What's the difference between AFM and DFM?

Author: Josh Greenwald | 04/28/2020 < Back to Blog Home
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Starting in 2019, GM made the switch on some 5.3L and 6.2L V8 engines from their Active Fuel Management system to their new Dynamic Fuel Management system. Like the old AFM system, DFM can temporary deactivate and reactivate cylinders to try to help improve fuel economy. While the AFM system would simply transition to 4 cylinders from 6 or 8 depending on the motor, the new DFM system uses up to 17 different patterns to deactivate cylinders.


In both systems, the two-piece valve lifters collapse on themselves upon deactivation, preventing the valve to open. The problem is over time, these lifters wear at an accelerated rate from the constant activation cycles from the Fuel Management system, ultimately causing them to fail and require an expensive replacement. Other issues caused by the AFM/DFM systems is unpleasant drone sounds from the engine running on reduced power, and shuddering or even rough shifting of the transmission from the increased demand caused by the slower-performing engine.


As a result, these systems actually can cause a decrease in fuel economy. Our module works to ensure that these lifters always stay engaged, keeping your engine running on all cylinders, all the time.

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