low gas mileage after ignition coil replacement

Lincoln LS

  1. 5spdLS

    5spdLS LVC Member

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    I have not seen a thread exactly like this, so forgive me if it's been talked about.

    I always keep gas mileage totals when I fill up and this last summer I was averaging 19/21 in the city, stop and go driving, and 25 on the interstate with cruise control.

    4 months ago I had an ignition coil replaced and since then my gas mileage has plummeted. When I was driving around on the bad coil I was getting just slightly worse than normal gas mileage, perhaps 1-2 mpg less.

    After the repair I started noticing I was only getting 20 on the interstate, then I took some in town measurements and I was getting 180 to a tank (that's 10 MPG). I let my car warm up for 30 seconds, don't drive fast/accelerate hard, and I have a V6 with the 5 speed.

    The last tuneup was about a year ago. I also find it odd because this summer I had the AC on all the time, now the AC is not on.

    Any ideas would be appreciated before I take it to Ford so they can stick it to me with their service rates.
     
  2. dilligaf

    dilligaf New LVC Member

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    Is the car running better since the coil replacement? Maybe whoever you had fix it did not hook everything back up correctly.
     
  3. NYC LS8

    NYC LS8 Dedicated LVC Member

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    Try changing the fuel filter? Could be coincidental.
     
  4. 5spdLS

    5spdLS LVC Member

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    I will try the fuel filter, I am not sure if that has ever been replaced and I have 139k on the clock. The car runs normal now. No misfiring (that I can feel or tell) the engine pulls strong like before the coil replacement.
     
  5. GWL

    GWL Dedicated LVC Member

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    One thing we all have to remember about gas mileage is the different fuel blends the EPA forces on us for different seasons. In some areas, the winter blends drop as much as 1.5 mile per gallon compared to summer blends. The last time I checked I believe that in the US we had more than 17 differing blends required for differing areas of the country. On top of that the blends also change year to year. General rule, more ethanol (alcohol) = lower mileage.
     
  6. lseguy

    lseguy Dedicated LVC Member

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    Also its winter. Takes much longer for the engine to reach full operating temperature. And until the engine reaches full operating temps, the efficiency of the engine (MPG) will not be 100%
     
  7. camthman

    camthman Dedicated LVC Member

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    Definitely replace the fuel filter if it has never been done before.
     
  8. 5spdLS

    5spdLS LVC Member

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    Yeah, I thought about that. I would be okay with my gas mileage going down to 17 or so. But it's much worse than that. Today I filled up and put 8.5 gallons in, my trip was 110. That's 13 MPG... I'll see about the fuel filter and report back!
     
  9. xarruda89x

    xarruda89x Dedicated LVC Member

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    I bought my car with an average of 17.9 MPG, with 3-4 bad coils ( might be the reason why the previous owner got rid of it ) and since i got those replaced by Lincoln/Ford, my MPG dropped to 12.8 MPG average, yes it is winter and temps make a difference, but i will also check on that fuel filter as well.
     
  10. d-i-s-t-o-r-t-e-d

    d-i-s-t-o-r-t-e-d Active LVC Member

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    I believe the cold weather is causing the fuel to be more dense causing the motor to burn more fuel. Remember cold air is more dense(basics of science) I know my MPG went from 18 to 16 and it doesn't matter if I reset the mpg counter or drive it like a 80 year old woman it doesn't seem to get any higher.
     
  11. 5spdLS

    5spdLS LVC Member

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    Replaced fuel filter, spark plugs, it's warmer out... and still getting this crappy MPG. Any ideas?
     
  12. pektel

    pektel Dedicated LVC Member

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    Try switching gas stations? Proper air pressure in tires? There's so many things that go into fuel efficiency...
     
  13. 5spdLS

    5spdLS LVC Member

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    Tried different gas stations. ie sticking with BP for a while, then shell... switching it around, etc.

    I constantly make sure my tires are properly inflated.

    I have a clean air filter.
     
  14. 02LincLS

    02LincLS Dedicated LVC Member

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    O2 sensor(s)? no check engine lights? clean MAF sensor? clogged fuel injector? uneven tire wear/ alignment/worn suspension? a sticking brake caliper/ ebrake? new synthetic 5w-20 oil + filter

    how much highway/city driving do you do? when i was doing 80%+ highway driving, i was at 22-23mpg. now i'm probably 40% highway and high 17mpg is all i can muster. stop and go KILLS milage in these.
     
  15. 2000LSMichael

    2000LSMichael Active LVC Member

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    I changed most of the items mentioned above (MAF sensor, coils, spark plugs, all four O2 sensors) and drove it to work (approx 20 miles one way) and it was getting approx. 24. Granted, it was not through a tank of gas or two to get an overall reading, but my LS V-8 runs a lot better that it did. With brand new injectors it runs pretty good.

    I forget what mileage you said, but when I got my LS a few months ago it had 102,000 on it (although I had been around the car for a few years). The new 02 sensors seem to help the mileage.
     

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