Range AFM disabler review - does it really keep the truck in V8 mode?

We haven't tested specific brands. How plug-in AFM disablers work in general:

• They plug into the OBD-II port and keep the computer from entering four-cylinder mode. No reflash, and the factory programming is unchanged.
• They're fully reversible — unplug it and AFM works normally again, which is why people use them on trucks still under warranty.
• They're a preventive measure. They don't fix a lifter that has already failed. If you already have a tick or a misfire, a disabler won't cure it.
• The AFM lifters and oil hardware are still in the engine. A tune that turns AFM off does the same job permanently; a full delete removes the hardware.

See what AFM is and whether to delete it.