Help!! Bad Gas Mileage

[mr tahoe]

guys please help im getting really bad gas milage on my tahoe driving habits are the same nothing really changed other than she is not as responsive as she used to be, she is a 2008 rwd tahoe about to hit the 400 thousand k
No problems other than that cleaned the throttle body and just changed my air filter

 

[swathdiver]

Check for leaking fuel lines. Does the engine sound the same?

My first car got 6mpg. After a few weeks it got 4mpg then 2mpg. Finally, I could smell and then see the puddle when idling in my driveway. After the new hoses, 18mpg!

 

[Kenny D]

Sticky calipers? Leaky fuel tank or lines? When was the last time you gave it a tune up?

 

[mr tahoe]

No fuel leaks, brand new calipers rotors and pads a week ago to be exact. Haven't done a tune up honestly still the same spark plugs since i got it.

 

[Tonyrodz]

No fuel leaks, brand new calipers rotors and pads a week ago to be exact. Haven't done a tune up honestly still the same spark plugs since i got it.

I'd def check the plugs. I bet just changing those will give you some improvement.

 

[CrashTestDummy]

What is "really bad gas mileage" in your case?

Our '10 started dropping MPG, so I started doing all the usual stuff, plugs, wires, clean the MAF and TB, new air filter, etc. it made incremental improvements, at best.

Our Tahoe seems really sensitive to tire pressure, oh, and my wife's left foot!

While it may not be an issue, you should check your fuel pressure regulator. Never had an issue with the Tahoe, but had a 95 Caprice that ruptured the FPR, TWICE. The car ran okay, but would barely pass emissions, and idled oddly.

Pull the vacuum hose off the FPR and make sure you don't see or smell gas. If the FPR is leaking internally, your mileage will suffer.

 

[swathdiver]

Check those brand new calipers. Since that is new since the problem started, start there.

 

[mr tahoe]

It was happening before the new braking components

 

[mr tahoe]

Im gonna start with the spark plugs and see where that takes me any recommendations?

 

[Kenny D]

Go with what came in it from factory. IMO