rewrite the engine programming entirely. They don’t just change the signals coming too and from the ECU, but a tuner actually looks at different parameters and tuning tables on their computer and makes more precise adjustments. Some flash tunes can be adjusted after they are loaded onto the car, unlike piggyback units.

For the LMM Duramax, we recommend you use flash tuners. These provide better and more powerful results that are also safer. In addition, the failure rate on flash tuners is much lower than piggybacks. If you plan on adding mods, flash tuning is a must, as your tune can be changed to suit your new mods – unlike on piggybacks.

Duramax Tuning Terminology

One thing we should probably clarify before going any further is tuning terminology. The terms “tune,” “tuning,” “tuning,” and “tuned” are sometimes used interchangeably with each other but they describe slightly different things. Additionally, E-tuning is a blanket term that is also widely used.

• Tune/Map – The file or software that is flashed to your ECU or manipulates it signals
• Tuner – Tuner can refer to either these two things:
  • 1) The person/company setting the engine parameters in the tune file
  • 2) The handheld device used to flash or piggyback your ECU
• Tuning – The process of adjusting the engine’s parameters
• Tuned – A car that has been modified through either a flash or piggyback tuner
• E-Tuning – The process of having one’s car tuned by a tuner through email correspondence

It’s easy to mix these up when you first start learning about the process, so don’t be discouraged. If you ever have a question as to what something means you can always double check here.

LMM Duramax Tuner Benefits

Some of the benefits of an LMM Duramax tuner include:

• 100+ horsepower
• 200+ lb-ft of torque
• Improved power band
• Improved fuel economy
• Increased towing
• Datalogging
• DTC Troubleshooting and Clearing

By far the biggest benefit to adding a LMM Duramax tuner is the big increases in horsepower and torque. Depending on the specific tuner you use, calibration level you select, and the year and model of your Duramax powered vehicle, you can make some serious gains. With a tuner, the LMM Duramax can easily gain 100+ horsepower and 200+ lb-ft of torque like it’s nothing. This makes a significant difference in terms of both acceleration and towing, and really transforms your truck.

In addition to having much better peak power, you’ll also notice a significantly larger overall power band. You’ll make more horsepower earlier and it will hold out for longer, meaning a much improved mid-range. Depending on the tune, you can also see some increases in fuel economy by a few mpg, though the more you take advantage of the newfound power the worse mileage you will ultimately get.

In addition to getting better performance, you can also get tunes that prioritize towing. Considering the primary use of most Heavy Duty trucks is going to be hauling and towing, this is a big deal. Gaining more torque makes towing noticeably easier on the LMM Duramax.

Another advantage of getting a handheld tuner is they allow for data monitoring, data logging, and DTC troubleshooting and clearing. If you want to be able to monitor things like boost pressure and diesel particulate filter (DPF) status, a tuner is a great tool that allows you to do those things. Tuners can also read and clear DTC codes, stopping you from paying a shop or buying another device.

GM Tuning Risks

Now that we’ve talked about the benefits of tuners for the LMM Duramax, it’s important to also acknowledge the risks. Since you are taking your engine out of the factory calibrations you are also getting rid of some of the safeguards GM/Chevy put in place from the factory. Depending on how hard you push your car with modifications and tuners, they can lead to engine damage and potentially engine failure.

This is why it is important to only use reputable tuners that are well reviewed and have made a solid name for themselves in the diesel community. In some cases, your powertrain warranty can be effectively voided if you tune your truck and something happens. As long as you use a good tune you will most likely be fine, but it’s still important to acknowledge the risks.

Edge Insight CTS3 Diesel Monitor

Before getting into our list of top tuners, first let’s talk about the Edge Insight CTS3 diesel monitor for the LMM Duramax. While this is not a tuner, it is a monitor that allows you to view how your engine is performing after you get it tuned. You can monitor things like boost pressure, fuel pressure, air-to-fuel ratios, exhaust gas temperature (EGT), DPF status, and more. You can also use the CTS3 to datalog to do more extensive monitoring and as a DTC reader and clearer.

The CTS3 is a great supplement for any tuned vehicle, and the new monitor is 720p HD and can be attached to the windshield for convenient placement. For those considering going with an EFI Live tuning option (mentioned below), a CTS3 monitor is incredibly helpful for monitoring your engine.

Best Tuner for Duramax LMM

The 3 best tuners for the Duramax LMM are:

• Edge Evolution CTS3
• Bully Dog GT
• EFI Live

1) Edge Evolution CTS3 for LMM Duramax

Price: $745.95

The first recommendation we have is the Edge Evolution CTS3 LMM Duramax Tuner. Edge is the same company that makes the Insight CTS3 diesel monitor that we mentioned, and they are one of the top companies in the diesel tuning market. The CTS3 is the second version of the Evolution tuner, succeeding the CTS2 that was previously the standard.

The Edge Evolution CTS3 has a full 5” color screen with an auto-dimming feature and looks fantastic. It comes pre-loaded with four tunes on it which can make a maximum of 85 horsepower and 200 lb-ft of torque. In addition, independent tuners can also use the Evolution CTS3 as a tuning device, so you can get a custom tune to make even more power. Monitor-wise, the Evolution offers a ton of different custom layouts and parameters to look at, including boost pressure, EGT, DPF regeneration status, and more.

You can also use the Evolution for data-logging, DTC reading and clearing, and it comes with its own windshield mourning bracket. The Evolution monitor is probably the best on the market, except potentially their Insight CTS3, and it looks very high tech and worth the money. The Evolution is one of the pricier options on our list, but you are definitely paying for quality.

2) Bully Dog GT Platinum Tuner for LMM Duramax

Price: $469.00

Next on our list is the Bully Dog GT Platinum LMM Duramax Tuner. Like the Evolution CTS3, Bully Dog is another well known name in the diesel tuning industry. They have several different options for the Duramax LMM, but we suggest the Bully Dog GT Platinum Tuner for the LMM Duramax. The GT Platinum gives you the most value.

The Bully Dog display is much smaller, at just 2.5”, but is still adequate and has all of the same monitoring, data logging, and DTC reading and clearing capabilities as the CTS3. The Bully Dog is going to be a cheaper option than the CTS3 or the EFI Live, and still comes with several pre-loaded tunes. These tunes will make a maximum of 120 horsepower and 250 lb-ft of torque.  However, you cannot utilize custom tuning on the Bully Dog, which does limit it somewhat.

The Bully Dog is a great entry level LMM Duramax tuner, but for those who are looking at doing a lot of custom mods it might not be the best option. Custom tuning is very important if you have a host of aftermarket mods like an intake, downpipe, or bigger turbo. So, if you plan on going those routes in the future you will probably need to get another tuner, making the Bully Dog somewhat of a waste.

3) EFI Live for LMM Duramax

Price: Varies

Our third option is EFI Live for LMM Duramax. EFI Live is one of the most popular options for the Duramax and offers the best custom tuning capabilities. They have a handheld tuning device, called the AutoCal V3, which is what you use to transfer the tune and EFI software to the car. EFI Live is based in New Zealand, but they have had a large following stateside for a number of years.

EFI Live is the best option for doing custom tuning on the car, as it has by far the most support from tuning companies. This is because the software is exceptionally well made and the best on the market for making the most horsepower and torque the most efficiently. Depending on the custom tuner you chose to make your map, you can make as much as 150 horsepower and 250 lb-ft of torque on an otherwise stock vehicle.

Pricewise, EFI Live is going to be a bit more on the expensive side, because you have to buy it with custom tuning. However, it also offers the best software and the most extensive options for your tuner so safely and efficiently makes lots of horsepower and torque. Especially if you plan on doing more modding, going with EFI Live is the best option. You can get new tunes for it after you add more mods, making the device a one-time buy for the life of your truck.

LMM Duramax Tuner Summary

Overall, adding an LMM Duramax tuner is a great way to add horsepower and torque.  Some tunes can even add 2–4 mpg, depending on which calibration you choose. A tuner can completely transform your LMM Duramax from a spirited ride to an absolute monster in just a few minutes. You can add anywhere from 50–150 horsepower and 50–250 lb-ft of torque without any other hardware modifications, making it by far the most cost effective way to mod your Duramax diesel.

We listed three options for LMM Duramax tuners, and all of them are solid. The Edge Evolution CTS3 offers the best monitor and allows for custom tuning. It is a bit on the expensive side, but the monitor is hands down the best. Its competitor the Bully Dog GT Platinum is also a good unit, it is smaller but also less expensive than the CTS3. It does not offer custom tuning, unfortunately, but the preloaded tunes are more powerful than the CTS3. Finally, the top option is EFI Live, as it offers the best software and most tuning capabilities. However, it has to be had with custom tuning and is usually the most expensive option.

Considering a tuner for your LMM Duramax? Let us know which way you’re going in the comments below!