I recently started to experience a little low humming rattle sound in my truck engine when the AFM went from 4 cylinder to 8 cylinder. My truck has been service at the dealership since i bought it in December of 2011. Currently i have 128,00 miles on it. It is my daily driver to work (40 mile round trip) and whatever else i need around town. I have never pulled a trailer with it although it is equipped with the towing package. The truck is WELL maintained and never abused. The only aftermarket equipment i have on it is the nerf bars, front hood protector and rubber truck bed mat. I do not have an extended warranty on the truck even though they call me every month to tell me my warranty is about to expire? I check my gas mileage most of the time when i fill up. I get around 15-16 mpg.
So reading the other posts about the AFM being a problem, i started driving in M5. this eliminated the low humming rattle because it disabled the AFM. But i noticed my gas mileage went down to 13.5 mpg -14 mpg and i do not have over drive. So going up hill the truck would require a little more RPM to make it . And my truck was idling a little rough also. Still this was not a bad deal considering my truck is in good shape just less gas mileage and idling a little rough. I recently bought a Diablo Sport Tuner i3 on line. This would allow me to disable the AFM and get my over drive back on my truck. Upon receiving my Diablo Sport tune I updated it to the latest update. I then plugged it into my truck and began installing the "87 Octane" " Easy tune". In order for you to disable the AFM you have to go to the "Advanced Tune: tab and select "AFM/DOD" tab and it will ask you if you want have it " On/Off". Pretty simple device and self explanatory. I am by no means a rocket scientist but its pretty straight forward. Plus there are youtube videos that explain how to do it.
I filled my truck up with 87 octane fuel and am currently about 1/2 now. My truck is no longer idliing rough and i have my over drive back. So far so good on the tune and im looking forward to see how my gas mileage improves. On a side note GM has to acknowledge that this is a problem and offer a solution. Plus give an incentive on new trucks to previous owners. I have owned Chevy and GMC vehicles since 1987. Recently I bought my daughter a Nissan Rouge to protest GM. However im now in the market for a New Truck and looking at other Non GM products. Its sad that loyal customers have to settle for other products because the bottom dollar is what GM cares about. However this is Free Enterprise America and I want American made products. Just cant rely on GM anymore. Stay tuned for futher updates on the Diablo Sport tune

 

Never been a fan of cylinder cut-off. If you wanted a bit better mileage, which is in a heavy vehicle like a pickup truck, the 4.3
liter would get you 1.5-2.0 extra MPG and still had lots of torque. Cadillac tried it in the late 1970s and cylinder cut-off didn't last long. Neither did the 5.7/ 350 when GM tried to turn it into a diesel motor in 1979-1980. Get a six-cylinder or a small V8 instead.

Current small engines in the new 2022 model Chevy 1500 pickups:

• Duramax® 3.0L Turbo-Diesel Engine with 277 Horsepower and 460 Lb-Ft of Torque
• 2.7L Turbo Engine with 310 Horsepower and 348 Lb-Ft of Torque
• 4.3L EcoTec3 V6 Engine with 285 Horsepower and 305 Lb-Ft of Torque

No one here is going to care nor respond to you about a non-Chevy vehicle, so hit the road, Jack, and don't come back!

 

Thanks for your input