2014 - 2021 Corvette: Service Bulletin: #20-NA-038: Information on Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) Usage - (Apr 8, 2021)
Estimated Reading Time: 5 Minutes#20-NA-038: Information on Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) Usage - (Apr 8, 2021)
| Subject: | Information on Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) Usage |
This bulletin replaces PIP5663. Please discard PIP5663.
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Brand: |
Model: |
Model Year: |
VIN: |
Engine: |
Transmission: | ||
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from |
to |
from |
to | ||||
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Cadillac |
CTS |
2016 |
2019 |
— |
— |
6.2L (LT4) |
— |
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CT6 |
2016 |
2020 |
6.2L (LTA) |
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Escalade |
2015 |
2021 |
5.3L (L83) 6.2L (L86) |
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Chevrolet |
3500/4500 Medium Duty (LCF) |
2020 |
2020 |
6.6L (L8T) |
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Camaro |
2016 |
2021 |
6.2L (LT1, LT4) |
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Corvette |
2014 |
2019 |
6.2L (LT1, LT4, LT5) |
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2020 |
2021 |
6.2L (LT2) |
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Express |
2018 |
2021 |
4.3L (LV1), 6.6L (L8T) |
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Silverado |
2014 |
2018 |
4.3L (LV1, LV3) 5.3L (L83) 6.2L (L86) |
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Silverado 1500 (New Model) |
2019 |
2019 |
4.3L (LV3) 5.3L (L82, L84) 6.2L (L87) |
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Silverado LD |
2019 |
2019 |
5.3L (L83) |
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Silverado 1500 |
2020 |
2021 |
4.3L (LV3) 5.3L (L82, L84) 6.2L (L87) |
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Silverado 2500/3500 |
2020 |
2021 |
6.6L (L8T) |
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Suburban |
2015 |
2021 |
5.3L (L83, L84) 6.2L (L86, L87) |
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Tahoe |
2015 |
2021 |
5.3L (L83, L84) 6.2L (L86, L87) |
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GMC |
Savana |
2018 |
2021 |
4.3L (LV1), 6.6L (L8T) |
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Sierra |
2014 |
2018 |
4.3L (LV1, LV3) 5.3L (L83) 6.2L (L86) |
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Sierra 1500 (New Model) |
2019 |
2019 |
4.3L (LV3) 5.3L (L82, L84) 6.2L (L87) |
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Sierra Limited |
2019 |
2019 |
4.3L (LV3) 5.3L (L83) 6.2L (L86) |
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Sierra 1500 |
2020 |
2021 |
4.3L (LV3) 5.3L (L82, L84) 6.2L (L87) |
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Sierra 2500/3500 |
2020 |
2021 |
6.6L (L8T) |
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Yukon Models |
2015 |
2021 |
5.3L (L83, L84) 6.2L (L86, L87) |
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Involved Region or Country |
North America, Europe, Uzbekistan, Russia, Middle East, Iraq, Israel, Palestine, Argentina, Brazil, Bolivia, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay, Venezuela, Japan, Cadillac Korea (South Korea), GM Korea Company, China, Taiwan, Thailand, Singapore, Philippines, Egypt, Other Africa, South Africa |
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Information |
AFM (Active Fuel Management)
To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the cylinder deactivation system ON to deactivate engine cylinders 1, 7, 6, and 4, switching to a V4 mode. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications. AFM – active fuel management strategy which deactivates the lifters on specific cylinders. On V8 engines, it deactivates half of the cylinders (1,7,6 and 4) and on V6 engines, it deactivates only 2 of the cylinders (3 and 6). For LTA and LT2 engines, the deactivation occurs on cylinders 2, 3, 5 and 8. LOMA – lifter oil manifold assembly is only used on legacy AFM applications DFM (Dynamic Fuel Management) Dynamic Fuel Management (DFM) is recognized as active fuel management technology with the additional ability to deactivate any combination of cylinder valves for an internal combustion engine. This technology combines millisecond-accurate torque control with cylinder deactivation to optimize fuel consumption of spark ignited engines. The control of every cylinder event optimizes engine operation such that peak efficiency is obtained throughout the range of engine operation. DFM extends cylinder deactivation to all cylinders, which allows for a large variety of firing sequences. DFM can have rotating cylinder deactivation patterns as well as fixed patterns. For rotating patterns, which cylinders are 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 vehicle operator. DFM – dynamic fuel management which can deactivate the lifter on any cylinder at any time. Unlike AFM, this can result any many different types of firing patterns, some of which are fixed patterns (like ¼, ½, ¾) and others which are rotating (like 1/5, 1/3, 2/5, 2/3). This is only available on small block engines (L84 and L87). OCV – oil controlled valve is only used on small block engines. These provide faster response times than LOMA and are required for DFM (on L84 and L87). OCVs are also used on L82 for AFM. Refer to the AFM/DFM Usage Chart below. |
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AFM/DFM Usage Chart
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Vehicles
AFM VLOM
4 Cylinder Deactivation
DFM. OCV’s
FDFM
None
Notes
CTS LT4
Yes
Yes
No
No
—
Always active
CT6 LTA
No
Yes
No
No
—
—
Camaro LT1
Yes
Yes
No
No
—
Automatic only. AFM not active with Manual trans
Camaro LT4
Yes
No
No
No
—
Has the hardware, Not active
Corvette LT1
Yes
Yes
No
No
—
Auto Trans active, Manual Trans active in ECO only
Corvette LT2
No
Yes
No
No
—
—
Corvette LT4
Yes
Yes
No
No
—
Auto Trans active, Manual Trans active in ECO only
Corvette LT5
No
No
No
No
Yes
No hardware on LT5
Escalade L83, L86
Yes
Yes
No
No
—
—
Escalade L87
No
No
Yes
Yes
—
—
Express/Savana LV1
No
No
No
No
—
No hardware on LV1
Silverado/Sierra L83, L86
Yes
Yes
No
No
—
—
Suburban/Tahoe/Yukon L83, L86
Yes
Yes
No
No
—
—
Suburban/Tahoe/Yukon L84, L87
No
No
Yes
Yes
—
—
Silverado/Sierra L82
No
Yes
Yes
No
—
—
Silverado/Sierra L84
No
No
Yes
Yes
—
—
Silverado/Sierra L87
No
No
Yes
Yes
—
—
Silverado/Sierra L82, L84 with RPO YK9 Only
Yes
No
Yes
No
—
Hardware is there ECM and Software not capable
Silverado/Sierra HD L8T
No
No
No
No
—
No hardware on L8T
Silverado/Sierra LV1
No
No
No
No
—
—
Silverado/Sierra LV3
Yes
Yes
No
No
—
—
3500/4500 Medium Duty (LCF)
No
No
No
No
—
No hardware on L8T
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Information
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Note: Beginning in March 2021, most 2021 Silverado 1500 and 2021 Sierra 1500 pickups equipped with L82 MYC 6-speed and L84 MQE 8-Speed will be produced without Active Fuel Management/AFM (L82), or Dynamic Fuel Management/DFM (L84). The engines will still be equipped with the hardware, but the ECM and software will not be capable of activating this technology.
Pickups equipped with L82 MYC or L84 MQE, which are produced without AFM or DFM function, will be identified with New RPO YK9 (Not Equipped with Cylinder Deactivation).Internal components related to AFM or DFM function will be present in engines; wiring, connectors, and fuses will be present in vehicles with RPO YK9. The ECM will not be capable of activating the cylinder deactivation technology.
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Parts Information
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No parts are required for this repair.
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Version |
2 |
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Modified |
Released February 26, 2020 April 08, 2021 – Added 2021 Model Year to certain models, added additional vehicles to AFM/DFM Usage Chart and added the Information section. |