Terrible MPG!!

[keenan]

Hey guys, so I've got a 2002 Tahoe 4.8l 4WD. I've had it for a about 3 months and i'm getting terrible mpg. I drive about 90% city and i average 9.5 mpg. When I take it out on the highway I get around 13. Its got 118k miles. Plugs and fuel filter replaced at 110k. It runs great, and i've been keeping it light on the peddle. Anybody have and idea on what I could do to increase it? I don't have that big of a budget. Thanks!

 

[Big Buttons]

Stock sized tires?

 

[keenan]

I think... Toyo a/t open country p265/75r16.

 

[Big Buttons]

Weird. I have same sized tires and a bunch of performance upgrades and I get about 13 city.

 

[keenan]

I also forgot I've got a Superchips tuner installed and using the 87 octane tune and mileage save tune.

 

[Big Buttons]

I have a Blackbear tune using 88oct

 

[NCTyphoonKid]

I also forgot I've got a Superchips tuner installed and using the 87 octane tune and mileage save tune.

any codes stored on the ecm? odd that's its getting that bad of mileage

 

[Big Buttons]

Did it all of a sudden get bad gas mileage? or has it always done this? I realize you've only had it 3 months.

 

[keenan]

No codes and since I've had it its been bad.

---------- Post added at 09:44 PM ---------- Previous post was at 09:38 PM ----------

any codes stored on the ecm? odd that's its getting that bad of mileage

No codes..

 

[afpj]

O2 sensors original? May need to look at voltage waveforms with a scan gauge or something to confirm that they are working okay. They will not throw a code unless their about dead.