01 Silverado problems

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Paul04_619, Dec 10, 2012.

  1. Paul04_619

    Paul04_619 New Member

    Hi guys, im new to the forum and I have some questions. My truck is a Ext cab 01 Z71 5.3 auto. I bought it earlier this year and all summer long averaged 16-17 MPG no matter what. Over the last couple months iv been seeing 13-14 and i'm really not understanding the drop because im driving the same route every day. I was blaming it on warming it up every morning but i drove it the last two days without warm up and checked the mileage at 14.3. Im not looking for Prius fuel mileage but a drop in gas mileage tells me something bigger could be coming. Any information would be much appreciated.
  2. silverhobey

    silverhobey Rockstar 3 Years 500 Posts

    welcome from a Canadian Member ...............wonder if it is tune-up time ???
    good luck in whatever you may find out on this site....there are some pretty
    smart cookies around here ......Brian:glasses:
  3. Paul04_619

    Paul04_619 New Member

    Thanks Brian. I think it may be tune up time myself, kinda odd that it was seemingly all of a sudden. Also any idea on how to bypass those pesky o2 sensors? Im looking to delete my cats.
  4. silverhobey

    silverhobey Rockstar 3 Years 500 Posts

    hey Paul, maybe ask Muffler Shop guys about leaving the
    o2 sensors alone....they might not need taken out or by-passed @ that age ....
  5. Paul04_619

    Paul04_619 New Member

    I am the muffler shop guy haha. Im a welder so i always do my own exhaust installation.
  6. silverhobey

    silverhobey Rockstar 3 Years 500 Posts

    too funny..go figure....have a good day Paul.....Brian
  7. j cat

    j cat Epic Member 5+ Years 1000 Posts

    the O2 sensors help the computer adjust the mixture ratios. removal will lower MPG. with the stock oEM exhaust on these trucks the engine power created is well sized on the exhaust.

    cold weather always lowers MPG. with temps below 32 deg F you will see your kind of MPG loss.

    when it gets below 25 deg f I use a plastic shield in front of the radiator to reduce cold air flow. it also reduces road chemicals from damaging the engine compartment.this helps to reduce cold weather MPG loss.

    warm weather my 2000 5.3L LT ext 4X4 truck gets 18-19 mpg. cold weather like below 25 deg f about 14-15MPG. been like that since new 4/2000.......

    - - - Updated - - -

    forgot to say that 5-30wt synthetic works great when the temps fall below 10 deg f.

    no way dino oil when its below zero F....engine sounds like its going to explode.
  8. buckmeister2

    buckmeister2 Rockstar 4 Years 100 Posts

    is there any chance your area has a mandate to switch to oxygenated fuels during fall/winter? many parts of the country, including many rural areas, require the change, date dependent upon typical weather, but often Nov. 1. The additives they put in the gas will sometimes cause a 2MPG loss, depending upon the vehicle.

  9. j cat

    j cat Epic Member 5+ Years 1000 Posts

    your winter summer formulations explaination could be a factor. summer gasoline is more expensive because the formulation does not have butane added. the summer blends are produced to not boil off with the high temps. as winter causes the temps to drop the gasoline needs butane to get the gas to VAPORIZE AT THE LOWER TEMPS.

    butane is a cheaper additive so the cost to produce winter gas is lower..

    It is reported that using summer blended fuels in the winter can cause hard cold starts.

    could be the butane used lowers MPG.

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