High fuel prices have seen consumers searching for alternatives to curb fuel usage. Some are changing to diesel, others hybrids, while others are opting for smaller and lighter vehicles with a mission of saving on fuel.
With the unpredictable fuel prices, automotive manufacturers have come up with a technology whose aim is to improve fuel mileage known as Active Fuel Management.
Read through to know how to tell if a vehicle has active fuel management and much more related information.
What is Active Fuel Management?
Active Fuel Management is simply an automotive engine technology from General Motors that deactivates parts of engine cylinders when driving under light conditions thus reducing fuel consumption rate.
Mostly, AFM technology is meant for large GM vehicles with V6 or V8 engines. V6 engines are temporarily turned into inline V3 engines while V8 engines are reduced to V4 engines.
According to a concept behind AFM technology, high-powered engines such as V6 and V8 are excessively inefficient when high-demand power is not necessary.
Therefore, instead of installing a smaller engine to improve engine efficiency which might as well compromise acceleration and towing capacity, AFM technology switches off unnecessary cylinders effectively as required.
At the beginning of the deactivation process, exhaust and intake valves are turned off. Pressurized oil signals solenoids to enable and disable the lifters.
These lifters are the mechanism that physically open and close intake valves and the exhaust. Once the valves are deactivated, exhaust gas remaining in the cylinders fills out in one cylinder as it delates in another.
Power is adequately maintained in situations where demand is low through this compression.
In situations where more power is required, the exhaust valve is deactivated to transfer the older exhaust gas and a new cycle begins. During this process, cylinders 1, 4, 6, and 7 shut on V8 engines.
How to Tell If Your Vehicle Has Active Fuel Management?
If your vehicle is using a V6 or V8 engine, it’s likely to have active fuel management technology.
You will notice when the mode switches from 8cyl to 4cyl if you are using a V8 engine or from 6cyl to 3cyl if you are using a V6 engine.
With an active fuel management indicator, it will reflect on the Driver Information Center (DIC). Below is a table showing current General Motors Engines with this application:
|First-generation High Feature V8 DOHC engine family||· 4.2 LTA Twin-Turbo|
|First-generation GM EcoTec3 engine family||· 4.3L V6 LV3
· 5.3L V8 L83
· 6.2L V8 L86
|Second Generation GM High Feature V6 DOHC engine family||· 3.6 L V6 LGX Naturally Aspirated
· 3.0L V-6 LGW Twin-Turbo
|Fourth-generation GM Small Block engine family||· 5.3L V8 Vortec 5300
· 3.9L V6 LZ8
· 5.3L V8 LS4
· 6.2L V8 L99
You might like to read more about chevy 6.0L Vortec engine upgrage.
Features of an Engine Fitted with Active Fuel Management
- Valley Cover – Active Fuel Management cover is ribbed on top by solenoids on the bottom side and an electrical interface on the rear end. All engines without an AFM system consists of a smooth cover.
- Engine block – All fourth-generation engines have oil passages and AFM towers and cast in, but they only work with engines using the AFM system.
- Lifters – The fourth generation and early fifth generation V8 engines use unique lifters ON cylinders 7, 6, 4 and 1. They can be identified by the springs mounted on the top since they are tall. Engines with AFM also use a camshaft, high-volume oil pump, and a pressure relief valve in the oil pan.
- Oil pressure relief valve – The valve is found on the oil pan rail and it blocks excess oil pressure from erratically affecting AFM components. The initial 2007-2009 dispersed oil on the cylinder increasing oil usage. To fix this, GM put in a deflector part number 12639759 in 2010 to divert it into the oil pan. This can be put in your older model if you encounter high oil consumption.
What Vehicles Have Active Fuel Management?
Below is a table showing different brands from General Motors fitted with this technology application:
|Buick||· Buick LaCrosse with 3.6L V-6 LGX|
|GMC||· K2XX GMC Sierra 1500 with 4.3l V8 LV3
· K2XX GMC Sierra 1500 with 5.3l V8 L83
· K2XX GMC Sierra 1500 with 6.2L V8 L86
· K2XX GMC Yukon and Yukon XL with 5.3 V8 L83
· K2XX GMC Yukon Denali and Yukon XL Denali with 6.2L V8 L86
|Chevrolet||· K2XX Chevrolet Silverado 1500 with 4.3l V8 LV3
· K2XX Chevrolet Silverado 1500 with 5.3L V8 L83
· K2XX Chevrolet Silverado 1500 with 6.2L V8 L86
· K2XX Chevrolet Tahoe with 5.3L V8 L83
· K2XX Chevrolet Suburban with 5.3L V8 L83
|Cadillac||· Cadillac Escalade with 6.2L V8 L86
· Cadillac CT6 with 3.6L V6 LGX
· Cadillac CT6 with 3.0L Twin Turbo V6 LGW
· Cadillac CT6 with 4.2L Twin Turbo V8 LTA
· Cadillac CTS with 3.6L V6 LGX
· Cadillac ATS with 3.6L V6 LGX
· Cadillac XT5 with 3.6L V6 LGX
What Year Silverados Have AFM?
Since Active Fuel Management technology was introduced in 2007, all Silverado models released after that were outfitted with this technology.
However, the 2019 Chevy Silverado, which marked the launch of the completely overhauled fourth-generation for the light-duty pick-up on the GM T1 platform, had three engines equipped with AFM technology.
The other two engines had a similar technology known as Dynamic Fuel Management (DFM), a successor of Active fuel management.
In the 2022 Silverado engine lineup, Active Fuel Management technology has nearly been phased out since only one engine is equipped with Active Fuel Management.
The turbo-charged 2.7L I-4 L3B. Other engines namely, the 3.0L I-6-LM2 turbodiesel Duramax, the naturally-aspirated 5.3L V-8 L84 gasoline engine, and the naturally-aspirated 6.2L V-8 L87 gasoline engine do not have AFM.
Both L87 and L84 have Dynamic Fuel Management while the 3.0L I-6 LM2 features neither AFM nor DFM.
Having this information in your mind, it is evident that Active Fuel Management is slowly exiting from the Silverado engine lineup.
Instead, Dynamic Fuel Management is being incorporated in some engines while in some cases like an LM2 diesel engine, there is no fuel management system outfitted at all.
Note that, the ongoing global microchip shortage has also contributed to some 2021 and 2022 Silverado models being not outfitted with either of the fuel management systems.
GM Active Fuel Management Problems
Since all Active Fuel Management systems use oil control solenoids and pressurized engine oil, they require a sufficient supply of uncontaminated oil to function as desired.
However, most issues related to these systems originate from oil pressure control issues and oil supply. Below are some of the problems associated with Active Fuel Management:
01. Excessive Oil Consumption
Although the aim of installing Active Fuel Management was to reduce fuel economy, many drivers with GM vehicles outfitted with this technology have had a contrary experience.
Most of them still experience excessive oil consumption on their vehicles to be.
In response to this, GM released TS 10-06-01-008F stating that in case oil usage exceeds 750ml per 3200 to 4800km in normal driving circumstances, you should confirm whether:
- There is any oil passing through the positive crankcase ventilation (PCV) system to the intake system.
- There is mist or oil spray or mist being accumulated in the intake system via the AFM system’s pressure relief valve located in the PCV. There are more chances of this problem happening during prolonged high speed driving conditions. Mostly, oil mist accumulates in the piston ring grooves where it partly changes into carbon deposits, escalating oil usage even more. Spark plug failures and fouling are likely to occur due to overheating.
02. Lifter Failure
AFM lifters fail more often compared to non- AFM lifters leading to excessive oil consumption. Excess oil consumption can cause pressure to drop, low oil levels, and failure of some major components like the timing chain.
To avoid spending unnecessary maintenance costs on AFM-related repairs, the best option is simply to disable or delete the AFM system.
How to Delete or Disable Active Fuel Management System (step by step guideline)?
You can either disable the AFM system or delete it completely.
But before you make your final decision, it is important to note that the AFM system has some special parts that include lifters and the Lifter Oil Manifold Assembly (LOMA) or valley cover.
In addition, it also has a unique oil pressure relief valve, high-volume oil pump, and a different camshaft. Deleting the whole system means replacing all these parts which can be quite expensive.
While disabling the system simply means adjusting the engine ECU so that it never activates the AFM system.
Essentially, it prevents the valley cover solenoids from ever opening which ensures that your engine is always in V8 mode.
How to Disable AFM system?
Disabling the AFM system requires adjusting or reprogramming the ECU into staying in V8 mode. However, reprogramming can void the engine warranty for someone with a factory warranty. To avoid this, it is recommended that you use a Range Technology disabler as it is the only AFM disabler device that doesn’t reprogram your ECU.
- Simply plug the AFM disabler device directly into the OBDII port. It begins functioning immediately. You can easily remove the device anytime you want to reverse the process.
- You can as well use a standard oil pump instead of a high-volume oil pump. A high-volume oil pump passes excess oil which can cause oil build-up on the cylinder walls causing cylinder walls scoring or burning. Though it may take some time, it’s important to prevent future internal engine issues.
How to Delete AFM System?
Deleting the AFM system is recommended when it is the only option left since you will be required to replace all the AFM components. Circumstances under which you can have the AFM system deleted are when you have failed lifters.
Follow the following steps to delete the AFM system:
- Replace the Camshaft with another camshaft that is not fitted with the AFM.
- Switch the Active Fuel Management lifters with standard lifters.
- Substitute the valley cover with a flat valley cover that is not fitted with the AFM.
- Deactivate the Active Fuel Management system using the custom tune or the Range Technology Disabler.
- Connect the pressure relief valve to the oil pan.
- Switch the high-volume oil pump with a standard oil pump.
How to Disable AFM Without a Tune?
If you have a warranty and you don’t intend to render it void, you can disable your AFM system without a tune in the following ways:
- Using an AFM Disabler – An AFM disabler is easy to install, activate and uninstall. Once it is removed from the OBD II port, all the functions of the AFM system are restored.
- Removing the Brake Booster Vacuum Sensor – Removing the brake booster vacuum sensor is another way of deactivating the AFM system though it can be problematic, especially with the check engine light coming on.
Frequently Asked Questions (FAQs)
Do All 5.3 Engines Have AFM?
No. Since the introduction of the AFM system, GM produced all 5.3 engines outfitted with an AFM system until 2021-2022 when they began replacing it with Dynamic Fuel Management (DFM) or no fuel management system at all.
How to tell if Active Fuel Management is Working?
With an Active Fuel Management indicator, you will notice when the mode of your engine changes depending on circumstances.
For V8 engines, cylinders 1, 7, 6, and 4 are deactivated while on V8 engines. However, the engine will function on all cylinders during medium to heavy throttle applications, engine starting, and engine idling.
How do You Prevent AFM lifters from Failing?
Simply use high-quality oil on your vehicle, service your car regularly, and since the AFM system is the ultimate cause of lifter failure, you can use an AFM disabler to deactivate the AFM system.
Having known how to tell if a vehicle has active fuel management, the AFM technology also happens to be a major problem facing GM vehicles.
However, some drivers have a good experience with the same AFM system and this proves it to be a situation of hit or miss.
You can still have a vehicle with an AFM system and still not use them especially if they are not serving you right.