How does GM Active Fuel Management work?
General Motors (GM) introduced Active Fuel Management (AFM) as a fuel-saving technology designed to improve the efficiency of their V6 and V8 engines. This system allows certain cylinders in the engine to deactivate under light-load conditions, reducing fuel consumption without compromising performance when full power is needed. In this article, we’ll explore how AFM works, its benefits, and what drivers should know about maintaining vehicles equipped with this technology.
What Is GM Active Fuel Management?
Active Fuel Management is a cylinder deactivation system used in select GM engines. It operates by temporarily disabling half of the engine’s cylinders when the vehicle is cruising or under light load. For example, in a V8 engine, AFM can deactivate four cylinders, effectively turning the engine into a V4. This process is seamless and automatic, ensuring that drivers experience no noticeable change in performance during transitions.
How Does AFM Work?
The AFM system relies on advanced engine control technology and specialized hardware to manage cylinder deactivation. Here’s a step-by-step breakdown of how it works:
- Engine Control Module (ECM): The ECM continuously monitors driving conditions, such as speed, throttle input, and load. When it detects light-load conditions, it signals the AFM system to activate.
- Hydraulic Valve Lifters: AFM-equipped engines use special hydraulic valve lifters that can collapse to prevent the intake and exhaust valves of specific cylinders from opening. This effectively deactivates those cylinders.
- Fuel Injection Control: The ECM also stops fuel injection to the deactivated cylinders, ensuring no fuel is wasted.
- Seamless Transition: When more power is needed, such as during acceleration or towing, the ECM reactivates the deactivated cylinders by restoring normal valve operation and fuel injection. This transition happens in milliseconds, making it imperceptible to the driver.
Benefits of Active Fuel Management
AFM offers several advantages for drivers and the environment:
- Improved Fuel Efficiency: By deactivating cylinders during light-load conditions, AFM reduces fuel consumption, helping drivers save money at the pump.
- Lower Emissions: With fewer cylinders firing, the engine produces less carbon dioxide, contributing to reduced greenhouse gas emissions.
- Maintained Performance: AFM ensures that full engine power is available when needed, providing the best of both worlds—efficiency and performance.
Maintenance Tips for AFM-Equipped Vehicles
To keep your AFM system functioning optimally, follow these maintenance tips:
- Regular Oil Changes: AFM systems rely on clean engine oil for proper operation. Stick to the manufacturer’s recommended oil change intervals and use the specified oil type.
- Monitor Engine Performance: If you notice unusual engine behavior, such as rough idling or decreased performance, have your vehicle inspected by a professional mechanic.
- Consider AFM Disabling Options: Some drivers choose to disable AFM using aftermarket tuners to avoid potential long-term wear on the system. Consult with an expert before making this decision.
Conclusion
GM’s Active Fuel Management is a smart technology that balances fuel efficiency and performance by deactivating engine cylinders when full power isn’t required. While it offers significant benefits, proper maintenance is essential to ensure the system operates smoothly over the life of the vehicle. If you have questions about AFM or need assistance with your GM vehicle, don’t hesitate to contact Kevin’s Autos for expert advice and service!
Frequently Asked Questions
Does AFM actually save fuel?
The fuel mileage is rarely affected allowing you to continue the same MPG you had before we deactivated the AFM to save thousands of dollars on repairs! Not to mention the hassle of being broke down on the side of the road or in a strange city on vacation.
What happens if you disable AFM?
When you eliminate the AFM system, the extra oil isn't needed. Excess oil will be pushed out of the pressure relief valve in the oil pan. This will spray oil on the bottom of the cylinder walls. This can cause oil burning, especially in high-rpm engines.
Why delete AFM?
Engines with AFM use a High-Volume Oil Pump. When you eliminate the AFM system, the extra oil isn't needed. Excess oil will be pushed out of the pressure relief valve in the oil pan.
Can you turn off GM Active Fuel Management?
The Range AFM/DFM Disabler allows your V6 or V8 GM vehicle to run in full cylinder mode at all times, preventing the Active and Dynamic Fuel Management systems from dropping cylinders.
Can you turn off AFM with a scan tool?
For some drivers, these changes in engine performance are distracting or unwanted, which leads them to disable AFM altogether. While there are many ways to disable the system, using a scan tool is one of the most direct methods, and it can often be done without needing any extra devices or hardware.
Does AFM ruin engines?
It can. The lifters can shred from hitting the cam lobe, and the metal from the lifters can get into your engine. If you catch it soon enough, it'll only be chips. If you let it go, you'll have pieces of lifters and camshaft bouncing around your engine block.
What happens if you delete AFM?
When you eliminate the AFM system, the extra oil isn't needed. Excess oil will be pushed out of the pressure relief valve in the oil pan. This will spray oil on the bottom of the cylinder walls. This can cause oil burning, especially in high-rpm engines.
How does the GM Active Fuel Management work?
When you're driving at cruising speeds or in conditions where your engine is not utilizing all power, the Active Fuel Management comes into play. This system detects when your engine does not need full power and will stop fuel delivery to half the cylinders, 3 on a V6 engine and 4 on a V8 engine.
What year to avoid AFM?
The AFM system is supposed to disable engine cylinders when you're not using them to help you save gas. Unfortunately, it was faulty, especially in the years between 2010 and 2014, which are definitely some of the Chevy Silverado model years to avoid.
Why do AFM lifters collapse?
Collapsed or stuck AFM lifters due to oil contamination will result in the same. Contamination/sludge is a major concern, prompting some to re-evaluate mileage service intervals. GM's Active Fuel Management (AFM) system allows a V8 engine to turn off half of its cylinders for fuel economy purposes.
