Fuel consumption - 2005 Tucson

Discussion in 'Hyundai Tucson' started by Judith Raskin, Apr 9, 2006.

  1. I have a Tucson, 2005, automatic, 4WD, 6 cyl. Though I got a good deal when
    I stumbled on a used one (3300 miles) and bought it at a good price. But
    mileage has been awful. I've put 2000 miles on it so far, and mpg has
    dropped off from 13 mpg to current 10 mpg... I had only one lengthy freeway
    run, about 200 miles, and even then only did about 17 mpg.

    Does anyone have any thoughts? I took it to dealer; mechanic says there is
    nothing wrong with car, but I disagree. I don't know how to approach this
    problem mechanically.

    Judith Raskin, Apr 9, 2006
    1. Advertisements

  2. Judith Raskin

    hyundaitech Guest

    Chances are, the technician's right. The technician has the capability to
    see the computer's data stream and make sure everything appears correct.

    As to what you can do:

    Drive the vehicle easily. If your in an urban area, this will be

    Make sure the vehicle engages all 4 forward gears and that the engine
    seems to run well.
    hyundaitech, Apr 10, 2006
    1. Advertisements

  3. Chances are, the technician is wrong. Just because he or she can read
    the data doesn't guarantee the data is correct.

    Your Tucson has an EPA rating of 17mpg city/22mpg highway. Real world
    mileage is always a little less. But not 10 mpg. Carefully measure your
    gas usage and odometer readings. If you really are getting only 10 mpg,
    then there is something wrong. Me, I'd pull a spark plug or two to see
    if its running rich -- maybe the onboard chip has got the air/fuel mix
    wrong, or a fuel injector is bad, or ... you get the idea.

    For the tech to read the data and shrug his or her shoulders and say
    nothing is wrong is being a little lazy, IMHO.
    Folsom Inmate, Apr 11, 2006
  4. Thanks, that's how I feel. The Hyundai tech may be treating this somewhat
    cavalierly. I will have to go back to the shop. I do treat my car well,
    although it is used mostly in city driving. But I don't have either a heavy
    or a light foot on the pedal. I know how to drive.

    Judith Raskin, Apr 11, 2006
  5. Judith Raskin

    hyundaitech Guest

    Folsom said:

    Me, I'd pull a spark plug or two to see
    if its running rich -- maybe the onboard chip has got the air/fuel mix
    wrong, or a fuel injector is bad, or ... you get the idea.

    For the tech to read the data and shrug his or her shoulders and say
    nothing is wrong is being a little lazy, IMHO.

    I think you fail to understand what the technician can see and interpret.

    A good technician can drive the vehicle and tell whether it has the proper
    amount of power, whether the transmission or clutch is slipping, and
    whether the transmission shifts through all the gears properly.

    A good technician can look at the data stream and see whether the vehicle
    is running rich; he doesn't need to pull a spark plug to do that. In the
    data stream, the technician will see values for the oxygen sensor readings
    and the fuel trims. The oxygen sensors, combined with the programming of
    the engine control module, control the fuel mixture. So, to determine if
    the vehicle is controlling the mixture properly, the technician looks to
    see if the front oxygen sensors cycle properly. The technician looks at
    the fuel trims to see that the computer isn't unexpectedly providing
    significantly more or less fuel than expected for the given operating

    Excessively large fuel trims (in either direction) indicate problems with
    oxygen sensors, unexpected air or fuel leakage into the intake/combustion
    chamber, or possibly other problems.

    And this isn't the limit of the data the technician can see. A good
    technician doesn't just read the data; he interprets the data to see
    whether it appears correct. So, no it's not lazy. It's the technician
    performing a task to approach a problem in a logical and efficient manner.
    Suppose you were footing the bill? Would you want to continue paying the
    technician to pull stuff apart until he found something? How much would
    you spend without the technician finding anything before you were willing
    to give up? Would your engine be in pieces on the floor? The reality is
    that checking the data stream, combined with a test drive, *is* an
    effective way to determine whether a vehicle is running properly.

    I give some kudos to this customer. She actually knows her fuel economy.
    Most of the customers who complain about their fuel economy have no idea
    what it is and many are confused about how to compute it. It's sad,
    really. And I agree this poster's fuel economy is low enough to give some
    pause. But I know neither the customer's driving style nor driving
    conditions. It's enough that I'd look pretty hard at all the data. I'd
    also want some more information regarding what is involved in a typical
    daily trip for this customer-- especially if I found nothing wrong. Does
    she warm the vehicle prior to starting a trip? How short are the trips?
    In what sort of traffic are the trips taken?

    Just like any other problem, this one needs to be aproached logically in
    order to find a resolution.
    hyundaitech, Apr 11, 2006
  6. My 2002 Sante Fe was getting 13 mpg City. Turned out to be BP
    gasoline! I switched to Marathon or Shell & get 22 City/ 30 Hwy & its
    an automatic! SO good gas at 97 octane since high test isn't needed

    I was also told by my tech never to fill up in the rain, and to run it
    down to 1/8 of a tank to fill & that gives me correct mileage which 1/4
    tank doesn't. So try all of this & let us know.
    The Awesome 1, Apr 12, 2006
  7. Judith Raskin

    bo peep Guest

    <<Does anyone have any thoughts?>>

    Try driving on level ground, at a steady speed, where there is no other
    traffic around. Take foot off gas, shift to neutral, and observe how
    quickly the vehicle slows down. If it slows too quickly, something may
    be dragging (i.e. brakes) or out of alignment (i.e. wheels).

    John Cowart
    bo peep, Apr 12, 2006
  8. Judith Raskin

    bo peep Guest

    <<Does anyone have any thoughts?>>

    Are you one of those people who "rides" the brakes? Just wondering...

    John Cowart
    bo peep, Apr 12, 2006
  9. Judith Raskin

    Matt Whiting Guest

    Well, 97 octane is pretty high test if you ask me. Where I live 87 is
    typical and 94 is about as high as you can find short of aviation or
    racing fuel.

    What is your tech smoking? Filling up in the rain? Not getting correct
    mileage at 1/8 tank vs. 1/4? What a bunch of hogwash. You won't get
    correct mileage just checking one tank in any event. You need to check
    at least five in a row to have any assurance of a reasonable average.
    And if you check several in sequence, it doesn't matter if you fill up
    at 1/8, 1/4 or 1/2 level. Any little over or underage on one tank will
    be factored out by the next tank.

    Matt Whiting, Apr 12, 2006
  10. Judith Raskin

    hyundaitech Guest

    Scientifically speaking, the more fuel used, the less error will be
    introduced by filling variances. I.e.-- there's a significantly larger
    amount of fuel used than the difference in how full the tank is based on
    differences in auto shutoff, vehicle slope, and other factors.

    But you're correct on taking several samples, regardless of amount of fuel
    at fill-up. This will minimize error as well as make aberrant values stand
    hyundaitech, Apr 12, 2006
  11. Judith Raskin

    hyundaitech Guest

    Nice points, John. I usually check for brakes dragging by coasting to a
    stop in neutral on a slight upward incline. The vehicle should smoothly
    reach a stop and begin rolling backward-- it should not jerk when the stop
    is reached.

    The chances of getting a shop to put the vehicle on the front end rack to
    check alignment (without ponying up at least an authorization for the
    typical alignment charges) are small. Hyundai won't pay for the alignment
    if the values are within spec, so the dealer will be looking to charge the
    customer for their effort if there's no problem. Look for front or rear
    tires wearing on either the inside edges or outside edges and make sure
    the steering wheel is centered. Either the wear or the steering wheel
    issue indicate a likely alignment problem, but absence of these issues
    (especially on a new vehicle where tire age is minimal) doesn't mean there
    isn't a problem with the alignment.
    hyundaitech, Apr 12, 2006
  12. Judith Raskin

    Matt Whiting Guest

    True, if you are only checking that one tank. However, checking one
    tank isn't statistically significant to begin with so making an
    untrustworthy number just slightly less untrustworthy isn't really

    And when you do this, don't calculate each tank separately and then
    average them as that isn't legitimate either. Add up the total gallons
    consumed and divide that into the total miles traveled across all tanks,
    being sure that your first mileage point was a full tank. Do this for
    five or more consecutive fill-ups and you will get a reasonable estimate
    for average fuel economy during that time.

    Matt Whiting, Apr 13, 2006
  13. No, I don't. I try to get up to speed as quickly as practical, given what
    traffic is doing. About 80% of my driving is in the city, where the limit
    is usually 35 mph, the rest on the freeway. My previous vehicles delivered
    EPA or better until they were very old. I am not the type to jump out at
    red lights or try to beat the light; it's a waste of time. I am plain
    disappointed that this car is not deliverying mileage anywhere near the EPA

    Judith Raskin, Apr 15, 2006
  14. After reading more of the thread I still think there's something wrong
    for you to get 10 mpg.

    As I mentioned in my prior post, I'd check the spark plugs. The tech
    says the computer says everything is OK. A visual inspection of the
    plugs is an independent check. The plugs tell you if the engine is
    getting too much fuel. See


    If the plugs look like the first case, then that verifies the engine is
    getting the proper amount of fuel. If they look like the second case
    then you know the fuel system has a problem and the tech's computer data
    is wrong.

    If the plugs look normal, then maybe a brake is dragging -- such as
    caused by the stability control recall. 2005 models have a problem with
    their stability control, causing engine power loss and a brake to drag.
    Is yours a 2005 and has the recall been serviced?

    I'd keep after the service manager. In this era of $3 gas, there's no
    reason to accept 10 mpg. Good luck!
    Folsom Inmate, Apr 15, 2006
  15. Thank you again, I will go to that website. As for a stability control
    recall, I have not heard a word. One of the first things I did when I got
    this car is registered online with Hyundai; I figured it was a way to get
    word on such things quickly. But I have never had a message of any kind.
    Mail, email, smoke signals or semaphore!

    Judy Raskin
    Judith Raskin, Apr 16, 2006
  16. Judith Raskin

    hyundaitech Guest

    There are two recalls to reprogram the Stability Control (ESP) on 2005
    Tucsons. The first is only for vehicles produced prior to 2/27/05 and
    reduces system sensitivity. (Unofficially, I've heard that it could
    activate at speeds of a few miles an hour, but I have no verification of
    this.) The second applies to all 2005 Tucsons and makes the ESP more
    active during "extreme driving conditions." It's possible the dealer
    performed either or both recalls before you received the notice and you
    weren't aware they did it. But I expect zero correlation with fuel
    economy. In the first case, we're talking about infrequent erroneous
    application at very low speeds, and in the second, we're talking about
    conditions under which you're not likely to be driving the vehicle.

    If you'd like to post your VIN, I'll run it and check for recalls.
    hyundaitech, Apr 17, 2006
  17. I am willing to give you my VIN number, but not in this public forum. If
    you will give me an email address, I will send it to you privately. Thank
    you for checking this for me. -- Judy
    Judith Raskin, Apr 17, 2006
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.