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Thread: 2005 sts 3.6 reasons for poor MPG?

  1. #1
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    2005 sts 3.6 reasons for poor MPG?

    I bought a sts 3.6 2005 w 77k miles and it averages 13.7 mpg and engine light is not on I had a previous one and it averaged 22.7. Can somebody please give me tips.


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  3. #2
    1BadCadSTS's Avatar
    1BadCadSTS is offline Cadillac Owners Connoisseur
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    Awd? Normal. He probably reset it and drive it on the highway before you bought it to inflate the number. Cold weather also nets lower mpg.

  4. #3
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    Rwd and I drove it home on highway from El Paso to las cruces. What could be other reasons for poor mileage? Fuel filter maybe spark plugs or something I can change make it better.

  5. #4
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    Re: 2005 sts 3.6 reasons for poor MPG?

    Both could cause it but if it doesnt stumble unlikely

    any CEL? are your brakes possibly hanging up?

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    What is CEL and what is hanging up mean?sorry just trying to learn

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    Re: 2005 sts 3.6 reasons for poor MPG?

    CEL = Check Engine Light

    Hanging up = brakes sticking / staying applied even when not on the brakes

    Bad tire pressure? (really low pressure)
    Terrible head wind?
    Not shifting into the highest gears when it can?
    Towing something?
    Hauling more weight than the car allows?

  8. #7
    EChas3's Avatar
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    Re: 2005 sts 3.6 reasons for poor MPG?

    ...Lead Foot...

    No seriously, few of these cars were optimized for mileage.

  9. #8
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    Cel is not on and and I bought the car w all tire being same width as the front. They are 35 wide in front and has same on back, the car calls for 55 on the back. I don't think brakes are hanging.could it be the tires?

    ----------

    What's lead foot? I wanna rule out small things I can do my self. Any suggestions?

  10. #9
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    Nothing perosnal but based on your responses close the hood and take the car to the dealer. For all our safety do not attempt to repair on your own.

  11. #10
    Ludacrisvp's Avatar
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    Re: 2005 sts 3.6 reasons for poor MPG?

    Quote Originally Posted by 3.6sts View Post
    Cel is not on and and I bought the car w all tire being same width as the front. They are 35 wide in front and has same on back, the car calls for 55 on the back. I don't think brakes are hanging.could it be the tires?

    ----------

    What's lead foot? I wanna rule out small things I can do my self. Any suggestions?
    If anything the narrower set of tires on all 4s might have slightly improved milage but so little you would not notice most likely.

    Lead Foot ... not sure if you are being serious here or just have never heard that before.
    Lead Foot = you are always flooring the gas every time you touch it... accelerating as fast as possible as often as possible.
    Typically also means you are slamming on the brakes too at every light.

  12. #11
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    Oh I don't always floor it. I just want to the possibilities of why it's so poor

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    Would it mattered if I used platinum plugs it calls for over iridium

  13. #12
    1BadCadSTS's Avatar
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    Re: 2005 sts 3.6 reasons for poor MPG?

    OEM delco or denso ONLY

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    Is there a difference? And what would happen if gap is to wide or to close

  15. #14
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    Re: 2005 sts 3.6 reasons for poor MPG?

    yes

    and dont

  16. #15
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    So I can use the above named brands but I'm asking if I can use iridium or do I have to use the platinums?

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