No doubt, the active fuel management (AFM) system is one of GM’s technologies that distinguish the brand in the automotive industry. Of course, people want vehicles with improved gas mileage.
Hence, the AFM system makes GM’s Chevy a perfect car for such a purpose. However, the system comes with a couple of drawbacks that make a lot of users think twice.
Reason enough, some Chevy owners consider deleting or disabling the AFM system to be the way out. First of all, let’s see how the system works, it’s a major problem, and then finding how to disable AFM without a tune will be easier.
What Is Active Fuel Management System(AFM)?
In the simplest possible terms, the Active Fuel Management System is a trademark feature of GM vehicles whereby it automatically shuts down half the cylinders of their v6 or v8 engines, which can theoretically to save fuel.
While it does work in most cases, it is not without its problems. The two main problems are that this system leaks oil into the engine pan and that four or three active cylinder engine noise is… Well, annoying.
So, while you might save fuel through the system, you also end up losing fuel, courtesy of the leaks. So, most people seek ways to patch this up, so to speak.
How does AFM System Works?
The concept behind AFM is that high-powered engines are very inefficient whenever high-demand power is not necessary. Experts estimate that most V8 and V6 engines only require about 25% of the engine’s total power for everyday driving.
Instead of installing a more efficient and smaller engine that might tow capacity and acceleration, the AFM technology deactivates unnecessary cylinders when needed to improve efficiency.
Cylinder deactivation begins by turning off the intake and exhaust valves. The process is done via a solenoid control valve assembly, signaled via pressurized oil to activate and deactivate hydraulic roller lifters.
The filters are the ones that physically close and open the intake and exhaust valves. When both valves are closed, any exhaust gas that remains in the cylinders expands in one cylinder as it decompresses in the other one.
The compression helps in maintaining power in low-demand situations. When more power is needed, the exhaust valve reopens to discharge the old exhaust gas to allow in a new cycle.
The AFM system requires considerable electronic control because of the extreme precision needed to create a seamless operation.
Several factors, including engine emission controls, advancements in-vehicle system computing power, and Electronic Throttle Control, have contributed to the successful assimilation of the AFM technology in modern vehicles.
What Engines Have AFM?
AFM is equipped on various Vortec engines. However, you need to look into your specific engine code as AFM is not used in every single engine.
- 5.3 Vortec: LY5, LC9, LH6, LMG, LS4
- 6.0 Vortec: L76, L77, LFA, LZ1
- 6.2 Vortec: L94, L99
- 3.9 Vortec: LZ8
- 4.3L EcoTec3 engines
- 5.3L EcoTec3 engines
- 6.2L EcoTec3 engines
- 3.6L V6 LGX
- 3.0L V6 LGW
- 4.2L V8 LTA
AFM Lifter Failure Symptoms
Although the active fuel management operation plays a vital role in ensuring a better fuel economy, its impacts on the other hand, can be detrimental to the AFM lifter.
The regular deactivation and reactivation of half of the cylinders in the vehicle can result in the AFM lifter failure when you least expect it. This is immediately followed by a couple of symptoms. Some of the AFM failure symptoms include:
#1. Low engine power.
Since the AFM works by disengaging some cylinders and reactivating the same, it minimizes the pressure on the engine and suddenly puts more pressure when more power is needed.
Constantly engaging this process can affect engine power over time. So, if you discover that your car’s engine operates at low power levels, you most likely have an AFM lifter failure.
#2. Downshifting difficulty.
Again, the transmission system is engaged in the AFM operations, hence, the tendency to experience a transmission system issue. Usually, the problem is with the downshifting operation, as you may experience difficulty in this area.
#3. Hesitation during acceleration.
Although there are other faults that can cause a vehicle to hesitate during acceleration, an AFM lifter failure may not be entirely blameless in some cases. So, you may want to check that out if you’re experiencing this challenge at the moment.
#4. Engine stalling.
Also, although engine stalling can be traceable to different causes like an empty gas tank, bad fuel pump, low fuel pressure, etc., however, the AFM lifter failure can also be a culprit for AFM-equipped vehicles.
#5. Check Engine light display.
Of course, any malfunction that tampers with the normal operations of a vehicle’s engine is just a “blink of an eye” away from illuminating the Check Engine light. So, this is yet another of the numerous 5.3 lifter failure symptoms you may encounter.
What Causes Lifter Failure?
Identifying the causes of lifter failure can help you avert its occurrence at any time. This will save you the stress (energy) and money that fixing the component will demand. So, some of the causes of AFM lifter failure include the following.
#1. Wear and tear.
Virtually all vehicle components are susceptible to wear and tear through constant usage over time.
For instance, the active fuel management operation engages and disengages several internal mechanisms over and again. Consequently, this can cause increased wear and tear.
So, failure to engage in regular maintenance can result in the damage of various components and eventually lead to the AFM lifter failure.
#2. Poor oil quality.
Oil plays a vital role in a vehicle’s engine operations. However, using the recommended oil for your car is a necessity. Therefore, using engine oil with poor quality can pose a serious threat to the engine and eventually result in damage to the AFM lifter.
#3. Low oil levels.
Running on low oil levels is an experience you must avoid at all costs. This is because some components, including the AFM lifter, require adequate lubrication to function optimally.
Therefore, running on low oil levels will result in friction between the engine’s moving parts, and this can collapse the AFM lifter.
Why Would You Want To Disable AFM?
Even though the main goal of the AFM is to reduce your fuel consumption, which in the end would save you some money, but there are some who do not particularly care for it and would, therefore, want to disable it completely or delete the setting from their car.
Maximum Power
The first reason why people would want to disable it is to make sure they have maximum power at all times.
If the car is conserving fuel, then you will not be able to make full use of the vehicle, and you might be someone who enjoys driving a certain type of why. So, you wouldn’t want
the AFM is stopping you.
For Noise Reduction
Another reason why many people want to disable it is because of how sensitive they are to sound. When the engine is running on four cylinders, you will hear a slight noise coming from your car.
Some people can completely tune it out while others can’t stand it at all. If you are the latter, then this will annoy you a lot.
How to Disable AFM?
The minor drawbacks discussed above may make you want to disable or turn off active fuel management.
There are two ways to delete or disable active fuel management on your vehicle. One of them is installing an AFM delete kit, and the other is installing an AFM disabler.
Here is what you should know about the process:
Install an AFM Delete Kit
An AFM Delete Kit is highly recommended when performing upgrades or when an AFM filter fails. The AFM delete kit replaces the AFM components with standard parts.
During the installation of the AFM delete kit:
- Upgrade to a non-AFM camshaft because the cam lobes in the four AFM cylinders are ground differently. Your engine will have at least 25 fewer pounds of compression in the four cylinders, which might result in a misfire code.
- Turn off the AFM system using custom tuning or a computer programmer.
- Plugging the pressure relief valve in the oil pan is recommended.
- Switching to a standard-volume oil pump is recommended.
How to Disable AFM Without a Tune?
You can disable the AFM without the tuning using the following methods:
#1. Use an AFM Disabler.
An AFM Disabler is a functional electronic device that plugs into the OBD-II port under the dashboard. The device prevents your vehicle’s computer from switching over to four-cylinder mode.
The technique is a simple and effective way of turning off the Active Fuel Management System and improving exhaust sound.
You should only use an AFM Disabler if the valve train is in excellent working condition. It’s worth noting that engines with an AFM system use a high-volume oil pump; therefore, the excess oil is no longer required when you remove the AFM system.
The extra oil will be pushed out of the pressure relief valve into the oil pan. This sprays oil on the bottom of the cylinder walls and can cause oil burning, especially in engines with a high RPM.
If you’ve installed the AFM delete kit but cannot access an AFM deleter programmer, a disabler may still be a viable option. To use the option, you will need to leave the AFM solenoid pack connected to ensure no codes are thrown.
You can reuse the original valley cover or use a non-AFM valley cover, leave the harness connected, and tuck the solenoid pack away.
#2. Disconnect the Brake Booster Vacuum Sensor.
You can disable the AFM by disconnecting the brake booster vacuum sensor. However, this method does not work for all vehicles.
Although it’s not a fool-proof plan, it will get the AFM disabled. You might need to scan the car sometimes to check if your car is having issues after disabling AFM.
Benefits of Disabling AFM with a Scan Tool
- Full Cylinder Operation: The primary benefit of disabling AFM with a scan tool is that your engine will always run on all cylinders. This eliminates the jerky transition between four-cylinder and eight-cylinder operation, resulting in a smoother driving experience.
- Improved Performance: For drivers who regularly tow, haul, or drive in performance-demanding conditions, disabling AFM can provide a noticeable improvement in power delivery and throttle response.
- More Control Over Engine Settings: Using a scan tool provides the flexibility to adjust more than just the AFM settings. You can also modify other engine parameters, allowing for a more customized driving experience.
How Do I Prevent AFM Lifter Failure?
Irrespective of the tendencies for AFM lifter failure to occur, there are a few measures that can help you prevent the problem from surfacing in the first place. Some of the measures on how to prevent AFM lifter failure include the following.
#1. Regular vehicle maintenance.
A regular vehicle maintenance culture can help to prevent several problems, including an AFM lifter failure. Therefore, ensure to design a routine for your car servicing.
An expert auto technician can advise you on the interval and help you perform this exercise regularly. With this habit, you can be sure of averting a sudden AFM lifter failure in your car.
#2. High-quality oil usage.
Remember that low oil quality is a culprit to AFM lifter failure. In that case, it is advisable to use the best and most suitable oil for your vehicle in order to prevent the occurrence of AFM lifter failure.
Meanwhile, ensure to consult your car’s manufacturer’s manual or an expert auto mechanic for details on the type of oil you need.
#3. Disable AFM system.
Since the active fuel management operation is a threat to the AFM lifter, it is only ideal to disable the system in order to avoid damage.
When you disable the AFM system, it reduces the tendency for AFM lifter failure since the system doesn’t have to work constantly. Some people even go as far as deleting the AFM completely.
FAQs.
Q: How do I bypass active fuel management?
The active fuel management (AFM) system can be suspended from its regular operation by installing an AFM disabler. This device is designed to trick the vehicle’s ECU into keeping the engine on V8 mode perpetually.
Therefore, the AFM operation will be suspended to enable the engine to operate without half of the cylinders shutting up to reduce performance and improve gas mileage.
This is an ideal solution if you’re currently battling the negative impacts of the AFM system’s operation.
Q: Can AFM be turned off?
Of course, you can turn off AFM in your car. If you’re currently experiencing challenges with the AFM system, simply get a Range Technology AFM disabler and plug it into the car’s OBD II port under the dashboard at the driver’s side.
Once you install the device, it will turn off the AFM system’s operation immediately and keep the engine in V8 mode constantly. In that case, you won’t have to operate on V8 and V4 back and forth until you unplug the disabler.
Q: Can you disable AFM with a programmer?
Yes, you can disable your car’s active fuel management system with an AFM delete programmer. The software is designed to reprogram the electronic control unit and sustain the engine in V8 mode without moving back and forth from V8 to V4.
However, reprogramming your car’s ECU to disable the AFM system’s operation will eventually void the engine’s warranty.
Therefore, applying another approach (installing an AFM disabler) is best because of the vehicle’s engine warranty. You can always unplug the disabler at any time before seeing your dealer.
Q: Is it safe to disable Active Fuel Management?
Yes, it is completely safe to disable the active fuel management (AFM) system’s operation in a car. Besides the reduced fuel consumption, the AFM operation causes more harm than good. It can damage the AFM lifter and other components before you know it.
So, it is advisable to disable or delete the AFM operation and keep your car’s engine in V8 mode constantly. However, it may reverse the car’s fuel economy to standard consumption since the system no longer switches between V8 and V4.
Q: Will disabling AFM void the warranty?
No! Disabling your car’s AFM will not void the engine warranty if you’re contemplating, “Should I disable AFM?” However, it depends on the option you implement. If you reprogram the car’s electronic control unit, it can void the warranty.
Meanwhile, installing the Range Technology AFM disabler will stop the AFM’s operation and still retain the engine warranty.
So, if you are fed up with the active fuel management operation in your car, kindly get an AFM disabler to end the system’s operation as soon as possible. This will surely give you peace of mind.
Final Words
Understanding how to disable AFM without a tune is pretty straightforward. This has been proven in this article. So, you don’t have to panic or carry the regret of buying a car that is fitted with an active fuel management operation.
Most GM car owners have reduced the AFM failure rate by installing the Range Technology AFM disabler.
You too can save yourself the stress of worrying about the negative impacts of the AFM system in your car by using the AFM disabler. This approach is much more preferable than implementing a 5.3 active fuel management delete on your Vortec engine.