5.3 vortec gas mileage question

[ClassicDreamer]

just got my dad 2002 gmc yukon. So far it sucks on gas. Looking for slight improvements to improve MPG. filter? torando thing? thoughts? Mainly got it to tow my 54 truck long distances.

[dwcsr]

Whta is the mileage your getting?

[blackdiesel]

What are you calling sucks? it should get 16-20. Some injector cleaner and a new air filter might help. How you drive it is the biggest part of miles per gallon. Lots of starts and stops are hard on MPG in something that big. Fast starts will really kill it.

[LEEVON]

I've had a load of 5.3's, tahoes, 1/2 tons, 3/4 tons, 2wd, 4wd and the mileage has always been from 12-16mpg. Maybe it's my driving, but 20mpg I've never been able to attain.

To your question, the best bang for the buck is to get a custom tune from somebody like wait4me performance, blackbear, nelson, wheatley, etc. This works even better with supporting mods like long tube headers, intake, etc. Also running synthetic fluids in the entire drivetrain can result in slight gains. Before doing any of this though make sure you have a good tune-up. Fuel filter, plugs, air cleaner, cleaned MAF, check resistance on the coil packs and plug wires, tire pressure and whatever else you can.

Don't waste your money on gimmicks like tornadoes, magnets and crap.

[ClassicDreamer]

Averaging about 12-16mpg. I live in NYC and do most of my driving there. I am thinking about seafoaming the whole motor and running injector cleaner. Definately getting a K&N. I will look into the tuner mods. Then again I came off of daily driving VWs so this seems like a gas drinker.

[LEEVON]

Seafoam is the stuff. Wait until you need to change the oil, then pick up 2 bottles. Put one into an almost empty gas tank, fill up and drive it for a couple hundred miles. Then suck the other up through the brake booster hose into the intake while the truck is running. Basically pour it into the hose until it almost stalls but don't let it, keep going till it's gone. Turn off the truck and let it sit for about 30 mins, then restart and watch the smoke billow! This is the point where you change the oil and it will be cruddy.

Funny thing about the cold air intakes, "general consensus" used to be that they were the 1st and best mod. Times have changed and now all the internet "general consensus" claims they do nothing at all but make noise. They laugh at them on some of the big forums. It's sbunny because they work, I've always picked up mileage and power.

[Keith Seymore]

Originally Posted by ClassicDreamer

... Definately getting a K&N...

Originally Posted by LEEVON

Funny thing about the cold air intakes, "general consensus" used to be that they were the 1st and best mod. Times have changed and now all the internet "general consensus" claims they do nothing at all but make noise. They laugh at them on some of the big forums. It's sbunny because they work, I've always picked up mileage and power.

I am encouraged to see that change in philosophy since I can't see how a new air induction system could help.

I designed the original air cleaner and ductwork for the GMT800 models. We sized them to flow for the largest engine available at the time, which was the 8.1L gas engine (272 g/s at 1" Hg flow restriction, air inlet to throttle body).

The spec for the 5.3 was 225 g/s, so there should have been plenty of additional capacity.

In theory, adding a "free flow" aftermarket air induction shouldn't do a thing.

K

[ClassicDreamer]

keith besides the flow design of the intake would a free flowing filter help?

Leevon, I put seafoam into my old diesel and boy was that a smoke show!

[LEEVON]

Originally Posted by Keith Seymore

I am encouraged to see that change in philosophy since I can't see how a new air induction system could help.

I designed the original air cleaner and ductwork for the GMT800 models. We sized them to flow for the largest engine available at the time, which was the 8.1L gas engine (272 g/s at 1" Hg flow restriction, air inlet to throttle body).

The spec for the 5.3 was 225 g/s, so there should have been plenty of additional capacity.

In theory, adding a "free flow" aftermarket air induction shouldn't do a thing.

K

Keith, glad you chimed in. Just don't go and give the guys at gmfullsize.com any fuel for the fire please! The GMT800 intakes were a definite improvement from the days when flipping your TBI lid would make your truck scream though! Seriously though if you checked in over there you'd be an instant hero and villain all at once.

[Keith Seymore]

Originally Posted by ClassicDreamer

keith besides the flow design of the intake would a free flowing filter help?

No, based on the thought process shown above.

K

[Keith Seymore]

Originally Posted by LEEVON

Keith, glad you chimed in. Just don't go and give the guys at gmfullsize.com any fuel for the fire please! The GMT800 intakes were a definite improvement from the days when flipping your TBI lid would make your truck scream though! Seriously though if you checked in over there you'd be an instant hero and villain all at once.

I think I'll just stay here and hang with my C/K/R/V buds....

[solidaxel]

Thank You for your help.

[solidaxel]

Originally Posted by Keith Seymore

I think I'll just stay here and hang with my C/K/R/V buds....

Do you have any good tips for a 78 Q-jet upgrade?

[Keith Seymore]

Originally Posted by solidaxel

Do you have any good tips for a 78 Q-jet upgrade?

Keep the primary side small and the secondary side fat...

...and keep your foot out of it!



K

[mr48chev]

According to my son who has a 2000 GMC with a 5.3 they don't get much for gas mileage. He has never come out and said what he gets but from what I understand it isn't good and that truck is stone stock right down to the radio and factory wheels.

[foamypirate]

My father's 08' GMC 1500 CCSB 4x4 gets around 20-21mpg highway, but some of that may be due to the AFM (active fuel management). In-town is another story, averaging around 15-16mpg.

[BlueJeep]

18mpg highway with our 03 Suburban Z71 with 130K miles.

[ClassicDreamer]

I just filled up on super. $64 for the tank. Pops said it never got better that 15mpg. WOW nelly!

[cajundragger]

super?

should be putting regular in that thing.

[TwoFiftyShifter]

What size tire? I can get 15 in town and 20 highway in my dad's 07 4x4 1500 extended cab, 5.3l. alot of it is how you drive. However, if you have say 265/75/16's, going to 245/75s will give you 1 mpg almost guaranteed, wont look as good, but that has been my experience.

[85burb]

A cold air with programmer added almost 4 to my friends 03 2500HD 6.0. Some say they do nothing some say they do a lot. His deff helped alot. Went from 10 to 14.

[raycow]

Originally Posted by TwoFiftyShifter

if you have say 265/75/16's, going to 245/75s will give you 1 mpg almost guaranteed, wont look as good, but that has been my experience.

Did you do a speedo correction when you changed the tire size?

Ray