How to Prevent AFM Lifter Failure

Posted by Robert McJannett on

How to Prevent AFM Lifter Failure: Symptoms and Causes

Active Fuel Management (AFM) was a system GM engineers developed back in 2005 to help improve the fuel mileage from some of their V6 and V8 engine applications. AFM shuts off half of your engines cylinders to operate at a reduced power level to reduce fuel consumption when running in low load and cruise situations. However, this does have some drawbacks, as it can cause AFM lifter failure and lead to excessive oil consumption. In this article, we’ll cover the causes of AFM lifter failure, how to prevent it, and how to disable AFM without a tune if it becomes necessary.


How the AFM System Works

Active Fuel Management (AFM) system works by shutting off half of your engine cylinders, so your car can operate at a reduced power level and lower fuel consumption in low load and cruising driving situations. Studies show that AFM can help improve fuel mileage by 5 to 7%.

The AFM system has many internal working mechanisms required to turn on and off thousands of times. This can cause severe wear and eventually lead to AFM lifter failure.


What are AFM Lifter Failure Symptoms?

Faulty AFM lifters can cause severe damage to your car, so it is crucial to spot the failure early. Some customers experience “shuddering” as AFM/DFM vehicles switch between running on half or all cylinders. Over time GM’s troublesome valve lifters tasked with activating and deactivating constantly can cause costly future repairs. Some of the symptoms of AFM lifter failure are:

1. Difficulty Downshifting

If you experience difficulty downshifting when driving, your car’s AFM lifters might be damaged. It is vital to take quick action once you notice this, as this can damage important parts of the vehicle, including the clutch, flywheel, and even the entire transmission system.

2. Low Engine Power

Typically, your engine should deliver optimum power when needed, but if the engine fails to provide full power, it could be a symptom of AFM lifter failure. While this problem can also indicate problems related to engine timing issues or the cylinder misfiring, you should not rule out a case of AFM lifter failure.

3. Engine and transmission "shudder"

If your vehicle is jerking from side to side when you accelerate, without any prior warning, it can be a case of AFM lifter failure. This could be a major road hazard and can cause major damage if not rectified early enough.

4. Vehicle Hesitation on Acceleration

If you notice your car hesitates when accelerating, it could be a sign of AFM lifter failure. It could be a symptom of other problems like too high temperatures or a mass airflow sensor failure. Whatever the cause may be, do not ignore it and get it checked out as soon as possible.

5. Sudden Stalling

A car engine suddenly staling without warning is a common symptom of AFM lifter failure. This, coupled with engine grinding, is extremely dangerous, as the vehicle can stall at any time. This can be very dangerous in some situations, like the car suddenly stalling in the middle of the road while driving, leading to a loss of control. If you notice this symptom, get your car checked out immediately.

Other symptoms include: Excessive oil consumption, Premature wear to the valve train, Exhaust drone and in some extreme cases, complete engine failure.


What Are the Causes of AFM Lifter Failure?

Apart from knowing the symptoms of AFM lifter failure and how it can pose a potential road hazard if left unfixed, you should also know the causes of this problem. Some of the problems that have been identified include:

1. Low Oil Levels

Like every other component in your vehicle’s engine, the AFM lifter needs proper lubrication, and a lack of oil to provide the required lubrication can cause serious problems. If your car’s oil levels are low for a while, it can cause AFM lifter failure as excessive friction will be created in the engine’s moving parts, causing indents in the oil seals and eventually causing the lifters to fail.

2. Poor Quality Oil

One of the causes of AFM lifter failure is low-quality oil. If you use a bad quality oil in your vehicle for a long time, it can cause complete AFM lifter collapse and require you to replace multiple parts in the engine and possibly reroute the stock tanks.

3. General Wear and Tear

Regular use causes the engine components to break down over time slowly, and if this wear and tear are not taken care of, there will be an eventual AFM lifter failure.


How Do I Prevent AFM Lifter Failure?

To prevent AFM lifter failure and further damage to your car’s engine, there are a few steps you can take. Some of them are:

1. Use High-Quality Oil in Your Vehicle

While you don’t have to break the bank and buy the most expensive oil on the market, ensure the oil you buy is recommended by the manufacturer or very closely suited to your engine. This can help eliminate AFM lifter failure.

2. Service Your Car Regularly

An excellent way to combat regular wear and tear that eventually causes AFM lifter failure is to service your vehicle regularly by taking it to the mechanic. This will nip any developing problems in the bud and can even help to prevent unknown problems.

3. Use an AFM Disabler

AFM lifter failure is primarily caused by the AFM system preventing half your engine’s cylinders from working to manage fuel consumption. By disabling the AFM so that it doesn’t work as often, you can significantly reduce the risk of AFM lifter failure. Activating the AFM disabler is very easy and gives the bonus of ensuring that the lifters will last much longer.

Range Technology AFM/DFM Disabler For General Motors Vehicles

Luckily for the GM owners everywhere, there is aftermarket support here that can help prevent some of these expensive repairs and failure modes. Range Technology of Ogden, UT developed a simple to install, end-all cure-all, for the troublesome Active and Dynamic Fuel Management systems. Their AFM/DFM Disabler module will simply plug direct into your vehicles OBD-II diagnostic port under the dash, automatically detecting the AFM/DFM system and disabling it for good. No programming required, no permanent changes to the vehicle, and best of all, no traces left on the PCM should you still be under a factory warranty. The AFM/DFM Disabler can be unplugged returning the vehicle to factory function in seconds and can be reinstalled just as easily once dealer warranty work is completed.

Range Technology says its disabler will prevent the “shuddering” that some customers experience as AFM/DFM vehicles switch between running on half or all cylinders.” The company also says the module can save the owner money on “costly future repairs,” as GM’s “troublesome valve lifters will no longer be tasked with activating and deactivating constantly.”

Looking for an AFM/DFM Disabler in Canada?

Just about every applicable GM application from 2007-2020 is covered by the Range Technology module with your choice of LED colours, the popular Blue or Red, with Green also available. Best of all the module can be moved from one vehicle to another at any time. Range Technology’s plug-in disabler works with older General Motors vehicles that still have AFM and new ones that use DFM. It will work with all GM vehicles with a V6 or V8 engine with AFM or DFM, including cars, SUVs and the popular Chevrolet Silverado and GMC Sierra pickup trucks. 


Range Technology AFM/DFM Disabler for GM Vehicles in Canada from Performance Improvements

The AFM/DFM Disabler is inexpensive and requires no time or effort by the owner to be installed. There is no learning curve or homework required.

Plug in the device, wait for the LED’s to power on, start your vehicle and drive.

It’s truly a plug and play resolution to potentially very costly repairs.


Other AFM Links


Share this post

← Older Post Newer Post →