A powerful engine is an excellent car feature, but you do not always need its full power. This is where cylinder deactivation steps in. Cylinder deactivation is the switching off of some of the cylinders on a car’s engine.
For instance, if your car runs on six cylinders, a deactivation could reduce it to three. However, not all vehicles come with this feature. Some users do not want the activation of this feature and sometimes disable it.
- Here’s the quick answer
- How does cylinder deactivation work?
- Can you turn off cylinder deactivation?
- How do you disable cylinder deactivation?
- Does turning off cylinder deactivation help?
- Does cylinder deactivation affect engine life?
- How much can cylinder deactivation increase efficiency?
- How do I bypass cylinder deactivation?
- Do cylinder deactivation systems cause engines to wear out faster?
- Does cylinder deactivation help improve mpg?
- Will disabling the AFM/MDS/VCM void the warranty?
Here’s the quick answer
Yes, you can turn off the cylinder deactivation on your car. However, on most cars, the cylinder deactivation feature can’t be turned off with the flip of a switch. You will have to install an AFM/MDS/VCM disabler or delete kit.
I will dive into further details, but before doing that, it’s important to grasp how cylinder deactivation works and its main role.
Depending on your vehicle’s make, cylinder deactivation can have different names:
- “AFM” stands for Active Fuel Management system and can be found on GM vehicles
- “MDS” stands for Multiple Displacement System and can be found on Jeep/Chrysler/Dodge
- “VCM” stands for Variable Cylinder Management and can be found on Honda/Acura
How does cylinder deactivation work?
Cylinder deactivation, often referred to as AFM/MDS/VCM, is a technology that uses half of the engine’s cylinders during light driving mode to enhance fuel-efficiency without reducing the overall engine performance.
This technology permits the engine to use just half of the cylinders when minimum power is required. However, as soon as the engine requires more power, such as when climbing or accelerating hard, the engine smoothly transits to the full use of all the cylinders.
The deactivation of the cylinders is not triggered by a button but by the car’s in-built system, which detects when the vehicle does not need the extra power produced.
When this occurs, a solenoid system shuts down the valve lifters to lower pumping losses and stops fuel delivery to enhance fuel economy.
Shutting off the valves carrying fuel to the cylinders implies that combustion only takes place in half of the engine; thus, fuel used is reduced.
Can you turn off cylinder deactivation?
The car’s ECU mostly turns on the cylinder deactivation automatically by detecting the engine’s power needs and ensuring smooth transitions from full use to half use of the cylinders.
So, is it possible to turn off this system? Yes, it is possible. However, you can’t outrightly turn it off with a switch or a button, but don’t fret; there are ways to disable it.
You might wonder, why disable it when it reduces fuel consumption? Well, some drivers prefer to have the full power of their engine beneath their feet at all times. The engine roars lovers also do not appreciate the difference in the sounds when the cylinders are deactivated.
A V8 engine working at full capacity makes more vibrant roars than when working on four cylinders – half of its cylinders. The prolonged transition between full and half cylinders places a burden on the engine. Therefore, leaving the system in activation for too long might not be good for your engine.
How do you disable cylinder deactivation?
There are two main methods that allow you to turn off the cylinder deactivation feature of your car:
Install a delete kit
This requires disassembling some components and replacing them with standard engine parts. This technique might require the assistance of an expert, so you do not mess up your engine.
Before installing this kit, ensure to upgrade to a non-AFM/MDS/VCM camshaft to inhibit a misfire code. You will then need to switch off the system via custom tuning or using a programmer.
I would not advise installing an AFM/MDS/VCM delete kit on your own unless you work in the industry. The potential damage that can be caused outweighs the costs of having an expert do it.
Install a disabler
This can be installed by plugging in the device which contains the software into the ODM II port. The disabler prevents the engine from switching to a half-cylinder model by programming the ECU. It can be done within a few steps and does not require disassembling any parts.
This is the easier method many drivers looking to bypass their cylinder deactivation feature choose. It will reprogram the ECU, preventing the car from turning on the cylinder deactivation system.
It is much easier than the other method, where you would have to disassemble and replace some parts.
A system disabler can be installed by someone who has zero mechanical experience.
Does turning off cylinder deactivation help?
If you want to prolong your engine’s life, it definitely can help. Your engine will work at its optimal capacity and not be exposed to the cons of cylinder deactivation.
Some of the disadvantages of a cylinder deactivation system include:
- Excessive oil consumption
- Engine misfires
- Mechanic noises
- Stutter when engaging/disengaging the system
In 2021, GM issued a service bulletin addressing some of its 2020 and 2021 vehicles, that might have a problem with a collapsed lifter, an essential part of the cylinder deactivation system.
The vehicles affected include Cadillac Escalade, Chevrolet Silverado 1500, Chevrolet Suburban, Chevrolet Tahoe, GMC Sierra 1500, and GMC Yukon.
However, turning off the system will not help if you want to save some gas. More on the MPG benefits later.
Does cylinder deactivation affect engine life?
Yes, cylinder deactivation affects the life of your engine. Although modern engines are designed to bear the brunt of the switch between cylinders more effectively, this design is yet to attain a flawless state as the engine still bears the brunt in the long run. How so?
When half of the cylinders are removed from the process of torque generation, hydraulic gaps are created, leading to uneven vibrations within the engine. The appropriate balance of an engine is compromised when made to switch between lesser cylinders.
Why is this? The various engine cylinders are built to adapt to different primary and secondary forces. Thus, when cylinder deactivation is activated, the vibration balance is disrupted.
Cylinder deactivation could lead to the breakdown of the common rail system in extreme cases and result in poor fuel economy, which is in direct opposition to what the system was designed for. The abrupt deactivation of half of the cylinders disables injectors, causing pressure pulses in the common rail system.
How much can cylinder deactivation increase efficiency?
Cylinder deactivation is a system that relies on certain conditions for activation. If the car requires a large amount of power, it will not be triggered as the engine needs to be working at maximum capacity. However, when the vehicle does not need excess power, the system adjusts to this need by reducing the number of cylinders in action.
This transition helps to reduce the amount of fuel consumed when the car is in light driving mode, thus efficiently improving fuel economy.
How do I bypass cylinder deactivation?
Since a simple switch cannot disable cylinder deactivation, you might have to install specific software that programs the ECU of the car not to switch to less cylinder use even when the conditions are fitting. You can use a system disabler or a delete kit.
Do cylinder deactivation systems cause engines to wear out faster?
Yes, cylinder deactivation causes engines to wear out faster. When some cylinders are shut down, they are automatically removed from torque generation; thereby placing more workload on the remaining active piston cylinders.
Like every mechanical component, the more you use the active cylinders, the more you wear them out. If you drive a modern car with this system, it might take a long while to notice the effect on the active cylinders, but in the long run, you might.
Does cylinder deactivation help improve mpg?
Yes, it does help save some gas, but not as much as one would think. Theoretically, if only half of the cylinders are running, you should see a 50% drop in fuel consumption. Wrong! A study by Autosmart shows that fuel savings range from 4 to 10%.
Now comes the question, is it worth buying a truck with a cylinder deactivation system? If you care about the environment and some fuel savings over the ownership of the vehicle, it is worth it. But you need to remember the potential problems that come with such a system.
Will disabling the AFM/MDS/VCM void the warranty?
According to Range Technology, a provider of modules that are able to disable cylinder deactivation systems, their devices won’t void the warranty. As their device is plug-and-play, the vehicle will become stock as soon as you remove it.
However, if you decide to go for a delete kit, which involves replacing some of the engine components, that will definitely void the car’s warranty.
Cylinder deactivation-enabled vehicles assist in reducing fuel economy but might also be unfavorable to your engine over time. Turning it off is a personal choice; if you plan to do so, you can get a system disabler kit or a delete kit.
As discussed already, if you want to impact the environment positively, you should not disable it.
The Hit and Miss Nature of Cylinder Deactivation Systems