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Thread: "New" car getting poor fuel economy. Help

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    "New" car getting poor fuel economy. Help

    I was a sheep, and went and bought a 1999 Honda Accord. I made this choice mainly, because it was a mid-size 4 cylinder, that got good fuel economy ratings.

    Rated at 20 city and 28 highway, I'm currently averaging about 19 mpg...
    I'm not a terribly aggressive driver, there's no leaks or anything(As far as I can tell)... The only thing I can think of that might be hurting fuel economy is the wheels that the prior owner put on. They're 16-inch rims, while the factory rims were 15" in diameter. I never thought when buying the car, that a 1-inch increase would hurt fuel efficiency so much.


    Does anybody know what could be causing this dismal fuel economy?

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    Senior Member Mithrandir's Avatar
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    It might be the larger wheels. If the diameter of the new tires is different than the factory original, the the odometer could lose some accuracy.

    http://wiki.answers.com/Q/Does_rim_o...change_mileage

    Tire size calculator.


    Quote Originally Posted by Brandonjin View Post
    I was a sheep, and went and bought a 1999 Honda Accord. I made this choice mainly, because it was a mid-size 4 cylinder, that got good fuel economy ratings.

    Rated at 20 city and 28 highway, I'm currently averaging about 19 mpg...
    I'm not a terribly aggressive driver, there's no leaks or anything(As far as I can tell)... The only thing I can think of that might be hurting fuel economy is the wheels that the prior owner put on. They're 16-inch rims, while the factory rims were 15" in diameter. I never thought when buying the car, that a 1-inch increase would hurt fuel efficiency so much.


    Does anybody know what could be causing this dismal fuel economy?
    Sincerely,
    Anthony

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    What nobler employment, or more valuable to the state, than that of the man who instructs the rising generation? Cicero (106BC-43BC)

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    Quote Originally Posted by Mithrandir View Post
    It might be the larger wheels. If the diameter of the new tires is different than the factory original, the the odometer could lose some accuracy.

    http://wiki.answers.com/Q/Does_rim_o...change_mileage

    Tire size calculator.
    Thanks for the link, it helped.

  4. #4
    Senior Member grouch's Avatar
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    Quote Originally Posted by Brandonjin View Post
    I was a sheep, and went and bought a 1999 Honda Accord. I made this choice mainly, because it was a mid-size 4 cylinder, that got good fuel economy ratings.

    Rated at 20 city and 28 highway, I'm currently averaging about 19 mpg...
    I'm not a terribly aggressive driver, there's no leaks or anything(As far as I can tell)... The only thing I can think of that might be hurting fuel economy is the wheels that the prior owner put on. They're 16-inch rims, while the factory rims were 15" in diameter. I never thought when buying the car, that a 1-inch increase would hurt fuel efficiency so much.


    Does anybody know what could be causing this dismal fuel economy?

    First off, the EPA ratings were on a dynomometer under laboratory conditions. That said, there's a lot of basic maintenance that, if it hasn't been done, will slurp fuel like a politician at the money trough.

    Since the previous owner put bigger rims, I'll bet he did a bunch of other stuff to it too. Kids often put a cooler thermostat in their engines. On carbureted engines this makes for a denser fuel/air charge. On fuel injected engines like yours, the computer never gets out of the "open loop" warm up mode and keeps injecting extra fuel into the cylinders.

    While you're doing that, change out the air filter. I just bought a car and you could have grown potatos in the filter. Worn spark plugs also can eat gas.

    How are your tires wearing? If they are worn on one side on the front, your wheels need alignment.

    Put a new filter in it and change the thermostat and coolant. I do that on everything I buy. That way I know they are good.
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    Ridin Dirty dom's Avatar
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    How many miles on it. Have you kept up with the factory scheduled maintenance?

    Everything mentioned above for sure.

    AND

    Just tossing this out there: fuel filter, air filter, plugs, wires, proper air pressure in tires..

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    Quote Originally Posted by grouch View Post
    First off, the EPA ratings were on a dynomometer under laboratory conditions. That said, there's a lot of basic maintenance that, if it hasn't been done, will slurp fuel like a politician at the money trough.

    Since the previous owner put bigger rims, I'll bet he did a bunch of other stuff to it too. Kids often put a cooler thermostat in their engines. On carbureted engines this makes for a denser fuel/air charge. On fuel injected engines like yours, the computer never gets out of the "open loop" warm up mode and keeps injecting extra fuel into the cylinders.

    While you're doing that, change out the air filter. I just bought a car and you could have grown potatos in the filter. Worn spark plugs also can eat gas.

    How are your tires wearing? If they are worn on one side on the front, your wheels need alignment.

    Put a new filter in it and change the thermostat and coolant. I do that on everything I buy. That way I know they are good.
    Basic maintenence was done the weekend I bought the car, about three months ago. Spark plugs changed, air filter, coolant, oil. Vehicle's wheels are aligned and not wearing in any unusual way.

    Where would this thermostat be?

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    Quote Originally Posted by dom View Post
    How many miles on it. Have you kept up with the factory scheduled maintenance?

    Everything mentioned above for sure.

    AND

    Just tossing this out there: fuel filter, air filter, plugs, wires, proper air pressure in tires..
    105,000 miles are on the car. I havent really checked the psi of the tires but they are all firm.
    The only thing that may not have been done is the fuel filter. I have no idea where that is, and I can't recall if we got it done.


    I think the gas guage may just be inaccurate. The car has a 17 gallon fuel tank, and I always fill up when 3/4 of the gas is gone, and I can usually only put 11-12 gallons in it.

    Reguardless, thanks for the replys everyone.

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    Administrator Ken's Avatar
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    Quote Originally Posted by Brandonjin View Post
    I was a sheep, and went and bought a 1999 Honda Accord. I made this choice mainly, because it was a mid-size 4 cylinder, that got good fuel economy ratings.

    Rated at 20 city and 28 highway, I'm currently averaging about 19 mpg...
    I'm not a terribly aggressive driver, there's no leaks or anything(As far as I can tell)... The only thing I can think of that might be hurting fuel economy is the wheels that the prior owner put on. They're 16-inch rims, while the factory rims were 15" in diameter. I never thought when buying the car, that a 1-inch increase would hurt fuel efficiency so much.


    Does anybody know what could be causing this dismal fuel economy?
    If the majority of your driving is around town, short journeys and a fair amount of stop-start motoring then the consumption you are getting is probably not unreasonable.

    My Carina gives me around 37/39 mpg UK on long runs but this drops to around 29 mpg around town. If I just use the car for short trips (two or three miles) local journeys only this can drop down to around 24 mpg as the car is in the 'richer mixture' warming up cycle for most of the journey. Toyota claims for my car are - Urban cycle - 30.7 mpg UK. Steady 56 mph - 57.6 mpg UK. Steady 75 mph - 42.8 mpg UK. I have never achieved the quoted figures nor would I expect to, except on a rolling road where there is no wind resistance to factor in.

    Ken.
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    Quote Originally Posted by Ken View Post
    If the majority of your driving is around town, short journeys and a fair amount of stop-start motoring then the consumption you are getting is probably not unreasonable.

    My Carina gives me around 37/39 mpg UK on long runs but this drops to around 29 mpg around town. If I just use the car for short trips (two or three miles) local journeys only this can drop down to around 24 mpg as the car is in the 'richer mixture' warming up cycle for most of the journey. Toyota claims for my car are - Urban cycle - 30.7 mpg UK. Steady 56 mph - 57.6 mpg UK. Steady 75 mph - 42.8 mpg UK. I have never achieved the quoted figures nor would I expect to, except on a rolling road where there is no wind resistance to factor in.

    Ken.
    I understand, thanks for the comment.
    I guess I'm just disappointed. The car I drove before I bought this, was a 1998 Toyota Camry. It was a year older, had 70,000 more miles, and had 2 more cylinders. It was rated at 17/25, but I got around 22 average. Same driving. My daily commute hasn't changed between the two cars.

    I thought that there might be something really wrong with the Accord, getting a 19mpg average. I feel like I literally just threw away my money. Now I have a gas guzzler, and its slow. Lesson learned.

  10. #10
    Administrator Ken's Avatar
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    Quote Originally Posted by Brandonjin View Post
    105,000 miles are on the car. I havent really checked the psi of the tires but they are all firm.
    The only thing that may not have been done is the fuel filter. I have no idea where that is, and I can't recall if we got it done.


    I think the gas guage may just be inaccurate. The car has a 17 gallon fuel tank, and I always fill up when 3/4 of the gas is gone, and I can usually only put 11-12 gallons in it.

    Reguardless, thanks for the replys everyone.
    Apart from the tire pressures, which can add a lot of drag if the pressures are too low, I would suggest you jack the car up and check each wheel for brake drag which can also have a big effect on gas mileage. If any of the caliper pistons are sticking they can add a fair amount of drag as can maladjusted rear brakes if they are of the drum type.

    I have yet to own a car where the gas gauge is truly accurate. If I work out my mileage from the gauge the first half tank gives me about 60 mpg but as soon as it get below half full I get about 25 mpg. I have a programme on my computer that, when I enter miles since last fill up, gas cost per litre, and amount paid calculates 'Number of litres, miles per litre, cost per gallon, number of gallons, miles per gallon, (our gas comes in litres), and petrol cost per mile.' It enables me to keep quick track despite all the fluctuations of gas prices.

    Adding a couple of psi to my car tire pressures makes a couple of mpg improvement, at the expense of a slightly harsher ride. Always remember, by the way, to add two or three psi to your car tire pressures if proposing a long fast run. On a 'bike, of course, drop the pressures by a couple of pounds - if going on track get the tire manufacturers recommendations, my Honds runs 36 front 42 rear on the road but starts at 34 front 32 rear on the track with a two lap warm up before starting to push lap times.

    Ken.
    Die dulci fruimini!
    Ken.
    Wolds Bikers, Lincolnshire, England.

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    Quote Originally Posted by Ken View Post
    Apart from the tire pressures, which can add a lot of drag if the pressures are too low, I would suggest you jack the car up and check each wheel for brake drag which can also have a big effect on gas mileage. If any of the caliper pistons are sticking they can add a fair amount of drag as can maladjusted rear brakes if they are of the drum type.

    I have yet to own a car where the gas gauge is truly accurate. If I work out my mileage from the gauge the first half tank gives me about 60 mpg but as soon as it get below half full I get about 25 mpg. I have a programme on my computer that, when I enter miles since last fill up, gas cost per litre, and amount paid calculates 'Number of litres, miles per litre, cost per gallon, number of gallons, miles per gallon, (our gas comes in litres), and petrol cost per mile.' It enables me to keep quick track despite all the fluctuations of gas prices.

    Adding a couple of psi to my car tire pressures makes a couple of mpg improvement, at the expense of a slightly harsher ride. Always remember, by the way, to add two or three psi to your car tire pressures if proposing a long fast run. On a 'bike, of course, drop the pressures by a couple of pounds - if going on track get the tire manufacturers recommendations, my Honds runs 36 front 42 rear on the road but starts at 34 front 32 rear on the track with a two lap warm up before starting to push lap times.

    Ken.
    I thought I replied to this yesterday.

    What program are you using? I just made a fuelly account which seems like a similar service. My brakes are all discs, but I'll check them anyway.

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    Administrator Ken's Avatar
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    Quote Originally Posted by Brandonjin View Post
    I thought I replied to this yesterday.

    What program are you using? I just made a fuelly account which seems like a similar service. My brakes are all discs, but I'll check them anyway.
    The programme I use is one I wrote using Excel. It is just a case of entering fairly simple formulae into the appropriate cell then, at each gas purchase, filling in the date, total cost, and cost per liter or gallon. Excel does the calculations and fills in all the answers. Probably does a bit more than 'Fuelly' but that is just to do the extra conversions to relate to gallons rather than liters.

    Disc brakes can suffer from sticking/jammed pistons, usually nothing that a good clean won't cure. Just remove the pads, pump out the pistons a trifle, use a wooden pad to stop the piston coming right out, clean thoroughly with brake cleaner, push the pistons back and refit the pads. Pump the brakes a few times to make sure that the pads are back in position. Really bad cases of piston corrosion and siezure may require replacement piston and seal sets with a worst case scenario of replacement caliper assemblies.

    Ken.
    Die dulci fruimini!
    Ken.
    Wolds Bikers, Lincolnshire, England.

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