I just bought a new 2007 VortecMax with Active Fuel Management. The best i have seen, and mine is not broke in yet. 17hwy/ 14city. But like i said, i an only using the computer in the truck to determine that. But i did not buy it for fuel economy. Just for towing and power.

 

I also have the 6.0 Max in a extended cab 4X4and in 1300 miles it has averaged 14.5 by the computer.

 

In a word "sucks"The person who came up with this lame brain idea needs to be slapped!
I am an "old Lady" I do not hot rod. I get the yyo-yo mileage because this stupid engine spends all its time see-sawing up and down the hills around here 4 down hills 8 up hills. so the IS NOT any mileage improvement with this engine. I think as far as mileage goes I should have keep my 04 silverado extended cab. This engine was not thought out well or only tested in dead flat test areas. Oh yea my mileage 10-12 city maybe 16 on the road if there's no traffic. I'm looking for a way to "turn off the "fuel management"

 

Actually the AFM provides the most significant fuel economy improvements during moderate speed and mountainous terrain driving conditions.


I'm fairly certain that the AFM is not responsible for any of your MPG inconsistencies.

 

I drive the same roads, same times of day, same conditions as when I had my 04 Silverado (5.3 with 3.73)but that good ole truck gave me 16-17 in TOWN. 19 on the interstate. Any ideas what else could be effecting the MPG?????

 

How many miles did you have on your old truck?

How many do you have on your new Silverado?
What size tire/wheel on your new one?

 

I had about 45000 mile on the 04 Silverado and the new 07 has 6,000+ on it. So the engine should be "broke in". It just seems like no matter how "easy" you manage the gas. the engine itself defeates the mileage by switching so easily to 4 cylinders (when the old engine just "coasted" when you let off the gas.) then lo and behold when you hit the bottom of a hill or go into a curve it "lunges" into 8 cylinders. Our hilly terrain highways lend themselves to cruise control but the engine does not. This engine should have been made an OPTION not put on all trucks. Some areas of the country do not lend themselves well to this sorry engine. The rest of the truck is great but you sure can't drive this truck past ANY gas station. IT WANTS TO VISIT THEM ALL![]

 

PS to above note:
I had 16's on the old truck and 20's on the 07

 

is there anyway to bypass the AFM with a programmer so it does not go to a 4 banger?

 

My 2009 1500 ext/cab 4X4 5.3 4speed automatic AFM gets 13.7 average in the last 7400 miles.....looking to trade for a diesel.......The best mileage 15.2 HWY For a Tank