2008 GMC Yukon Denili

[BG1988]

The 4.8L is worthless unless you put a giant turbo on it. No power and the same fuel economy as the 5.3L. There’s a reason it was discontinued.

i got pretty good mpg in my silverado 1500 4.8L long bed.. 18/21 on the highway got rid of it cause i did not like the cost of the registation

 

[thompsoj22]

Welcome to the forum, This is where you will find just about every answer you will need to repair anything that can/will go wrong with your Denali. However, You have asked how to get better milage from a vehicle that has a 31 gallon gas tank for a reason! I have the same vehicle and get about 11 around town with ac blasting and as much as 19.4 highway with the cruise set at 74 on hwy 40 east from cali to sedona on a single tank! 504 miles! We love our road limo and burn only chevron premium. The cost difference between a tank of chevron premium and arco regular is $11, That is one less fast food meal every fill up. This is proof that driving a gas guzzler can be healthy! lol

 

[Burkard]

Welcome to TYF!

*Denali

Aftermarket parts to help improve gas mileage? Hmmm... There's a custom tune, narrower tires on smaller and lighter wheels, a 3/4+ drop, roof rack delete, weight reduction...

It's not recommended, but you can run cheaper gas. Just don't tow anything heavy, avoid hills, and stay outta the throttle. Honestly, you have the wrong vehicle to be concerned with saving a few pennies on fuel! You'd spend more on modifying it for an extra 1-2 MPG than what it may save you in this lifetime.

Thank u. For the info.

 

[Burkard]

What are you getting for fuel mileage now? How many miles are on it?

Edit: Also, Welcome to the forum from Iowa.

Im getting 8 to 10 mpg and it has 55000 miles on it.

 

[wjburken]

Im getting 8 to 10 mpg and it has 55000 miles on it.

That seems a little low for sure. We got 12-14 in town on our 2008 Denali XL and around 17-18 on the highway with 100K on the ODO.

Might check your air filter, clean your MAF sensor, clean your throttle body, make sure you have the proper amount of air in the tires, etc.

Might see if you have a plugged cat, but at 55K, that would be a little bit of a premature failure.

Do you have a scan tool that shows you stuff like fuel trims and O2 sensor readings?

 

[donjetman]

We are getting 17+ mpg running premium unleaded and doing mostly hwy driving. When we run mid grade unleaded we get 16+ mpg.

 

[HiHoeSilver]

Im getting 8 to 10 mpg and it has 55000 miles on it.

Whoa, there tiger. You have an 08 with 55k? That's a good start! Let's see some pics! Any knowledge of maintenence history?

I'm with Wade here. Start basic. Air filter, tire pressure, oil condition, check for brakes dragging, etc.

Then the scanner. The data doesn't lie. You can get pretty nice Bluetooth ones for fairly cheap these days.

 

[Burkard]

Thank you for suggestions. I did notice the brakes stick alittle after you let off the brakes it seems like a small delay with brakes but thought it was normal. This weekend gonna change the air filter and pull plugs. I drove it to Orlando Monday night and noticed on highway. I was getting 19- 20 mpg doing 70 mph. Its nice to know the flue management system was working. I will get some pictures and post them. I love these yukons, the one I had before had a 4.8 in it and it had 310,000 miles on it and was going strong. But didn't have 3rd seat, and with 3 kids I had to go with the 3rd seat. Thank you for all the suggestions

 

[Burkard]

That seems a little low for sure. We got 12-14 in town on our 2008 Denali XL and around 17-18 on the highway with 100K on the ODO.

Might check your air filter, clean your MAF sensor, clean your throttle body, make sure you have the proper amount of air in the tires, etc.

Might see if you have a plugged cat, but at 55K, that would be a little bit of a premature failure.

Do you have a scan tool that shows you stuff like fuel trims and O2 sensor readings?

No scan tool, will go get one this weekend, meaning to get one. Have to get a scripped screw out of the air filter housing. And gonna pull plugs to look at them. I know the fuel management system is working drove to Orlando the other day and was getting 19-20 mpg doing 70 mph. I was glad to know that was working. Thank you for your time and input very appreciated. God bless all of you'll for helping others with their problems.

 

[Burkard]

Welcome to the forum, This is where you will find just about every answer you will need to repair anything that can/will go wrong with your Denali. However, You have asked how to get better milage from a vehicle that has a 31 gallon gas tank for a reason! I have the same vehicle and get about 11 around town with ac blasting and as much as 19.4 highway with the cruise set at 74 on hwy 40 east from cali to sedona on a single tank! 504 miles! We love our road limo and burn only chevron premium. The cost difference between a tank of chevron premium and arco regular is $11, That is one less fast food meal every fill up. This is proof that driving a gas guzzler can be healthy! lol

Thank u. Will start with the air filter then work my way for. Cheapest up. Thanks for your time and input. Im glad there is a place to get ideas on your truck before taking to a shop and costing me a fortune. God bless you'll.