Fix for trucks dump in fuel economy?

[CadeO]

So I have 12 2500 with 5.7 and when I first got it back in November it had 12mpg and recently it dropped to around 8 all I've done with it is get both bumpers replaced and got it leveled. Is there anyway to improve its mpg?
(I've also got a cai but I've haven't had the time to install it)

Sent from my SM-G960U using Tapatalk

 

[JohnnyMac]

How many miles on it? How many miles have you put on it since you bought it? Is it throwing any codes? Might be as simple as just the fact you're running winter fuel now which causes a little drop in MPG. Did you get bigger tires with your level? Did it slowly decrease or did it suddenly start getting 8? A plugged catalytic converter will cause a drop in mileage, but you'd probably see some performance degradation as well and it would have probably been slowly coming on. A bad batch of gas would be sudden. You could dump a couple bottles of fuel additive in to maybe see if that helps. If you just want to improve mpgs in that beast, it mostly comes down to driving habits. You might be able to get a little help by plugging a tuner into it, but a 5.7 hemi in a heavy duty 2500 truck is not going to ever get good mileage. All that said, 8mpg seems like there is a problem unless you drive super aggressively.

 

[ThunderMug95]

^^everything above and also realize when you leveled the truck you increased the drag on the truck at speed. Now the front cross section is a bigger, less aerodynamic area. If the bumpers were aftermarket moose killing beasts, then you may have added several hundred pounds as well. Also, if you havent already done so do the math to figure out mpg, dont rely on the dash readout.

 

[Quyonmob]

Front bumpers have huge impacts on aerodynamics.

I pulled the lower plastic valance off my Sierra, cost me 2mpg @70mph.

 

[CadeO]

How many miles on it? How many miles have you put on it since you bought it? Is it throwing any codes? Might be as simple as just the fact you're running winter fuel now which causes a little drop in MPG. Did you get bigger tires with your level? Did it slowly decrease or did it suddenly start getting 8? A plugged catalytic converter will cause a drop in mileage, but you'd probably see some performance degradation as well and it would have probably been slowly coming on. A bad batch of gas would be sudden. You could dump a couple bottles of fuel additive in to maybe see if that helps. If you just want to improve mpgs in that beast, it mostly comes down to driving habits. You might be able to get a little help by plugging a tuner into it, but a 5.7 hemi in a heavy duty 2500 truck is not going to ever get good mileage. All that said, 8mpg seems like there is a problem unless you drive super aggressively.

I got it with around 35,000 miles and it got 43,000 now, no codes have been thrown since I've had it, no the tire are stock size, it's also felt very sudden. I'll try the fuel adivited.
Note: I have a friend with a 18 2500 with a 6.4 who got the exact same parts as me and only lost a mile.

Sent from my SM-G960U using Tapatalk

 

[CadeO]

^^everything above and also realize when you leveled the truck you increased the drag on the truck at speed. Now the front cross section is a bigger, less aerodynamic area. If the bumpers were aftermarket moose killing beasts, then you may have added several hundred pounds as well. Also, if you havent already done so do the math to figure out mpg, dont rely on the dash readout.

Aculally My truck said I had 10
which threw me off so I did the math and found I'm only getting around 8

Sent from my SM-G960U using Tapatalk

 

[dexter]

So I have 12 2500 with 5.7 and when I first got it back in November it had 12mpg and recently it dropped to around 8 all I've done with it is get both bumpers replaced and got it leveled. Is there anyway to improve its mpg?
(I've also got a cai but I've haven't had the time to install it)

Sent from my SM-G960U using Tapatalk

Is that City or Highway driving?

Hand calculated or computer calculated?


The CAI will probably cost you more mpg ... cold engine; more gas.

 

[CadeO]

Is that City or Highway driving?

Hand calculated or computer calculated?

Highway and on my other reply I mentioned about calculated the mpg

Sent from my SM-G960U using Tapatalk

 

[dexter]

Highway and on my other reply I mentioned about calculated the mpg

Sent from my SM-G960U using Tapatalk

That 12 mpg was even bad.

I have a 6.4 I get
17 highway
12 city
9 towing on highway

I think, as others have said, you killed the aerodynamics of the truck and added weight.

There may have been another problem, e.g. alignment contributing to the poor mpg.

 

[CadeO]

That 12 mpg was even bad.

I have a 6.4 I get
17 highway
12 city
9 towing on highway

I think, as others have said, you killed the aerodynamics of the truck and added weight.

There may have been another problem, e.g. alignment contributing to the poor mpg.

Yes I went in know that the economy would suffer I just find off that it lost 4 miles

Sent from my SM-G960U using Tapatalk

 

[JohnnyMac]

I got it with around 35,000 miles and it got 43,000 now, no codes have been thrown since I've had it, no the tire are stock size, it's also felt very sudden. I'll try the fuel adivited.
Note: I have a friend with a 18 2500 with a 6.4 who got the exact same parts as me and only lost a mile.

Sent from my SM-G960U using Tapatalk

Did it happen right after the lift? If it was sudden and was a while after the lift, then something goofy is going on. Does it run good otherwise, or is there any poor performance?

 

[CadeO]

No Its been about 2 months since I got the lift done and the economy drop happened over this week and it still runs pretty strong. I've also put a additive in the fuel to see if that helps


Sent from my SM-G960U using Tapatalk

 

[JohnnyMac]

Yah, I've lifted every truck I have ever owned and usually put bigger tires/rims on it at the same time and it never dropped 33% of my mpgs. I think you might start looking at some out of the normal things. For one, bad fuel could do it, but usually that also has poor performance. Hopefully the additive will help. Might also jack up the back end and make sure the E-brake didn't hang up on one of your rear wheels and is dragging. Let us know if you find something.

 

[Pull Ya]

^^^ I have leveled all 4 of the 4th Gen trucks I have had and only lost about 1-2 mpg. on any of them. The amount of mpg you have lost I would look elsewhere, IMHO leveling ain't the whole problem. When was the last time you changed plugs?
Jay