The AFM (Active Fuel Management) system on the GMT900 5.3L is responsible for a huge number of lifter failures. Deleting it without a tune is possible using a plug-in device, and it’s one of the most popular mods on the 2007–2013 Silverado/Sierra platform.
Why Delete AFM?
- Prevents the constant cycling of AFM lifters, which is the primary cause of early lifter failure
- Smoother throttle response
- The factory AFM system can cause excessive oil consumption
Option 1: Range Technology AFM Disabler (No Tune Required)
The easiest and most popular solution. Plugs into the OBD2 port and commands the ECU to run all 8 cylinders at all times. No permanent modification, no tune needed, and fully reversible.
Range Technology RA003B AFM/DFM Disabler – Plug-and-play, works on all 2007–2013 5.3L and 6.0L GM trucks and SUVs.
How It Works:
- Plug into OBD2 port under the dash
- Blue LED indicates active
- The ECU keeps all 8 cylinders firing at all times
- No CEL, no codes, fully reversible by unplugging
Option 2: AFM Delete with a Tune
Using HPTuners or EFI Live, a tuner can completely disable AFM in the ECU calibration. This is the permanent solution and also the best if you’re already getting a tune for performance.
What About DFM (Dynamic Fuel Management)?
On 2019+ trucks, GM upgraded to DFM (Dynamic Fuel Management) which uses even more cylinder deactivation patterns. The Range Technology device works on DFM-equipped trucks as well – look for the RA003B model.
Fuel Economy Impact:
Expect to lose 1–2 MPG on the highway by disabling AFM, but most owners consider the peace of mind well worth it.
Has anyone deleted AFM on their GMT900? What method did you use? Drop your experience below.