Slight drop in mpg
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Thread: Slight drop in mpg

  1. #1
    Nooblets Polaris's Avatar
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    Slight drop in mpg

    So after a year of attempting to rid the check engine light off my moms 01 nissan quest, it finally went away!
    Just to give you an idea of how irritating it was, i had a nightmare that it came back!
    The final nail for the coffin was providing ground directly from the battery to the intake manifold.
    Well now i have another problem, there's a slight-but-strong miss at idle, when i mash the pedal i dont get any kind of jolt whether im at 20,50 or 70 mph. Also my Long term fuel trim is -10%. Im running rich right? Well my mpgs dropped from 18 to 15.
    Its a little bit but im curious to see what you guys think would cause my trims to be negative.
    More info.
    Ive changed spark plugs,in line fuel filter, added a fuel cleaner, AT fluid, both o2 sensors, distributor, spark plug wires, vacuum lines, pcv valve, throttle sensor, mass air flow sensor.
    Vacuum shows 20 or 21 inches of mercury
    Have not tested fuel pressure, fuel pump and strainer have never been changed so thats what im thinking.( it does take a second or 2 of cranking before it starts up)
    Air filter looks clean
    No Check Engine Light but i do have a pending knock sensor code.
    Just throwing this out there 🙂 Thanks!

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  3. #2
    Truck? What truck?! scottyrocks's Avatar
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    Are you asking in regard to your mom's Nissan?
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  4. #3
    Platinum Member fear24's Avatar
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    i'm presuming he's asking about the quest....as the mileage dropped from 18-15. if a civic got that bad of mileage on a consistent basis....it wouldn't be a civic!

    my parents had a LW300 V6. they towed it behind motorhome. anyways...i borrowed it and noticed after a round trip to work (54 miles)i had used almost a 1/2 tank of gas. it seemed to run fine. upon further testing, found out 3 of the coils went bad (out of 6). replaced them, and the mileage returned to what it was.
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  5. #4
    Nooblets Polaris's Avatar
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    Quote Originally Posted by fear24 View Post
    i'm presuming he's asking about the quest....as the mileage dropped from 18-15. if a civic got that bad of mileage on a consistent basis....it wouldn't be a civic!

    my parents had a LW300 V6. they towed it behind motorhome. anyways...i borrowed it and noticed after a round trip to work (54 miles)i had used almost a 1/2 tank of gas. it seemed to run fine. upon further testing, found out 3 of the coils went bad (out of 6). replaced them, and the mileage returned to what it was.
    Correct this is about the Quest. It does have a miss as if it were an ignition coil but this engine has its coil built into the distributor, which is new. Im thinking of switching to iridium plugs to see what good that does.

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