mpg z71

[scatesracing]

What kind of mileage is everyone getting with there z71s? I knew my 2002 was getting bad but i took time to figure on this last tank. 9.1 mpg. It runs so good its hard to belive anything would be wrong. I think i might throw a set of o2 sensors in it see if that helps. It only has 100k miles on it

[69gmcc10]

Ethanol percentages in fuel go up in the winter to help with emissions, that might be your problem.

I would leave the O2 sensors alone and get an air filter, a bottle of fuel system cleaner and a custom tune for a better use of your $$$.

[Blown06]

My 2006 with a 5.3 and 4:11 gears gets about 15 ~ 16 on the highway. Was closer to 20 mpg with the stock 3:42's.

[scatesracing]

I hate to think a little Ethanol would cut the mileage in half. its also never done this any other winter.

[69gmcc10]

Originally Posted by scatesracing

I hate to think a little Ethanol would cut the mileage in half. its also never done this any other winter.

Ethanol is a cruel and unpredictable mistress. By law, in the winter here the "only!" fuel you can buy is ethanol and in my 6.0 my economy in town drops from 13ish to between 8-9. Also other things to think about other than just crappy crappy ethanol blended fuel is idle time to warm up. Sure, it doesn't take much fuel to sit and idle, but with the extra time to warm up the engine, the computer to cut back the fuel after initial start up and the amount of time you should take before driving in real cold temps all have an effect on economy.

I would try some sea foam in the fuel tank (cleans o2 sensors and injectors), clean the MAF sensor with "MAF cleaner", and check my air filter. All that stuff is cheap, good o2 sensors are expensive in comparison. But no matter what you do you will still be running crappy, crappy fuel with ethanol in it and in cold temps probably a little water from condensation.

[scatesracing]

Its just weird. it runs great! My 08 and my 99 still seem normal. Ill try some sea foam. the air filter is new. if that dosnt do it I am getting ready to buy HP tuners for my ls swap 69. I may get it sooner to find the problem on this truck.

[kaycee]

Did you change gas stations ? I used 1 that was allways a cent or 2 cheaper than anyone else, started using a different 1 and seems to run better. I don't know maybe it's just me but something changed . Are you running the low octane run some of the super through it.