This is caused by VCM, the front bank works all the time.
VCM stands for Variable Cylinder Management. It is a technology that allows a V6 engine to run on 3, 4, or 6 cylinders depending on the load and driving conditions. This can improve fuel economy by up to 5%.
On J series engines, VCM is controlled by the Engine Control Unit (ECU). The ECU monitors the engine speed, throttle position, and other factors to determine when to deactivate cylinders. When the ECU determines that 3 cylinders can be deactivated, it will close the valves on those cylinders and stop the spark plugs from firing. This effectively turns the V6 engine into a 3-cylinder engine.
VCM is not active all the time. It only activates when the engine is under light load, such as when cruising at a steady speed. When the engine is under heavy load, such as when accelerating or climbing a hill, VCM will deactivate.
VCM has been criticized for causing problems with engine oil consumption and emissions. However, Honda has made improvements to the VCM system over the years, and the problems have been reduced.
Here are some of the benefits of VCM on J series engines:
Improved fuel economy: VCM can improve fuel economy by up to 5%.
Reduced emissions: VCM can help to reduce emissions by running the engine on fewer cylinders when they are not needed.
Smoother ride: VCM can help to provide a smoother ride by eliminating the vibrations that can occur when a V6 engine is running on only 3 cylinders.
Here are some of the drawbacks of VCM on J series engines:
Increased oil consumption: VCM can cause increased oil consumption, especially in older engines.
Increased emissions: VCM can slightly increase emissions, especially in older engines.
Problems with the VCM system: The VCM system can malfunction, which can cause problems with the engine, such as misfires and rough idle.