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Silverado Problem

Discussion in 'Chevy Trucks' started by Proscapez LLC, Nov 26, 2006.

  1. Proscapez LLC

    Proscapez LLC Senior Member
    Messages: 293

    I think My truck has an issue with gas mileage.
    I have an 04 Silverado 1500 ext automatic 4-speed 4x4 5.3L.
    the best I have been able to get out of it is 14.1mpg at 70mph,
    traveling non stop on the freeway.
    Does anyone else have the same truck and what are you getting?
  2. lodogg89

    lodogg89 Senior Member
    Messages: 412

    do you have any cover on your bed, of do you drive with you tailgate down. Better speed for a truck is like 60-65 for prime fuel economy. I have an 05 crew cab with the 6.0 and i have gotten up to 20mpg going 60 on the highway, get around 15 doing 75 thouhg.
  3. Proscapez LLC

    Proscapez LLC Senior Member
    Messages: 293

    I dont have a cover but I have drop the tailgate and havent notice a change.
    According to DIC the only way to get near 18mpg is running about 40mph.
    I have check out my fuel mileage the old fashion way, miles divided by gallons
    and DIC was right on the money.
    I was thinking maybe the mass airflow sensor was dirty.
    I replaced the air filter with a Fram Air Hog, It looks just like my other K&N filters.

    I almost bought a 6.0 but I was told they only get 12mpg, So I went with the 5.3.
    Last edited: Nov 26, 2006
  4. Joe D

    Joe D Senior Member
    Messages: 605

    does it have 4.10 gears? To me it seems low for a 1500 with the 5.3, I would expect 16-17 on a steady cruise.
  5. scottL

    scottL PlowSite.com Addict
    Messages: 1,600

    Tail gate down has actually been mis-information. There have been a number of reports saying this causes more back drag than having the gate up. A top or toneu cover offer the best lowering in drag.

    Try the 'ol tune up and check fuel pressure. MAF should not go bad for many years.
  6. victoryrider

    victoryrider Junior Member
    Messages: 22

    They actually tested the theory on the Discovery Channel Mythbusters. They found that without a tonneau you get better gas mileage with the tailgate up. It seems that the air travelling over the cab swirls back down into the bed and go back to the cab vreating a pillow effect the allows air to travel right over the bed. With the tailgate down the pillow effect is gone and the air turbulence is so great that it lowers gas mileage. The difference was not extreme but over several tanks of gas could add up to some savings. With gass prices the way they are now every little bit helps.
  7. Proscapez LLC

    Proscapez LLC Senior Member
    Messages: 293

    I'm not sure of the gear ratio, I'll have to find a RPO code list and figure it out.
    But I don't think it 4.10:1 the engine doesn't rev that high, at 70mph it turning about 2,400rpms.

    Thanks for the info on back drag.
  8. jcesar

    jcesar Senior Member
    from Mi
    Messages: 492

    I have a 96 1/2 ton Sierra with the vortec 350. Get 17 mpg with it.
  9. JeffNY

    JeffNY Senior Member
    Messages: 484

    Yeah, im gunna call chevy, I think somethings wrong with mine too, im getting 11.5mpg with mine.
  10. Jpocket

    Jpocket Senior Member
    Messages: 302

    You've gotta be kidding me on my 05' the BEST i have ever gotten was 11MPG on the highway EMPTY. thats with the 6.0 4.10's AUTO, and 285 tires.
  11. Jpocket

    Jpocket Senior Member
    Messages: 302

    14 MPG is GREAT in my book for any pick up with a V8 in it be it a 1500 or not.
  12. exmark1

    exmark1 PlowSite.com Addict
    Messages: 1,320

    I had a 2002 1/2 Ton ext cab, short box with the 5.3 and I got between 16-18 all the time. When it was needed a tune up I got the 14 you are talking about. Try that or bitching at the dealer... hope you get to the bottom of it!
  13. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    I get 13 pretty much all the time in my 2000 2500. 6.0, 4.10 gears and 265's. Not sure if the prior owner adjusted the speedo for the bigger tires or not.

    14 is pretty bad in a stock 5.3...a guy at work gets consistent 16mpg in a 2003 GM 1500 ecsb stepside. Try reducing your speed to 60-65 and doing basic tuneup stuff. Check your tire pressure, alignment, etc.. Are you running the stock tire size? Knobby tires? Heavy aftermarket wheels? If not you may be trowing your speedo and odo off, which could be messing up your mpg.
    Last edited: Nov 26, 2006
  14. Proscapez LLC

    Proscapez LLC Senior Member
    Messages: 293

    I have under 30k miles on it, I wouldn't think it would need plugs already.

    I have the 3.73 and the G80
  15. Bad Luck

    Bad Luck Senior Member
    Messages: 741

    Same Truck: 04 1500 ECSB Z71 5.3 Auto Trans. I have 3.73's.

    I'm pulling 19-21mpg hwy daily out of my truck. I had a tonneu on the back and took it off. I'm actually getting better mileage WITHOUT it. I set my cruise at 60-62 mph. Oh, and I have 285's at all four corners. Around town it sucks. About 15-17.
  16. Rcgm

    Rcgm Senior Member
    Messages: 613

    I have the same truck thats about what I get in gas mileage.Have your u joints went out yet?Any problems with your speedo cable making noises?Tranny slipping?LOL those are a few problems I have had.Hope you have better luck than me.

  17. Proscapez LLC

    Proscapez LLC Senior Member
    Messages: 293

    I have a clunk noise in the back, when I take off.
    I thought it was a bad u-joint dealer say's, it's normal and u-joint are great and rear lash is good as well no broken gears.
  18. Bad Luck

    Bad Luck Senior Member
    Messages: 741

    You may need to grease the splines on your yoke. (No, seriously). I had the same issue a while back. If you drop your driveshaft and gease the splines on the output shafts the clunk/knock/wierd sound when you hit the gas from a dead stop should go away. A lot of dealers solved this by adding nickel plated yokes, I greased mine at 30k and it hasn't come back yet.
  19. Bowlerdude

    Bowlerdude Junior Member
    Messages: 24


    Question do you ever watch Mythbusters or have you ever heard of it?

    They tackle and investigate Myths or claims of one method, or procedures over others.

    On to the point, Mythbusters DID Tackle the myth about Gas Mileage for Trucks with the tailgate up or down. According to Mythbusters Trucks get better fuel economy with the Tailgate up and or fully installed. The reason is with the tailgate in the up position it creates a Vortex of Air just behind the cab that forces the rest of the air and its inherent drag ABOVE the Rear Bed and Tailgate of the truck decreasing its coefficient of Drag and NOT INCREASING IT, and NOT causing LESS fuel economy with the Tailgate in its up position.

    Don't believe me, or you think that the science is flawed, investigate for yourself. According to Mythbusters there is about a .3 mile to the gallon advantage to leaving your Tailgate in its installed UP position. I know the difference is not alot but my point is that you can't assume one method is better than another method without some degree of testing. Without any data one would assume the Tailgate is creating more drag, but by its location it allows the creation of a vortex that stops drag, GO FIGURE!!

    Last edited: Nov 27, 2006
  20. Rcgm

    Rcgm Senior Member
    Messages: 613

    Hey Badluck

    What do you think this is?SOmetimes I am sitting at a stop light I push the gas the truck sits there for about 1 or 2 seconds then I can feel the tranny kinda slip into gear and take off it happens about once a month.Tell me what you think it is.I have taking it in they drive it say can't find no problem Mr. Roller you are free to go.Does anybody elses silverado shift kinda rough?