Experiencing mysterious vibrations in your truck? You’re not alone. Many truck owners, especially those with General Motors vehicles, have encountered frustrating vibration issues that dealerships often misdiagnose. One such story begins with a 2007 GMC truck plagued by vibrations at specific speeds – a shake so intense it felt like it would rattle everything loose. Despite thorough checks of the usual suspects like the rear end and driveshaft, and even a transmission inspection, the problem persisted. The real culprit, as it turned out, was the Active Fuel Management (AFM) system and its related injectors, a repair initially estimated at a hefty $4,000. Instead of pursuing that costly repair, the truck was traded in for a newer, gently used 2015 Silverado Crew.
This experience highlights a growing concern among automotive enthusiasts and even some experts: the GM AFM system. Designed to improve fuel economy by switching between 4 and 8 cylinders depending on driving conditions, AFM is increasingly being seen as a potential source of engine problems. The theory is that engines not originally engineered for constant cylinder deactivation can suffer from the stresses and imbalances created by this system. This was likely the root cause of the vibrations in the older GMC truck.
To prevent similar issues in the newer Silverado, a proactive measure was taken: installing a Range Technologies OBD2 AFM Disabler. This device plugs directly into the OBD2 port and effectively keeps the engine running in 8-cylinder mode at all times. The result? Not only were vibration concerns eliminated, but surprisingly, fuel mileage even improved. The Range Obd2 Afm Disabler appeared to be a win-win solution.
However, one minor inconvenience has emerged with the Range Technologies unit. If the truck sits unused for several days, the disabler seems to “go to sleep.” When this happens, the AFM system can reactivate, allowing the engine to switch back into V4 mode until the Range device is unplugged and plugged back in. This raises a question for other users of Range OBD2 AFM disablers: Has anyone else encountered this “sleeping” issue, and are there any known fixes or workarounds? For those seeking to eliminate AFM-related vibrations and potentially improve fuel economy, the Range OBD2 AFM disabler offers a promising solution, but understanding and addressing minor quirks like this “sleeping” issue is crucial.
