GM TechLink:
August 9, 2019
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 Cadillac 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
Article ID: 1418
Created: May 5, 2020
Last Updated: May 5, 2020
Online URL: https://www.corvetteactioncenter.com/tech/knowledgebase/article/2016-2019-corvette-gm-techlink-active-fuel-management-dynamic-fuel-management-on-gm-models-1418.html