Introduction: Understanding Active vs. Dynamic Fuel Management
Gbrenna – Understanding Active vs. Dynamic Fuel Management. Lifters have been having a terrible time for almost twenty years with GM’s Active Fuel Management (AFM) technology. With the release of DFM (Dynamic Fuel Management) in 2019, they built on this technology and made big changes to how it works. This device is also sometimes sold under the name Displacement on Demand (DoD).
AFM only turns off half of an engine’s cylinders, switching it from V8 mode to V4 mode. DFM, on the other hand, has 17 different firing patterns and can turn off up to 6 cylinders in V8 engines in any random order.
AFM and DFM both do the same thing, which is to turn off some engines to save fuel. They do it in very different ways, though. This piece will talk about the technology behind AFM and DFM, how they are different, and the problems with lifters that each type causes.
How AFM Works
Four cylinders can only be turned off by active fuel management: cylinders 1 and 7 on the left bank and cylinders 4 and 6 on the right bank. The ECM turns on AFM and turns off these cylinders because of a mix of messages from the engine. Cylinders 3 and 6 are turned off in V6 engines, which also changes the engine into V4 mode.
Complex oil tubes, solenoids, and special lifters work together to use oil pressure for this process. You should really work hard if you want to learn more about how AFM works on a technical level.
In terms of gear, the lifter oil manifold assembly (LOMA) has oil control valves that turn off for the four cylinders in question. The AFM lifters in these four cylinders are also a little different from the lifters in the other four cylinders.
How DFM Works
Active fuel management was replaced by dynamic fuel management, which is a more advanced method. A third-party business, Tula Technology, actually made the technology behind it so that GM could make AFM better.
When it comes to DFM engines, the oil control valves are built into the engine block, and each of the eight cylinders has its own control valve and lifters. In this case, any of the eight cylinders can be turned off, not just the four that are used in AFM engines.
GM did a test and found that DFM was on more than 60% of the time, while AFM was only on 52% of the time.
Problems Caused by AFM & DFM
The main trouble with active and dynamic fuel management is that they make issues happen. More than half of the time, an engine running on either of these systems has less than all of its cylinders turned on.
In addition, these systems are always turning on and off. Eighty times per second, DFM figures out what “mode” the engine should be in. This means that during a normal driving session, the engine changes modes thousands of times. The constant turning on and off wears down the lifters and other parts inside over time, which leads to stuck lifters, fallen lifters, and other serious issues.
These systems lead to the following issues:
- Failure of a lifter, such as a lifter getting stuck or collapsing,
- Utilizing too much oil
- Hesitations when speeding up
- The clutch jerks and shifts slowly
- Slow reaction from the throttle
- Wear and tear on the valvetrain
- Possible engine failure
Lifter Failure & Oil Consumption
Lifter failure and oil use that is too high are the two most common problems with AFM and DFM.
Camshaft failure is very common after a car has been driven 150,000 miles. But it can happen much faster, and some DFM engines have started to break down after only 30,000 miles. DFM cars have a slightly higher failure rate than AFM engines because 1) the system is used more often and 2) all four cylinders have the hardware, while only half of the cylinders do with AFM engines. The bad news is that lifter failure happens a lot in AFM engines. We think it will happen even more often in DFM engines as they age (DFM came out in 2019 and is still pretty new).
More oil use usually shows up more quickly in cars that are getting close to 60,000 to 80,000 miles. When things go wrong, engines can need one quart of oil every 1,000 miles. The trouble with using too much oil is what can cause the engine to break down in the end. Drivers should always make sure their oil levels are full. If they aren’t, the engine could run out of oil and break down more seriously.
At the end of the day, both AFM and DFM engines will fail their lifters; it’s just a matter of when. It can cost $2,000 to $5,000 to fix, but there are some cheap things you can do to keep your lifters in good shape.
Prevent Problem by Disabling AFM & DFM
Turning these fuel management systems off is the best way to stop a lot of the problems they cause. By disabling them, they won’t be able to turn off valves, so your engine will always be in V8 or V6 mode and your lifters will always be up. Because these systems frequently turn off and on cylinders, they cause problems. To avoid these problems, it is best to leave all cylinders on all the time.
A disabler like our BOOST AFM & DFM Disabler makes this task very simple. It just goes into your OBDII port and starts working right away. It keeps your car in V8/V6 mode all the time, which stops the problems that these systems cause.
This is what our Boost AFM & DFM Disabler can do for you:
- V8/V6 mode Every single time
- Makes it more reliable and helps keep lifters from breaking.
- It improves speed by making the throttle respond faster and with less hesitation.
- Smoother moves and a more enjoyable driving experience all around
- Easy to use—just unplug the gadget and everything is back to normal.
- Reduces problems with oil waste and early valvetrain wear
- The battery life is the best on the market.
Conclusion: Understanding Active vs. Dynamic Fuel Management
Lifters in GM’s Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) systems face significant issues over time. AFM and DFM aim to improve fuel efficiency by turning off certain engine cylinders, but the constant switching of modes stresses the lifters and other components. This frequent switching leads to lifter failures, higher oil consumption, and various performance issues such as sluggish acceleration and poor throttle response. While AFM has been a known problem for nearly two decades, DFM, introduced in 2019, seems to worsen the issue with more frequent changes. Disabling AFM and DFM can help avoid these problems, improving engine reliability and performance.