Leave AFM Off or On? Really any difference in MPG?

[Tylus]

have you verified the speed via GPS

Yes. Corrected in the PCM for larger tires. Was 2 mph slow before tuning

And keep in mind Inhave a 2017 Direct injection motor. Slightly different from prior gen LS engines

 

[Windboy]

From my experience, AFM could save around 1~2 mpg on the highway (maybe slightly better in some conditions). The good thing about turning it off is it can make your engine more smooth. But since you're doing highway driving, AFM isn't that annoying and it would be probably better to turn it off.

 

[Windboy]

From my experience, AFM could save around 1~2 mpg on the highway (maybe slightly better in some conditions). The good thing about turning it off is it can make your engine more smooth. But since you're doing highway driving, AFM isn't that annoying and it would be probably better to turn it off.

 

[Tylus]

I’m seeing the best MPG I’ve ever seen since 2014 when I bought my 2015 Tahoe.

55 mph is netting me 24+ mpg. And my mixed driving is at 18.3 mpg right now. I’ll get the true hand calc numbers when I fill up soon. the digital meter is spot on usually. Unless I idle a ton with AC on

Before tuning I never saw these numbers. I love it. And the better driveability is pretty awesome.


As far as AFM, at true highway speeds it never comes on. So me getting 20-21 mpg is strictly V-8. Which is impressive for such a large rig.

The AFM activates 90% of the time under 60 mph. Which really reflects the huge bump in mpg. So for now I’m keeping it on.

 

[Windboy]

From my experience, AFM could save around 1~2 mpg on the highway (maybe slightly better in some conditions). The good thing about turning it off is it can make your engine more smooth. But since you're doing highway driving, AFM isn't that annoying and it would be probably better to turn it off.

 

[cardude2000]

Just gun it all the time and it seems like afm doesn’t come on as much. Sounds better and it’s more fun.

 

[Bob2C]

With AFM off using Range device I get between 23-25 mpg on highway going about 65. With it turned on the computer said best was 28 but typically gets 26 under same conditions. Personally I really don’t care about the fuel mileage. I would rather keep it off after hearing all the stories about lifters collapsing. Plus the truck is more responsive and shifts better.

 

[BigBlueLB756]

Premium bottled water costs more per gallon than premium Top Tier gasoline.

 

[Brad LeFevre]

Florida to TX road trip. AFE delete, BB tune for ECU and transmission, AFE CAI, Yukon DXL w/6.2. Averaged 75mph and 20.9. In fairness I did not mileage check when I filled up, however, this mileage is right in line with my results pre tune and stock air intake.