2012 1500 Silverado 5.3L Gas Mileage

[alstairs]

I have a brand new LTZ 1500 Silverado with 5.3L engine. I have been really disappointed to date (2 weeks) with the fuel mileage. As a brief test, I tried turning on the 4WD High. The AFM seemed to be on more often, turning the engine into 4Cyl mode. Also, I reset the fuel mileage before doing this, and my average fuel mileage was better.

 

Is there anyone out there that has seen this, and is there a fix? I could be way off, but it almost seems like a programming error in the AFM. I can't understand why the fuel mileage would be better in 4WD, and the AFM was switching into 4Cyl mode at a noticeably longer period of time. (I checked it on the same stretch of road i drive every day...)

 

Thanks for any help, this is a great site.

 

Al

[Jsdirt]

I find most people all have different ways of figuring mileage .... and you usually will come up with different answers. I don't even go by the DIC - it's always way off. You need to fill up several times at the same station, on preferrably the same pump, so when the pump kicks off you know it's filled up the exact same amount each and every time. Then of course divide miles on your trip by gallons - but this only works if you remember to reset trip upon fillup.

 

My DIC says 14.7, because it's factoring in all the times I've towed cars & trucks with the car hauler. No trailer, I get 15.5 -15.7 consistently, with '07 5.3 flex, 4x4, 4L60E tranny, w/ 3.73 G80 rear. Winter blend fuel knocks 1 mpg off that or more.

 

Another factor is where you live. You wouldn't believe what some states pass off for fuel. MA offers you no choice but ethanol-diluted fuel. It's supposed to be for "clean air", but think about it - millions of vehicles getting 2-3 LESS mpg results in more gasoline tax revenue for the state, and a windfall for the oil company. Your selling cheaper fuel for the same money, & "cutting" it with ethanol - it's basic theft, but nobody says anything about it because the money rolls in.

 

It's posted on the pump as "10%". That kills your mileage BIG time. Now, with the flex engine, you have the capability to see "alcohol percentage" with a scan tool. I've never run E85 in the truck in the 5 years I've owned it, yet, I've seen alcohol percentages range from 15% all the way up to over 20%!! I can feel seat-of-the-pants power loss when I get an exceptionally crappy 20% ethanol batch. Mileage will also drop to around 13 mpg. This is also why my business is getting away from automotive repairs and doing more motorcycle, boat, lawn equipment repairs -- that percentage of ethanol wreaks havoc with small engines. Clogged carbs, and in worst case, seized engines that were jetted for normal fuel.I clean probably 100 carburetors per season, including my own ... and I drain them! The fuel is garbage here.

[markw8]

You need 5000+ miles before worrying about gas mileage. Also if your looking at the DIC for current mileage, you should watch it over a couple of tanks.

 

Mark