just bought 05 5.9 all stock would like to know how to get best fuel mileage out of my truck without hurting stock parts

 

Lose the muffler...

I was surprised how much power and economy that one item alone had been costing me.

My muffler rusted and fell off. Instantly ~2mpg gain and a bit of extra power to boot. I booger fabbed a piece of 4" straight pipe in the mufflers place as I wanted to see if it was in my head and while I figured out exactly what I was going to do next. (stock muffler and muffler back pipe cost more than an MPRB complete system)

The bad: I get a horrible drone in the cab at 2000 to 2500 rpm with a load on (camper up a long hill or accelerating onto the freeway) just puttering about the sound isn't that bad.

Yes, I am going with an aftermarket exhaust system. That should help with the fuel economy and do a little for the sound as well.

 

Smarty Jr. will help

Proper tire inflation
Change the Fuel and Air filters (if you haven't yet)
Take off slow from stop lights and signs
If you have a manual trans, shift about 1800 to 1900 rpm

 

I added a muffler for a total of two aftermarket.

Do a title search on each of the words: economy, mpg, mileage.

 

There are a lot of things you can do to improve mileage. Some are are expensive mods, and will probably never pay off. And some are cheaper, and pay off quickly. Do a search here and you'll find a couple of hours of reading.

The number one thing to do is slow down. These trucks are really speed sensative. Drive it like a little old leady going to church and you get much better mileage than hot rodding.

 

Keep the stock tire width if your really going for mileage. You don't mention in the post or your signature Stick or auto. This will get you more detailed responses. One of the biggest milage losses I experianced was the 35x 12.5 tires. Now I'm OK with the tire because they help the stick shift final gear ratio so I can run about 65 under 2K rpms which helps MPG.

 

little things like braking. dont brake at the last second. let the truck coast to the stop sign. dont punch it everytime you take off...

 

Great replies above.

I'd also open up the intake side of things and ditch the stock airfilter and go with a free flowing option. I ran a Scotty Ram Air III on the 04.5 prior to moving to twins. Several options out there to ponder. I like the Megacannon on the 09.

Couple of other items include a street cam and larger charge air cooler. The cam is a fairly costly upgrade, and unless you are driving a lot and keep the truck for a long time, it probably won't pay for itself.

 

Learning how to drive for economy has the greatest payoff. Given a stock truck no aftermarket changes will even come close. Start with recording every gallon used, and all dollars spent, by the truck. Spending money to "save" money is a long way down the road after maximizing current specification fuel economy.

 

Synthetic lubricants, clean air filter & a fresh fuel filter are a good place to start.

Next make sure your tires are inflated to the propper pressure for the loads carried. When replacing tires choose the correct tire profile & size for the driving conditions.

Slow down while crusing & keep RPMs below 2000 at all times & preferably below 1850 rpm.

Drive defensively, anticipate stops, accelerate slowly & smoothly.

No excessive idling & stop using the **** drive thru. Turn your truck off & walk inside to do your banking & get your coffee or burgers.

All of these items have minimum cost & will yield improved fuel economy.

If you plan to keep the vehicle for many years then a programmer like a Smarty is justified as it will pay for itself in fuel savings over the long run.

 

How much fuel are you really burning by idling in a drive thru for a minute or two? Thats like shutting the truck off while sitting in traffic.

 

It's the small stuff that adds up. There is nothing, nothing good that comes from idling any where, any time. And, no, it's not like shutting it off in traffic, which, besides being illegal, is a function of traffic control not driver choice.

Driving economically means making hard & fast rules. No idling is high among them. Driver choice means the least fuel for the most work. Idling means truck deterioration, in general, which is within the larger picture of best use of fuel: lowest cost per mile under all conditions.

How many "minute[s] or two" over the next ten years? How much faster will the truck reach serious repair bills in time or miles?

Most of us (more than 90% by one study) can easily be predicted: where we will be, and when. The usual rounds of work, shopping, etc. Think it through and make the changes: Eliminate one round of short trips by combining it with another. Never drive on Sunday. Do whatever you want to make changes that work. "No idling" works in all times and places. Just learn to park for easy ingress & egress.

It's the same as avoiding full lock turns: a mistake has been made that the truck will now have to pay for (ultimately, me).

.

 

Quick question Rednax. Why shouldn't you make full lock turns?

 

A vote for the Smarty jr. here too. I don't know if it was timing or what but I got an instant mileage and power increase.

I don't believe for a minute that an exhaust could help my truck being an 06 model. All the tests and reports I have ever read show that there is no benefit to replacing the exhaust system. No additional power, no reduction in back pressure. I'm not sure about an intake, but I sure don't pull down my pressure sensor on the intake box with a stock filter. And I'm much more concerned with high silicate levels in my oil than some fancy air filter claiming to let my engine breathe better.

But that all said, I firmly believe removing a muffler will help 90% of drivers increase their mileage! In fact removing the entire exhaust system would be even better! Just the noise alone keeps a driver off the throttle as much as possible, and that will add considerably to the mileage.

 

I agree but went about it a bit differently. I removed the silencer ring and baffle in the intake tube. This allows me to hear more turbo noise which I like. It also alerts me to when I may be using more throttle and reminds me to slow down, especially when pulling.