Are you a Pontiac G8 Gt owner noticing a peculiar engine behavior, especially at highway speeds or around 1800-2000 RPM? You might be experiencing Active Fuel Management (AFM), a system designed to improve fuel economy. Let’s delve into what AFM is and what it means for your G8 GT.
What is Active Fuel Management (AFM) in the Pontiac G8 GT?
Active Fuel Management, also known as cylinder deactivation, is a technology implemented by General Motors in vehicles like the Pontiac G8 GT equipped with the L76 engine. Contrary to some initial assumptions, the 2008 Pontiac G8 GT does indeed feature AFM. This system is engineered to enhance fuel efficiency by seamlessly shutting down four of the eight cylinders under light load conditions, such as cruising on the highway.
When AFM is active, your G8 GT effectively operates as a four-cylinder engine, reducing fuel consumption. The transition between eight-cylinder and four-cylinder mode is intended to be smooth and unnoticeable. However, some drivers, especially those with aftermarket exhaust systems like axle-backs, may perceive a drone or change in exhaust note when AFM engages.
What Happens When AFM is Disabled on a Pontiac G8 GT?
Disabling AFM means your Pontiac G8 GT will consistently run on all eight cylinders. While this might slightly reduce fuel economy – as noted by forum users experiencing a 2-3 MPG decrease – it can eliminate the drone associated with AFM engagement.
There are several ways to disable AFM on your Pontiac G8 GT:
- Using a Tuner: Devices like the Cortex mentioned in the forum can be used to turn off AFM through ECU programming.
- Engineering Mode: As suggested in the forum, you can check AFM status and potentially disable it via the car’s engineering mode, accessible through the steering wheel controls.
- Manual Mode: Simply shifting your G8 GT into manual mode is a quick way to disengage AFM, ensuring all eight cylinders are active.
For Pontiac G8 GT enthusiasts prioritizing a consistent V8 exhaust note and performance feel over marginal fuel savings, disabling AFM can be a worthwhile modification. Experimenting with these methods will help you determine if turning off AFM resolves unwanted drone and aligns with your driving preferences.
Ultimately, understanding AFM in your Pontiac G8 GT empowers you to make informed decisions about its operation, whether you choose to keep it active for fuel efficiency or disable it for a more consistent driving experience.
