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Best AFM Disabler – [Top 6] Reviews & Buying Guide 2021

Absolutely devastated with the performance of your AFM enabled GM V8 workhorse? Looking for a way to disable it altogether? You have come to the right place. Today we are going to look at some of the best AFM disablers you can buy for your money.

Not only that, but we also included a handy dandy buyer’s guide and a few FAQs to get you all well-informed. Read on and decide on which is the right AFM disabler for you.

In a hurry? Just look at our top 3 picks. You won't regret!




Editor's Rating







6 Best AFM Disabler Reviews 

So, we are going to start off our reviews list with the best of the best. From there, we will continue down to other modules that should prove handy. Read right on!

1.Range Technology Active Fuel Management Disable Device (Blue)


Looking to keep your GM V8 at V8 mode all the time? Do not like that droning noise from the engine when in 4 cylinder mode? Let us take a look at the Active Fuel Management Disable Device (Blue) from Range Technology.

Just plug it in, and you have a fully running V8 engine at all times. The installation process is instantaneous and requires no tools whatsoever. Since this is plug and play, we do not need to go for any engine modifications of any sort.

The best part? This unit does not reprogram the manufacturer ECU. Thus, we can turn it off when we do not need it, and with that, remove all traces of modifications. The ECU unit goes back to what it was before.

So we installed this unit into the OBD II port of our truck. Got full V8 mode. What does that translate to? Well, now we have the full V8 power at all times. We also get the full-throttle response and a much more consistent power delivery curve. The full powerband you would get from a naturally aspirated V8 engine.

This is especially important because most of us use our GM trucks as true workhorses. Those four disabled cylinders come in handy for high workload scenarios such as for towing, working off-road, moving under icy or snowy conditions, or even for our daily commute.

One word of caution, you should remove the device from the vehicle if the vehicle is not driven as often. Else you are likely to end up with a depleted battery. We especially love the fact that it eliminates that low drum noise that comes from using just four cylinders. That alone would be the selling factor for most people.

Hence, if you are looking for a smoother ride with the full power potential from the GM’s V8, this is the best AFM disabler hands down.


  • Enables full V8 operation
  • Does not modify the stock ECU program
  • No traces of mods when removed
  • Plug and play


  • Should not leave it in the car when it is not in use

2.DiabloSport S1000 Sprint Car Fuel Management Module


Cannot get rid of that lag problem in your Chevy? The fuel efficiency feels like a joke with excessive consumption? This S1000 Sprint Car Fuel Management Module from DiabloSport might just be the solution for you.

Most of us would have noticed that annoying lag problem by now. This persists, especially in those V8s with some sort of fuel management, be it AFM or other gauged systems. This gets worse if the vehicle comes with that start-stop feature.

On paper, yes, it does save some fuel, but it translates to poor engine performance in reality. So what is the solution? Bypassing the fuel management system. Most of these fuel management systems are controlled by a computer, and that is where the DiabloSport S1000 comes in.

The DiabloSport S1000 bypasses the computer-controlled fuel management system, re-enabling the remaining four cylinders of your V8 engine, eliminating all lag from the engine. Mind you, the lag we are talking about is not turbo lag. This lag is between when you press down on the pedals, and the engine revs up.

You notice the difference right away. The downshifts are much smoother, the drive is much smoother. You get more throttle response off the lights. And you want to keep your engine in V8 mode at all times and curb the excessive oil leakage by the built-in fuel management systems. This product makes that possible.


  • Smooth engine performance right from the get-go
  • Eliminates engine lag
  • Eliminates engine lagSmoother downshifts
  • Built-in fuel management systems


  • It may cause you to fail your local emission laws

3.Range Technology Start/Stop Disable Device Blue (BLUE)


Remember Range technology from one of our previous reviews? Of course, you do. This time we are presenting another one of their offerings, this time, it disables the annoying start/stop feature in your vehicle. Let us get right into it. The start/stop feature, for the average user, may seem like a godsend.

Sure, it might be alright for city commutes, where your daily use of the vehicle only encompasses the drive to and from your workplace. For highways, the start/stop feature is not worth it.

Something like this becomes more relevant for those of us who use heavy-duty work vehicles. The start/stop feature in a work vehicle is practical. Well, it would have been much better if it were just useless. But the start/stop feature does another annoying thing, and that is disabling some of the cylinders in the truck.

Thus, towing capabilities become cumbersome, so does hitting the trails. So how do we get around this start/stop feature? That is where this device from Range technology comes in. Simply plug it in, and it will electronically disable the start/stop system.

Disable is just a term, it would be easier to think of it as bypassing some of your truck’s systems. Most of those are computer-controlled. Thus, it just becomes a thing to simply bypass and get along with the job. And that is what this device from Range Technology does.

We get a smoother power delivery curve. The full power of your engine whenever you need it.


  • Bypass the start/stop feature
  • Smoother power delivery curve
  • Plug and play solution
  • Electronically controlled


  • Will not work with all vehicles

4.DiabloSport S1000D DCX Sprint OBDII Plug-In Tuning


Got a vehicle with the new Multi-Displacement System feature (or MDS for short)? Not satisfied with the power output? The S1000D DCX Sprint from DiabloSport may just have the solution for you. Let us take a peek.

But we must first understand what the Multi-Displacement System is. What it essentially does is that it shuts down 4 of the 8 cylinders in your V8 engine in order to conserve fuel. In theory, it makes sense, shutting down half the engine should save some fuel.

In reality, however, other than the claimed increase in fuel efficiency, there is a significant hindrance to the power displacement of your Hemi engine. Other than that, a significant number of consumers complained about their engine “jerking” uncontrollably when driving to engage this MDS mode.

So what now? Well, if you are looking to disable that Multi-Displacement System on your Hemi, we recommend checking out this plug-in solution from DiabloSport. Simply plug it in, and it should disable the onboard Multi-Displacement System.

The DiabloSport module does not disable it, rather it bypasses the system, giving you back the control over your engine. It completely eliminates the input lag and the rather annoying drone noise caused by the MDS activation.

This is compatible with most Hemi engines with MDS. Be sure to check the manufacturer’s site for compatibility. The only complaint we have about this is that it is going to put a significant strain on your battery. So we recommend unplugging the module when the vehicle is not in use.


  • Bypasses the MDS system
  • Eliminates input lag
  • Eliminates that four-cylinder droning noise
  • Plug and play solution


  • Might deplete your battery if left unchecked

5.DiabloSport M1000X Marathon OBDII Plug-in Tuning Module


So far, we have looked at methods we could use to bypass the onboard AFM systems or disable them altogether. Perhaps you are looking for something that will further improve the performance of the built-in AFM system. We have you covered. Introducing the M1000X Marathon from DiabloSport.

We know by now how the AFM or the Active fuel management system works. What it does and how it increases the efficiency by disabling four cylinders from your V8 engine. From the manufacturer, the active fuel management system stays on for around 35 percent of the time.

Plug in this M1000X Marathon module, and we can see a boost in the AFM range to up to 80 percent. Neat, right? You can save up a lot on fuel, especially if your daily commute is within the city limits. This module is compatible with all GM models that feature the Active Fuel Management system.

Simply plug it into the OBD II port under the dashboard of your GM, and you will have a better performing AFM system from the next time you drive. Four of the cylinders immediately disengage, and you can see AFM turned on for around eighty percent of the engine on time.

Hence, you can save quite a hefty chunk on your gas bills your daily commute brings in. But before making that purchase leap, do check the manufacturer's website for compatibility with your vehicle.


  • Instant AFM boost
  • Plug and play system
  • Reduction in gas bills
  • AFM uptime increased to 80 percent


  • Not compatible with all vehicles

6.Range Technology MDS Manager for Dodge and Chrysler


We begin this review with a warning. This module is one of the most cloned ones we have on our list. Exercise caution and buy from authorized dealers only. We recommend that you procure this from the manufacturer directly, if possible.

Previously, we featured an MDS bypass module from DiabloSport. This time around, we saved the best for the last. Let us now look into an MDS bypass module from the household brand Range Technology.

These guys started out with developing active fuel bypass modules for GM V8s. And now they have got a module for the Hemi users out there. A refreshing change. You can be sure we were eager to get our hands on this one.

So what is different? Nothing, really. This is the same plug and play system that bypasses the internal computerized controls without outright disabling them. So you can unplug the module and remove all traces of your modifications. Neat.


  • The price is really good
  • Is bound to last a long time
  • Able to bypass ICC without disabling them
  • Easy to use , Easiest to install


  • There are lots of fakes out there

Things to Consider before Buying AFM Disabler

Okay, so, we have taken a look at several different variants of AFM disablers in the market. We have seen what they can do and what they cannot. These AFM disablers work only for GM’s trademarked AFM feature.

So perhaps you have decided to pick one up for yourself. Let us take a peek at the things you should look out for and what an AFM disabler actually is.

AFM Disabler

In the most basic terms, it is an electronic device that you can plug into the OBD-II port, which is situated under the dashboard of your GM vehicle. The unit resembles those USB dongles you would get with a wireless mouse.

It simply prevents the onboard computer from switching the system over to the proprietary four-cylinder mode. Quite simply, would you not agree? We do not have to go through the mess of taking the entire engine apart to install one of those AFM delete kits.

Check Engine Compatibility

AFM comes in the following GM engines only. The engines are 5.3-liter small-block V8, 3.9 liter V6, Vortec MAX 6.0 liter V8, and Vortec 5.3 liter V8.

Identifying the AFM Components

Now, perhaps your engine is not listed above. But you are sure that there is some level of cylinder disengagement. So it cannot hurt to go for a simple check, eh? Let us begin.

  • Engine Valley Cover

Engines that come with AFM have a rather distinct cover. The difference is that these covers come with an electrical connecter on the backside. Another way to identify an AFM cover is by looking at its underside. If the underside has solenoids attached, you can be sure your engine comes with AFM.

For future reference, these AFM covers have names. It is called the Lifter Oil Manifold Assembly, or LOMA for short.

  •  The Engine Block

The next thing we ought to check out is the engine block. All of GM’s fourth-generation engine blocks come with oil passages and AFM towers cast right into the block. But that is not the indicator, because often, these towers are only functional on the engines that GM serve up with AFM functions.

Which means there are blocks with AFM parts built-in, but no AFM functionality. Thus, we go look for other indicators.

  • Cylinder Lifters

AFM enabled GM engines typically make use of cylinders numbered 1, 4, 6, and 7. These cylinders make use of special lifters, and thus, they are taller. They also have specialized oil holes. AFM-enabled engines also make use of a pressure release valve on the oil pan.

To further reduce fuel consumption, the use of a specialized camshaft and a high volume oil pump can also be seen.

  • Oil Pressure Release Valve

The valve can be found attached to the rail on the oil pan. This valve helps release some of that oil pressure, which would otherwise negatively affect the performance of the AFM components. The original valve sprayed oils onto the cylinder inner walls. This increases oil consumption.

From the 2010-year models onwards, GM added a deflector to redirect this oil spray into the pan (parts number: NAL-12639759). So our primary indicator would be the valve itself that is parts number W0133-2574213.

Check Your Drivetrain

So you have discovered that your engine is compatible with an AFM disabler. The last thing for us to check would be the drivetrain. And the disabler should only be used if the drive train is in good condition.

Check Your Local Laws

Check with your local laws and regulations. There are a lot of parts that are not legalized for use in the state of California. And there may be other states with similar laws and regulations. Follow all of the above and get yourself the best AFM disabler that perfectly suits your needs.

How Does AFM Work?

Not everyone wants to push their engine’s capacity to the maximum every now and then. You do? Well, you may need it at times, but not always. Moreover, always keeping it at the peak causes the consumption of a good amount of fuel, which can be saved by an AFM.

Now comes the question - how does AFM work? AFM basically keeps the vehicle at a level of functionality where it doesn't allow it to use the entire power of the engine. To know how it works, read the whole write-up.

Why AFM?

One of the common scenarios of the vehicles that we see around us is that they often render more power compared to the requirement of an individual on the road. There are drivers who own rides with V-8 under the hood, but they're using them for a regular drive or hauling.

Surprisingly, some use trucks with that much power just for towing. But the truth is not even half of the power of that V8 is being actually used. In the long run, it causes the engine to go on a falling curve of efficiency.

Ultimately, it leads to nothing like an optimal fuel economy. But this is where the Active Fuel Management jumps in to change the game. It uses only 50% engine cylinders under certain driving situations and saves you fuel.

For example, in case you’re on the highway cruising, the AFM can save a good amount of gas on that run. But whenever you decide to boost your speed, it will switch to the regular mode. The ideal situations where you might need power to the fullest are accelerating, hauling, or climbing.


If you’re new to the term Active Fuel Management, don’t worry, you’ll love the whole mechanism. It saves fuel and keeps the performance at an optimum level at the same time. Moreover, walking back to the high-performance mode is also possible quite instantly with it.

Engaging Elements

For proper functionality, AFM depends on two prior elements. The first one is a combination of hydraulic valves. The second one is the software for switching cylinders off when you won’t need to use the full power of your engine.

Stage of Functionality

AFM basically works in two stages of functionality. On the first stage, it keeps the power to a lower level by shutting off 50% cylinders. This is when you don't need to utilize the total power of your engine. On the other stage, where you need a power-up, the AFM system re-engages the cylinders that were inactive.

When you're in light-driving conditions, AFM keeps only four of the cylinders activated or functional out of eight. By the way, that's on engines which has eight cylinders.

If your one has six, then the AFM will keep only three of them activated. But whenever you want to get back to the regular mode, it will reactivate all the cylinders seamlessly.

Cylinder Activation Ratio and Fuel Efficiency Level 

Active Fuel Management keeps the engine in a way where it will get only the required amount of power that you need to keep your ride moving. That power will just be a fraction of the total power.

But how does the AFM keep it that way? Actually, it stops the fuel from going to 50% cylinders (4 out of 8 / 3 out of 6). It does that by using a solenoid system to collapse the valve lifters that ultimately minimize the pumping losses.

In the end, it ends in improved fuel efficiency. It’s said that the AFM can push fuel economy to a level of 12%, and that's without causing any downfall to the performance.

How to Disable AFM?

Not everyone is a fan of AFM, and they have their own reasons for that. To be honest, these reasons are nothing that can be ignored too.

Reasons for Disablement

The first one is some of the drivers don’t want to compromise with the power. They want full power for the whole time when they’re rolling in the street.

And the second one is some people consider the four-cylinder sound annoying. But that’s applicable mostly for them who have a louder aftermarket exhaust. The last one is AFM lifters come with a possibility of failing under certain circumstances, and oil consumption can be an issue then.

Ways to Disable AFM

Now, let’s jump to the ways to get the AFM disabled. To do that, you have two different options. One of them is AFM disabler, and the other one is AFM Delete Kit. There's more to it, and you'll find all below.

  • AFM Disabler

The first option is the installation of an AFM disabler. For that, you need is to buy a disabler at first, plug it into the OBD-II port under the dashboard, confirm its activation, and Voila!

  • AFM Delete Kit

The next one is installing an AFM Delete Kit. But an AFM Delete Kit shall be used under two scenarios. First, when there’s a failure of an AFM lifter. Second, when you’re going for the performance upgrades. Here, the AFM components get replaced with standard parts.

But for installing an AFM Delete Kit, there are certain things you need to make sure. They’re as the following ones –

  • A non-AFM camshaft is mandatory.
  • Turning the AFM system off. You can do that with a computer program or can go for custom tuning.
  • Get the pressure relief valve plugged in the oil pan.
  • Go for a standard-volume oil pump.

If you say, ‘How does AFM work?’, I think you have all the answers now. Having an AFM has its own certain and specific advantage. That doesn’t mean all the drivers will go for it or will consider it as the best option. But you have the full freedom to have an alternative like disabling the AFM.

So, if you love to keep your V8 in the regular shape without worrying about how much fuel you need to save, you can go for an AFM disabler or an AFM Delete Kit.


There are no different types of AFM disablers. Although there are AFM delete kits, they are very, very different from these AFM disablers. They are a topic for another day. But in short, we recommend that you invest in AFM disablers instead of one of those AFM delete kits.

The installation process is completely plug-and-play. These devices do not flash the factory ECU software, so you can always revert back to AFM mode. Simply remove the AFM disabler, and you are back.

Frequently Asked Questions (FAQs)

Below are the most commonly asked queries regarding the best AFM disablers:

  • What are AFM disablers?

AFM disablers are essentially miniature tools that plug into the diagnostic port of your GM vehicle. They have a software that allows the engines of these V6 or V8 vehicles to run at full cylinder mode at all times.

Rather than disabling, it is easier to think of it as bypassing the Active Fuel Management system altogether, thereby preventing it from dropping cylinders whenever it wants.

  • Does disabling AFM aid lifters in any way?

No, it does not. When we do or add an AFM delete kit, it does not save us money. Or rather, it does not save us any money when compared to replacing the AFM valve filters all together with new units.

  • Why did my AFM lifter fail?

It is almost always a fault in the oil pressure or control. The activation or deactivation of the AFM in your vehicle is determined by the VLOM or the extended Valve Lifter Oil Manifold. It basically exerts control over the flow engine oil into the intake of the built-in active fuel management system and the exhaust valve lifters.We hava a thorough discussion on AFM lifter failure , check it out.

  • Does disabling the AFM reduce fuel consumption?

A very common misconception. Disabling the AFM does NOT reduce oil consumption. The purpose of disabling the AFM is to get our other cylinders running at all times. Therefore, that basically means additional fuel will be consumed in the same period of time when compared to keeping the AFM on.

Therefore, no, disabling the AFM does not reduce fuel consumption; rather, it will increase the fuel consumption as we are enabling the otherwise disabled cylinders.

  • What engines come with this AFM?

AFM can be found on GM engines only. The engines are 5.3-liter small-block V8, 3.9 liter V6, Vortec MAX 6.0 liter V8, and Vortec 5.3 liter V8.

Final Words

And so there we have it. Some of the best AFM disabler units you can buy for your hard-earned money. Our nomination for the finest AFM disabler goes to the Active Fuel Management Disable Device (Blue) from Range Technology. We hope you learned a fair bit about AFM disablers from this article. Happy purchasing!

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