Horrible Gas Mileage

[Vinsanity]

Sorry if this is the wrong section. Moved if needed.

2013 Tahoe with the 5.3 all stock besides a SLP exhaust delete. Oil changed every 4k and replaced the air filter with a k&n. Over the last approx 10,000 miles the truck has had very bad mileage. I was never one to check my MPG but I used to get about 300-350 miles on a trip. Now it struggles to even get 200 miles. I switched back to using 91 because that seems to help. The car is mixed between highway and streets.

Any ideas what it could be?

 

[wjburken]

Sorry if this is the wrong section. Moved if needed.

2013 Tahoe with the 5.3 all stock besides a SLP exhaust delete. Oil changed every 4k and replaced the air filter with a k&n. Over the last approx 10,000 miles the truck has had very bad mileage. I was never one to check my MPG but I used to get about 300-350 miles on a trip. Now it struggles to even get 200 miles. I switched back to using 91 because that seems to help. The car is mixed between highway and streets.

Any ideas what it could be?

Any lights or codes?

 

[Vinsanity]

Any lights or codes?

Nope. No lights or codes.

Should also mention I have 22's on the car. But I've had those on since I got it.

 

[Big Mama]

How’s your tire pressure? When was the last time the plugs were changed/checked? They can tell you a lot. You may not have a light on but may have an intermittent code. If you know anyone with a Tech2 they can read live data. Clean your filter and TB too.

 

[avalonandl]

Ok when you say bad mpg whats the actual number. You need to get actual mpg over SEVERAL tanks. You mention NO MPG.....

I get 14 mpg around town FWIW

 

[wjburken]

Nope. No lights or codes.

Should also mention I have 22's on the car. But I've had those on since I got it.

How many miles on the vehicle?

What grade/alcohol content of fuel are your running?

 

[Doubeleive]

could be your catalytic converter/s going bad, mine dropped to 8mpg for 2-3 months before the light finally came on, replaced the cat's and now it's back to 10+ still relatively poor mpg but it's a xl, awd 6.2l and I drive it like I stole it, so.....

 

[swathdiver]

Sorry if this is the wrong section. Moved if needed.

2013 Tahoe with the 5.3 all stock besides a SLP exhaust delete. Oil changed every 4k and replaced the air filter with a k&n. Over the last approx 10,000 miles the truck has had very bad mileage. I was never one to check my MPG but I used to get about 300-350 miles on a trip. Now it struggles to even get 200 miles. I switched back to using 91 because that seems to help. The car is mixed between highway and streets.

Any ideas what it could be?

Did you oil the K&N filter? Oil can coat the mass airflow sensor and even affect how the O2 sensors read.

Do you buy fuel from the same station and same pump? Can you check your alcohol content? It may need to be reset. If you're on the Treasure Coast of Florida, I could reset it in 5 minutes.

 

[OR VietVet]

Yep, clean that MAF and throttle body and then check over several tank fulls and do the basics as has been said.

 

[HACK BLOCK]

what's the driving condition like where you live? I ask because for years I got bad Mpg but just accepted the fact that the speed limit is 25 and lucky if I can go more than 300 feet before I hit a stop sign it red light