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

[Tylus]

Edge Evolution CS2 on Level 3
AFM turned off
Tire correction factor for my larger than factory tires


My around town MPG appears better and highway a tad worse. I'm about to drive 1600 miles round trip. Will turning AFM back on gain me anything WHILE keeping the tune? Looking for input from those who've driven long distances tuned with AFM ON vs. OFF.

 

[iamdub]

Edge Evolution CS2 on Level 3
AFM turned off
Tire correction factor for my larger than factory tires


My around town MPG appears better and highway a tad worse. I'm about to drive 1600 miles round trip. Will turning AFM back on gain me anything WHILE keeping the tune? Looking for input from those who've driven long distances tuned with AFM ON vs. OFF.

I've only had one long trip with AFM on and one with it off. Straight highway, I lost 2 MPG with it off. With my 195K-mile '08 with a lifter that ticks for a few seconds at startup, I keep it turned off. If your trip will be steady cruising on mostly flat land at speeds no more than 70-75, then you should benefit some from AFM.

 

[BigBlueLB756]

I just recently traveled from MS up to Indy area and back. 1521 miles. 22.1 mpg. Tuned w/ AFM off. Catch can working. Very satisfied with Tahoe performance. Caught this snot:

 

[Tylus]

Well just drove to Savannah today and back. About 300 miles round trip at 73mph

20 mpg with wicked headwinds and rain

AFM was on. But it never went into V-4 mode. Guess I’ll just turn AFM back off in the programming.



For reference my 2015 Tahoe averaged 23 mpg in 2016 when I drove across country from LA to NYC. 20+ mpg tuned is decent in my eyes

 

[swathdiver]

Well just drove to Savannah today and back. About 300 miles round trip at 73mph

20 mpg with wicked headwinds and rain

AFM was on. But it never went into V-4 mode. Guess I’ll just turn AFM back off in the programming.



For reference my 2015 Tahoe averaged 23 mpg in 2016 when I drove across country from LA to NYC. 20+ mpg tuned is decent in my eyes

Not bad, I've lost 2-3 mpg just driving on wet roads at highway speeds before!

 

[pt1965]

wow, i have the lc9 with afm, but the best i have done on extended trip is 18mpg! doesnt matter if i go 70 or 80. most of the time its 16-17 mpg.
whats the secret??

 

[Tylus]

wow, i have the lc9 with afm, but the best i have done on extended trip is 18mpg! doesnt matter if i go 70 or 80. most of the time its 16-17 mpg.
whats the secret??

Suburban
2.5” leveling kit
33” tires (e-rated)
Level 3 programming (street tune) with AFM on

CRUISE CONTROL!!!!

Lol. Drove 524 miles at 71 mph. Got 20.3 MPG hand calculated. Lie-o-meter said 20.9 mpg. That was 1 tank of gas for 524 miles

Drove another 180 miles at 62 mph and got 23.9 mpg.


The biggest influence is consistency. Put cruise control on and just cruise. Resist using right pedal

 

[BG1988]

have you verified the speed via GPS

try 59MPH? I get 25 to 28mpg..


36MPG-e-assisted seem pretty average in the city.. by manipulating the hybrid module and AFM .. and manipulating the acceleration ...


0 to 30 in EV mode (electric motors) then 30 to 41 on the ICE

41= 40-43MPG instant... =36-38MPG IRL



Then if I see a stop slight ahead i drop it to 29mph so it will switch back to EV mode...


this is basically the most fuel efficient possible way to drive the SUV....


basically the engine is just sitting there idling at 1050-1150rpm in v4 mode
using tiny amounts of gas..



I really Wish i could enter auto stop at higher speeds on downhill
other hybrids can do it but not this suv... this would save a ton of gas

 

[swathdiver]

wow, i have the lc9 with afm, but the best i have done on extended trip is 18mpg! doesnt matter if i go 70 or 80. most of the time its 16-17 mpg.
whats the secret??

PT, Jeremiah's secret is his Direct Injection motor, he's not driving a GMT900, he's got a K2!

 

[swathdiver]

I really Wish i could enter auto stop at higher speeds on downhill
other hybrids can do it but not this suv... this would save a ton of gas

HP Tuners or EFI Live!?

 

[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.