I have an 07 Tahoe with the active fuel management and i get the worst gas mileage, i get an average of 16.4. I do mostely highway driving and try to take it easy. I have a Magnaflow cat back thinking it would help a little but nothing. I have friends with Yukons and no fuel mangagement and they get 24 can this be tuned out? or could there be an issue with it?

 

They aren't getting 24mpg in a Yukon. No way. No how.

 

I have a friend with a 2004 Tahoe 5.3L with 3.73 gears getting 18 mpg on the highway and he has a custom tune in his with no AFM.

 

I tuned AFM out and I i'm getting about 19-20mpg on the freeway and 15mpg city... The best part though is not having to hear the dreaded exhaust drone...

 

My wife drives a 2007 Tahoe. Best highway mileage has been 18.2. Pretty sure she had a tail wind because it usually runs around 16.5. With a supercharger and cam etc on my truck I can still do 15. I think the DOD does nothing. When my truck was stock, just tuned, and DOD disabled I could still get better mileage then hers.

 

My truck seems to do good with AFM. Sometimes I think the 6.0 does better with AFM than the 5.3s do. In city I get 16-19 and 22-24 on hwy. My best was 26.7 driving through New Mexico and Arizona.

Most of it depends on the gas you get too. That ethanol crap does nothing for you. I filled up in Washington state with 92 octane 10% ethanol and barely made it through Oregon driving 65mph. I got 15.4mpg!

I just turned my DoD off with a Diablo tuner because I have heard about other people getting better gas mileage running all 8 cylinders so I will see how it goes. I really can't imagine any more mpgs than what I have been getting though.

 

So, I'm sure GM went through all the trouble of designing and engineering a package that does nothing. I guess they wanted to include more parts in their powertrains to fail.... Right?
If it didn't work, they wouldn't risk including it. Cost would outweigh benefits.

Everytime you hear a mileage claim by anyone, take it with a grain of salt. For many, if they attain a mileage number twice (or never) that's good enough for them. They are then convinced that their vehicle defies the laws of thermodynamics and physics in general.

 

I have a brand new (2k mile) CCSB with the 5.3 - I have gone to Mich and Cols on long trips - I watched the AFM kick in and out on the trips - best yet 20 mpg at 75 mph

 

Unless it is a sales gimmick

Good Point, some might just be going off the mpg reading off the cluster...

 

Well, I'll have to disagree with you with some data but this is a car, my wife's G8 GT. The sticker says 16 city and 24 hwy. After her driving it stock for about 6 weeks and getting some data (stock), it was more about 18.2 city and 23.4 highway. Only mods were tuning with AFM disabled and Homemade CAI and the car has repeatedly returned 18.5 to the most recent 19.7 city mpg while the DIC showed 18.7 and we have seen on average 26 mpg with a max of 28 mpg on the hwy. These are not DIC numbers, these are calculated numbers and the gas was about as even as I could get it, filling the gas to the neck everytime.

But again...this is a car to so....


GM has used this for CA/FED because the gov't wants all vehicles in the fleet to have a certain mpg rating by 2012 or something like that. I believe the mpg reading was 21?