2012 DD15 fuel mileage

Discussion in 'Freightliner Forum' started by Prairefarmer, Jan 19, 2020.

  1. Prairefarmer

    Prairefarmer Bobtail Member

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    Jan 19, 2020
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    Hey guys. I’ve been on here quite a bit lately and read a lot about my problem already, just wondering if there’s any other in site.
    I recently bought a 2012 Cascadia with DD15. Problem is it’s only getting about 3.75 MPG, average between loaded and empty miles which are 50/50 split. Here’s the specs.
    -46,000 rears
    -22.5 tires
    -3.91 gears
    -Eaton 18 speed
    -550hp DD15
    -46,500kg loads
    It has been -40 Celsius here for the past week which is as long as I’ve ran the truck.
    It has been doing the “rak rak rak” while
    Idling so I’ve purchased a new fuel quantity valve. Do you think this will help the fuel mileage? Anything else I can try? Or is this just normal? TIA
     
  2. Crude Truckin'

    Crude Truckin' Road Train Member

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    You idle overnight? I'm assuming you are at those temps. Crappy fuel, moderately heavy loads, cold, bad mpg.
     
  3. Prairefarmer

    Prairefarmer Bobtail Member

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    Jan 19, 2020
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    I did idle a couple of nights. But those MPG were based off of running time only. Doing a load of 2 consecutive loads and filling up and figuring it out! Fuel is no different than any of the other guys I work with.
     
  4. Hammer166

    Hammer166 Crusty Information Officer

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    ~8600+' and loving it!
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    That's what, 94,000#, and those short rears, plus blended fuel @ that temp ? What kind of mileage were you expecting?

    But besides that, I'd check for boost leaks on that age truck. That will kill fuel mileage.
     
  5. Prairefarmer

    Prairefarmer Bobtail Member

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    Jan 19, 2020
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    Better than 3.75... I’m not looking to go broke. Guys I’m running with on the exact same run burn upwards of 200L less in fuel per day. Same spec trucks. Yes I know there’s 1000’s of differences and things that can cause crappy mileage. Just was looking for maybe something obvious I should be checking. I will get the trucks boost system checked for leaks on next days off! Thanks
     
    Hammer166 Thanks this.
  6. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    Get that QCV changed. That will help for sure.
     
  7. Working2party

    Working2party Medium Load Member

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    You might be able to save alittle more letting your engine “dig alittle deeper” in your torque range. As the trucks get newer the power/ efficiency rpm band gets lower.

    Other than that start with the basics. Check/replace fuel&air filters, check for lost boost (leaks). If all checks out get a good overhead run on it.

    The overhead is the one thing left that a mechanic still has to have “a surgical” feel for.
     
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