Active Fuel Management/Dynamic Fuel Management on GM Models

Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) is available on a number of recent GM models to help improve fuel economy, including 2014-2019 Corvette, Silverado LD, Sierra Limited; 2015-2019 Escalade, Suburban, Tahoe, Yukon; 2016-2019 CTS-V, Camaro; 2019 Silverado 1500, Sierra 1500; 2020 Silverado 2500/3500 and Sierra 2500/3500 models.

 

Active Fuel Management

AFM was designed to provide maximum fuel economy under light load driving conditions by deactivating the lifters on specific cylinders. On V8 engines, half of the cylinders are deactivated and on V6 engines, two of the cylinders are deactivated.

Under certain operating conditions, the Engine Control Module (ECM) commands the cylinder deactivation system to deactivate engine cylinders 1, 7, 6, and 4 on V8 engines or to deactivate engine cylinders 3 and 6 on a V6 engine. The engine will operate on all cylinders during engine starting, engine idling and medium-to-heavy throttle applications.

The Lifter Oil Manifold Assembly (LOMA) is only used on AFM applications.

 

Dynamic Fuel Management

DFM is the next generation in cylinder deactivation systems. It features AFM technology with the additional ability to deactivate any combination of cylinder valves to optimize fuel consumption. The control of every cylinder event allows peak efficiency to be obtained throughout the range of engine operation. (Fig. 15)

 

Fig. 15

 

By extending cylinder deactivation to all cylinders, DFM allows for a large variety of firing sequences. DFM can have rotating cylinder deactivation patterns, such as 1/5, 1/3, 2/5, or 2/3, as well as fixed patterns, such as 1/4, 1/2, or 3/4. For rotating patterns, which are only available on small block engine (L84,L87), the cylinders being deactivated can change with each subsequent engine cycle. Transitions between firing sequences is done in a continuous fashion, making the transitions seamless and transparent to the driver.

Oil Control Valves (OCV), only used on small block engines, replace the LOMA. OCVs provide faster response times than the LOMA and are required for DFM. OCVs also are used on L82 engines with AFM.

 

AFM/DFM Usage
Model AFM VLOM 4 Cylinder Deactivation DFM OCV FDFM None Notes
CTS-V 6.2L LT4 Yes Yes No No Always active
Camaro 6.2L LT1 Yes Yes No No Automatic only. AFM not active with manual trans
Camaro 6.2L LT4 Yes No No No Has the hardware, not active
Corvette 6.2L LT1, LT4 Yes Yes No No Auto trans active, manual trans active in ECO only
Corvette 6.2L LT5 No No No No Yes No hardware on LT5
Escalade 6.2L L86 Yes Yes No No
Suburban/Tahoe/
Yukon 5.3L L83, 6.2L L86
Yes Yes No No
Silverado LD/Sierra LD 5.3L L83, 6.2L L86 Yes Yes No No
Silverado/Sierra 4.3L LV3 Yes Yes No No
Silverado 1500/Sierra 1500 5.3L L82 No Yes Yes No
Silverado 1500/Sierra 1500 5.3L L84, 6.2L L87 No No Yes Yes
Silverado/Sierra HD 6.6L L8T No No No No No hardware on L8T
Express/Savana 4.3L LV1 No No No No No hardware on LV1
Express/Savana 6.6L L8T No No No No No hardware on L8T

 

 

For additional information, refer to #PIP5663.

 

– Thanks to Richard Renshaw

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