Who has disabled AFM and what did it do to your MPG?

[eagle-co94]

I'm curious because I'm still bounding back and forth between the LS3 and L99 idea. I know I can buy a Range (http://www.rangetechnology.com/" onclick="window.open(this.href);return false;) to use when on road trips or commuting or just have AFM removed in tuning but I'm curious if anyone has seen any noticeable losses from removing it.

[Pursuit]

I have diabled it in tuning and drove the car from Omaha, NE to Ames, IA. 3.45 rear gear. Speed limit is 70 mph, cruise set at 72. 19-20 mpg w/o AFM. 22-23 with AFM active. I have done that a few times, just to see the difference. 72 mph is at the top range of the AFM activating. Any faster and I am outside of the RPM, throttle position % parameters.

Maurice

[GTObert]

I disabled it and if there was a difference I couldn't tell. I just looked at that Range thing; I had never heard of it before. For my money, I'd rather use a couple more gallons of gas now and prevent engine problems later. Engines are expensive and gas is cheap these days.

[eagle-co94]

I'm leaning towards getting an LS3 to replace my locked up L77 instead of an L99 since both motors are plentiful from wrecked Camaros. I found out about the Range from the Camaro community.

[leadfart]

I disabled DOD, when I put the blower on. I actually get an 20 or so, if I stay under 70. That's very close to what I would average with the NA engine, unless you really babied it, on smooth road. AFM doesn't help very much, on this engine.IMO

[The Tech]

I had the AFM disabled when I had the tune done. I saw a two mpg gain along with 80 more rwhp - although that was due more to switching to Premium from Regular than turning off the AFM. The way I drive my car I doubt the AFM was able to help me much.

[bsparks72]

I just typed a long response, only to have the forum blip out and erase it when I hit submit. That said, my Saab had it prior to a tune, and I noticed no loss of mpg. I think with a good tune, you won't either. The AFM is so picky that I can go one way down a road and it will work, and on the return trip at the same speed it will not due to a headwind. If you go too slow, it won't work. If you go to fast, it won't work. It would take a flat road at the perfect speed for a long distance to make any difference. And then you're risking increased oil consumption. Kill it and don't look back.

[eagle-co94]

This is interesting to hear because I had a 2012 Dodge Charger Pursuit with the 5.7 Hemi and I could pull mid to high 20s on the highway because it would stay in 4cyl mode until you went about 1/2 throttle.

[bsparks72]

I know with the 2.92 gear and the .667 overdrive, the sweet spot seems to be about 80 mph. That's just over 2000 rpms.

[CrashTestDummy]

I find that,too. The LT1 in our B-body cars, and our Duramax in our GMC get great mileage at just under 2000 rpm cruise speed. Much over that, and you can watch the gauge move. It seems to be the same with the LS3 in the Tahoe, although just about any speed under 2k with a steady throttle control reaps good results.