MPG increase help

[dabeech]

I have a 07 Yukon XL 2500. Only getting 10 mpg. Put in new plugs and air filter. Still seems to have a slight hesitation at idle. Clogged fuel injector? Wife drives the rig and she drives like grandma. Did some hwy driving and still only 10 mpg. Suggestions?

 

[mikeb33]

Mostly around town and much "spirited" driving, I get an average of 12.5.

 

[Conor]

10mpg is pretty low. Have you tried cleaning the throttle body? How many miles?

 

[rogersinsel]

I have a 07 Yukon XL 2500. Only getting 10 mpg. Put in new plugs and air filter. Still seems to have a slight hesitation at idle. Clogged fuel injector? Wife drives the rig and she drives like grandma. Did some hwy driving and still only 10 mpg. Suggestions?

Is it completely stock?

---------- Post added at 11:22 AM ---------- Previous post was at 11:19 AM ----------

I have a 07 Yukon XL 2500. Only getting 10 mpg. Put in new plugs and air filter. Still seems to have a slight hesitation at idle. Clogged fuel injector? Wife drives the rig and she drives like grandma. Did some hwy driving and still only 10 mpg. Suggestions?

14 city- 18 highway is sticker mpg. 4wd.

 

[dabeech]

Is it completely stock?

---------- Post added at 11:22 AM ---------- Previous post was at 11:19 AM ----------



14 city- 18 highway is sticker mpg. 4wd.

Yes, all stock. Just put some new plugs and air filter in. It only has 54k miles on the truck. Mostly around town driving, but even when I go on a long hwy drive it's only 10 mpg.

---------- Post added at 12:03 PM ---------- Previous post was at 12:02 PM ----------

10mpg is pretty low. Have you tried cleaning the throttle body? How many miles?

Never tried top clean the throttle body. Is it hard or a quick weekend project?

 

[Mr. B]

Try running a few fuel injector cleaner bottles through it.

Maybe a bad O2 sensor. That can cause a big mileage drop.

 

[Conor]

Yes, all stock. Just put some new plugs and air filter in. It only has 54k miles on the truck. Mostly around town driving, but even when I go on a long hwy drive it's only 10 mpg.

---------- Post added at 12:03 PM ---------- Previous post was at 12:02 PM ----------



Never tried top clean the throttle body. Is it hard or a quick weekend project?

Yes it is easy and can't hurt. A bottle of Lucas Oil fuel injection cleaner couldnt hurt either. Also, make sure your tire pressure is where it is supposed to be. I run mine around 5 lbs below max psi to get the best mpg possible. The harder the tire is the less rolling resistance it will have. Just be carefull not to over fill, and also keep in mind that a warm tire will read about 5lbs more pressure than a cold tire.

 

[dabeech]

I called the GMC dealership. They said that the check engine light would come on if it was a bad o2 sensor.

---------- Post added at 12:59 PM ---------- Previous post was at 12:58 PM ----------

Any online instructions to show how to clean the throttle body out?

 

[young_2010_chris]

I called the GMC dealership. They said that the check engine light would come on if it was a bad o2 sensor.

---------- Post added at 12:59 PM ---------- Previous post was at 12:58 PM ----------

Any online instructions to show how to clean the throttle body out?

does it have a 6.0?

mite need to change coil packs and wires to im sure it wouldnt hurt

 

[dabeech]

yes it's a 6.0L. Changed the plugs, but not the coil packs and wires

 

[puckhead]

Once you do get it figured out, i would look at getting a CAI. It is a rpetty big truck to move around too. but 10 is low

 

[Mr. B]

A scan cable tune from Blackbear would 1) improve your mileage, and 2) let Justin look at your pre-tune data to see if he can help narrow it down. You have to give a couple deposits to him, but in the end it is only like $250 for the tune.

 

[mikeb33]

I just got back form a 2,500 mile trip. I averaged about 16mpg. I was doing 80-85 mph for a great part of it, and maybe 300 miles of around town driving in there too.

 

[BC Lightning]

A scan cable tune from Blackbear would 1) improve your mileage, and 2) let Justin look at your pre-tune data to see if he can help narrow it down. You have to give a couple deposits to him, but in the end it is only like $250 for the tune.

Data is power!! I would data log it to see what everything is reading. Check timing, fuel trims, spark, etc.

10 is way too low, even if you had your foot smashed to the floor every time you got in

 

[phileaglesfan]

I would guess something in the fuel system. Maybe a clogged filter (if these even have one).

 

[dabeech]

Fuel filter is in the gas tank. Cleaned the TB and MAF this weekend. So we will see what happends. Running Lucas fuel injector cleaner thru the tank too.

 

[dabeech]

Anyway to test a o2 sensor to see if its bad?

 

[stevek]

My Denali (6.2) sucks up gas... going by the trip mileage and how much I put in at the pump I'm averaging 10mpg at best. I stopped gassing it unless necessary, accelerating slower, etc but not much better. Should I use Premium or Regular?

 

[Fast55]

Being a 6.2 like my Tahoe or an Escalade, you should never use less than mid-grade or 89. Tune it and it'll help.