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sudden drop in mpg???

Discussion in 'Gen II Prius Fuel Economy' started by fikey13, Dec 6, 2008.

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  1. fikey13

    fikey13 Junior Member

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    sorry. i know this has been addressed before, but not exactly the same. i constantly averaged around 48 mpg in winter and 50-52 mpg in summer for the first 40,000 miles. as it is now cold again, i expected to have a drop in economy, but i am averaging about 44- 45 mpg. i know this is still good, but definitely have had a drop (several tanks). i checked the obvious culprits: tires - ok, brake not on, engine and compartment filters were changed recently, oil is fine....... any ideas? two other issues i was hoping in which someone could "enlighten" me is: what is the "flashing" i read about. does anyone recommend over inflating the tires above the 35/33 psi?
    thanks,
    fikey
  2. morpheusx

    morpheusx Professor Chaos

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    I go on Vacation to Virginia several times a year. I'll inflate to 50 front 48 rear. The roads in VA are so smooth. (at least they are everywhere between Richmond and VA Beach.) Something that you may not have thought of is that you may be due for a tank of Fuel injector cleaner. Go to advance autoparts, autozone, or wal-mart and pick up a bottle of the Chevron w/ techron fuel injector cleaner and dump it in the gas tank. I use this product every about every 10,000 miles and I have always seen an immediate increase.
  3. hobba

    hobba New Member

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    I recently had my fuel injectors cleaned at the dealer. Saw and immediate increase in mileage back to what I got in the beginning. Certainly try the fuel injector cleaner at the parts dealer first......
  4. spitinuri

    spitinuri Member

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    I agree with both Morpheusx and Hobba. Get the fuel injectors clean. There are plenty of folks who run higher tire pressure (myself included). What you need to understand is that when you inflate over recommended tire pressure you give something up (ie. handling, ride, braking, safety). For that reason most would not recommend someone run higher than recommended tire pressure.
  5. diamondlarry

    diamondlarry EPA MPG #'s killer

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    Since you mentioned that you recently had the oil changed, the first thing I would do before anything else, is check to make sure they didn't overfill the oil. It should NOT be above the upper mark on the dipstick. This condition is a known mpg robber.
  6. richard schumacher

    richard schumacher shortbus driver

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    Yes, check the oil level.

    Think twice about inflating above the max pressure given on the side of the tire (44 PSI for the original tires). But going up to that point is inarguably safe and will help MPGs. Note that the ride and handling will change.

    What kinda crappy gas do some people get such that they need injector cleaner? I use Shell E10 and never have any trouble.
  7. JimboK

    JimboK One owner, low mileage

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    Beyond the good advice given by others, consider that Virginia temps have been below normal the last few weeks. Mid-40s for someone with normal driving conditions in our recent weather still is reasonable -- though there is room for substantial improvement.

    Where are you in VA? If you're near Richmond, I don't mind meeting with you to give you an in-person assessment and hands-on clinic.
  8. fikey13

    fikey13 Junior Member

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    thanks for all the advice. i am going to inflate the tires to the max. just for added incentive, i have a friend who retired from the government. while employed by them, he was sent to a defensive driving course. this was not a course for avoiding an accident on the way to the grocery store, but rather one on how to get away in the middle east if trouble erupted. the most important factor he relaye to me after taking the course was to inflate the tires to their max. pressure. that being said, i know on slick surfaces i will lose a little traction, but it is virginia, not montana. as far as other factors, the oil is right on the mark. i will try the injector cleaner. i blocked half the grill and i am going to look into a scanguage. i probably won't get the scanguage if the trade off versus mpg is too high. maybe some of you can tell me if there is other benefits to the scanguage.
    fikey
  9. JimboK

    JimboK One owner, low mileage

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    I highly recommend the ScanGauge. In addition to helping you maximize fuel economy by seeing better what's happening beneath the hood, it also has a variety of trip gauges and will display diagnostic trouble codes. And it's plug and play, requiring no installation and, therefore, making it easy to move between cars.
  10. diamondlarry

    diamondlarry EPA MPG #'s killer

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    I second Jim's recommendation on the Scangauge. One of the gauges he mentioned was coolant temperature which can be useful in knowing where you are in the warm-up stages(S1-S4) so you can take full advantage of them.
  11. nealo

    nealo New Member

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    Hello all. New member here. I actually found this thread via a Google search. I have seen a recent (last 2 weeks) drop off in mileage as well (from about 47ish to 41 and even as low as 39 on my latest tank).

    I live in Midlothian, Va. (a suburb of Richmond, Va.) and temps have been considerably colder than normal. This is the only intervening variable I can think of...
  12. qbee42

    qbee42 My other car is a boat

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    That's a normal drop in cold weather. It's -8°F (-22°C) here at the moment, so consider yourself lucky.

    Tom
  13. JimboK

    JimboK One owner, low mileage

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    Hey, welcome from one of your neighbors (off Providence Road near Midlothian Tpk.)!

    I'll make the same offer to you as I did previously to Fikey13: A hands-on clinic. I can show you how I get 60+ MPG even in our recent weather.
  14. nealo

    nealo New Member

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    I'm in Brandermill. Might take you up on that. However, the mileage is mostly due to my wife getting her hands on the car so often ;). I can keep it in the 50's pretty consistently.
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