Can you turn off Chevy Active Fuel Management?
Yes, it’s possible to disable Active Fuel Management on many Chevrolet engines, but it isn’t officially supported by Chevrolet and comes with warranty, emissions, and legal considerations. The article below explains what AFM does, how owners generally disable it, and the risks and alternatives to consider.
What Active Fuel Management does
Active Fuel Management (AFM) is GM's cylinder deactivation technology that lets the engine run on fewer cylinders at light loads to save fuel. In many V8s, four cylinders are deactivated during steady highway cruising while the PCM reactivates them when the pedal demands more power or when certain systems require more torque. By reducing the number of active cylinders, AFM aims to improve fuel economy, though the trade-off can be subtle in some driving conditions and may introduce lifter noise or changes in engine feel for some drivers.
Can AFM be turned off?
Yes, disabling AFM is possible on many Chevrolet vehicles, but it's not an official, consumer-facing feature. The typical path is to have the PCM reprogrammed by a Chevrolet dealer or a reputable tuner to disable cylinder deactivation. Some owners opt for aftermarket tuning devices that claim to disable AFM. Each approach has benefits and risks, including warranty implications and potential emissions compliance concerns.
Common methods used to disable AFM
There are several routes owners pursue, from factory-supported reprogramming to third-party tuning. The most common options are listed below; each comes with considerations you should review with a professional.
- Dealer reflash or programming to disable AFM in the PCM (may require a service visit and is subject to regional rules).
- Authorized aftermarket tuners or programmers that modify PCM tables to permanently disable cylinder deactivation.
- AFM disable modules or software that claim to bypass AFM control (availability and legality vary by model and region).
- Physical modifications (such as lifter or valve changes) or exhaust alterations to defeat AFM—these are not recommended and can violate emissions laws and warranties.
Concluding note: If you’re considering disabling AFM, work with a licensed dealer or a reputable tuner who understands your local emissions laws and your warranty terms. An improper setup can trigger faults or drivability issues.
Key considerations before disabling AFM
Before making any changes, weigh the potential impact on warranty coverage, emissions compliance, and long-term engine health. The decision can affect your vehicle’s resale value and may require ongoing maintenance considerations.
- Warranty impact: disabling AFM can affect powertrain warranty eligibility.
- Emissions and inspections: many regions require intact emissions controls; tampering can cause a failed inspection or legal penalties.
- Drivability and reliability: improper calibration can cause vibration, misfires, or unexpected engine behavior under certain conditions.
- Documentation and legality: keep records of changes and confirm compliance with local regulations.
Concluding: If you decide to proceed, consult a qualified technician or dealer who understands both the vehicle’s software and local regulatory requirements.
What to expect after disabling AFM
Disabling AFM changes how the engine runs at light loads. While some drivers report a more consistent V8 feel, others see little to no improvement in fuel economy, and the change can affect engine behavior under certain conditions. Always monitor for warning lights and verify that the vehicle remains within legal emission standards.
- Engine operates on all cylinders under a wider range of conditions.
- Potential changes to fuel economy, typically less improvement in highway cruising than AFM achieved.
- Risk of check engine lights or drivability alerts if the calibration isn’t perfectly tuned.
- Warranty and emissions status may be affected.
Concluding: Disabling AFM is a trade-off between engine behavior and regulatory compliance. Pros and cons vary by model and driving style, so professional advice is essential.
Summary
Chevrolet’s AFM is designed to improve efficiency by deactivating some cylinders at light load. It can be disabled on many vehicles through dealer programming or reputable tuning, but doing so carries warranty, legal, and emissions implications. If you’re considering it, consult with a qualified technician, understand your local laws, and weigh whether the expected gains align with your vehicle's long-term health and resale value.
Can you disable cylinder deactivation?
Yes, you can disable cylinder deactivation using an electronic "disabler" device that plugs into the OBD-II port, a custom tune to the vehicle's computer, or by manually putting the transmission in a lower gear or a sport/tow/haul mode. For those who want a permanent, physical removal, a more complex "delete kit" can replace the system's components.
Methods to disable cylinder deactivation
This video demonstrates how to disable cylinder deactivation using a disabler device: 59s8020 AutomotiveYouTube · May 12, 2024
- AFM/DFM disabler: This is a simple and popular method. The device plugs into the OBD-II port and prevents the engine control unit (ECU) from shutting off cylinders.
- Custom tuning/remapping: A professional tuner can reprogram the vehicle's engine control module (ECM) to disable the system. This can also be used to tune for performance benefits like increased throttle response.
- Manual transmission mode: Shifting the transmission into a manual or "M" mode, or selecting a sport or tow/haul mode, will often keep the engine in its full cylinder configuration. This is often a simple, temporary solution.
- AFM/DFM delete kit: This is the most intensive option and involves physically replacing the AFM-specific components with standard parts. It's recommended if a component has already failed.
- Note: This method requires replacing the camshaft with a non-AFM version and making other adjustments, such as plugging the oil pressure relief valve, to prevent engine codes.
Can Active Fuel Management be turned off?
Yes, active fuel management (AFM) can be turned off by using a plug-in electronic disabler device or by installing a full delete kit with a software tune. Disablers are plug-and-play and prevent the system from activating, while delete kits replace the mechanical hardware and require reprogramming the engine's computer.
Methods for turning off AFM
This video explains why and how to disable GM's Active Fuel Management (AFM) system: 52sSummit RacingYouTube · Apr 28, 2021
- AFM Disabler:
- This is a plug-in device that connects to the OBD-II port and sends a signal to keep the engine in its full cylinder mode.
- It is a simpler and less expensive option that can be installed and uninstalled easily without leaving a trace.
- This method prevents the engine from ever entering the fuel-saving mode, but the internal AFM hardware remains in the engine.
- AFM Delete Kit:
- This is a more extensive and expensive option that involves physically replacing the AFM-specific hardware in the engine with standard components.
- It requires a professional software tune to disable the AFM function in the engine's computer, as the hardware is no longer there to activate it.
- This is the recommended method if AFM lifter failure has already occurred.
Is AFM bad for my engine's longevity?
However, AFM lifters have a history of failing. Oil consumption has also been a problem. This is bad for performance. When upgrading the engine, we recommend you Disable or Delete the AFM System.
Can I disable AFM without a device?
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.
