Crazy gas mileage drop off

Discussion in 'Engine & Performance' started by D A, Jan 10, 2017.

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  1. D A

    D A Junior Member

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    2013 Ram Laramie 4x4 8 speed 60K miles all stock, most options. Up until my 60K service and tire change a month ago, I easily registered 17-19mpg in town and 19-22 highway (even in 4wd auto). Since then, I've done a 400 mile rt to Houston and at best registered 14-15 mpg. What do I need to check first to fix this? I know the mileage monitors in these trucks are off a bit but still a 5-6 mpg drop seems pretty drastic. Is there a diagnostic to check things out? Any thoughts appreciated. I love this (my first) truck, but now??
    Don
     
  2. Hemi450hp

    Hemi450hp Moe's Performance

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    Cooler air is denser air, which will use more fuel...this is why it is very normal to see a drop in mileage during the cooler winter months. Also, did you go back with the exact same tire, or a different brand/size?
     
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  3. CDNUSER

    CDNUSER Senior Member

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    I also had a big drop when the colder temps rolled in. Also with a change of tires.
    I went from 13.1 L/100kms to 18.5 L/100kms avg.


    Sent from my iPhone using Tapatalk
     
  4. D A

    D A Junior Member

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    I stayed with stock tire size but firestone mild offroad. Didn't think that would cause a drastic change. Also does the colder weather impact the mileage that much? This is my third winter but first mileage drop off. thanks.
     
  5. MADDOG

    MADDOG Super Moderator Staff Member

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    I suspect they may have introduced winter blend fuels in your area recently?

    My mileage always goes down in winter as the ethanol blends are brought into the fueling stations.

    However, you said you have no codes so that's good. I'd suggest pulling the air intake tube and make sure your throttle body isn't all gunked up. Also, now would be the time to change out the EGR valve.

    Lastly, give the fuel system a good cleaning with an in-tank fuel additive and possibly do the top end with Seafoam or other intake / engine top end cleaner.

    When was the last time you changed your plugs?
     
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  6. KingTuna

    KingTuna Senior Member

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    2013 hemis are supposed to have the plugs changed at 30K right? Have you changed the plugs yet?
     
  7. D A

    D A Junior Member

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    Just had a 60K dealer service where they said they cleaned the fuel system and changed plugs again, the bill reflects this. Not too keen on these local dealer service depts. Hopefully, they didn't cause the problem as now that you mention it, I don't think I noticed the issue til about a month after this service. I would think checking the egr should have been included. Thanks.
     

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