2014 - 2021 Corvette: Service Bulletin: #20-NA-038: Information on Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) Usage - (Apr 8, 2021)

#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.


Brand:

Model:

Model Year:

VIN:

Engine:

Transmission:

from

to

from

to

Cadillac

CTS

2016

2019

6.2L (LT4)

CT6

2016

2020

6.2L (LTA)

Escalade

2015

2021

5.3L (L83)

6.2L (L86)

Chevrolet

3500/4500 Medium Duty (LCF)

2020

2020

6.6L (L8T)

Camaro

2016

2021

6.2L (LT1, LT4)

Corvette

2014

2019

6.2L (LT1, LT4, LT5)

2020

2021

6.2L (LT2)

Express

2018

2021

4.3L (LV1), 6.6L (L8T)

Silverado

2014

2018

4.3L (LV1, LV3)

5.3L (L83)

6.2L (L86)

Silverado 1500 (New Model)

2019

2019

4.3L (LV3)

5.3L (L82, L84)

6.2L (L87)

Silverado LD

2019

2019

5.3L (L83)

Silverado 1500

2020

2021

4.3L (LV3)

5.3L (L82, L84)

6.2L (L87)

Silverado 2500/3500

2020

2021

6.6L (L8T)

Suburban

2015

2021

5.3L (L83, L84)

6.2L (L86, L87)

Tahoe

2015

2021

5.3L (L83, L84)

6.2L (L86, L87)

GMC

Savana

2018

2021

4.3L (LV1), 6.6L (L8T)

Sierra

2014

2018

4.3L (LV1, LV3)

5.3L (L83)

6.2L (L86)

Sierra 1500 (New Model)

2019

2019

4.3L (LV3)

5.3L (L82, L84)

6.2L (L87)

Sierra Limited

2019

2019

4.3L (LV3)

5.3L (L83)

6.2L (L86)

Sierra 1500

2020

2021

4.3L (LV3)

5.3L (L82, L84)

6.2L (L87)

Sierra 2500/3500

2020

2021

6.6L (L8T)

Yukon Models

2015

2021

5.3L (L83, L84)

6.2L (L86, L87)

 

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

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.

AFM/DFM Usage Chart 

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

Information

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.

Parts Information

No parts are required for this repair.

Version

2

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.

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