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Dramatic changes after 4000 mi road trip

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by nickwelch, Oct 24, 2013.

  1. nickwelch

    nickwelch New Member

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    I have relied on all your helpful insights since buying my Prius and now have a puzzling situation. Thanks in advance for your support.

    I bought a used 2008 Prius just over 2 years ago. At the time it had about 65,000 miles. I'm a teacher and for the last two years I worked in the Boston area and had a long commute of an hour each way. My MPG was normal -- around 48-49 in the warm months, a little lower in winter.

    This past summer I moved to Seattle and drove across the country for 3 weeks. This trip was about 4000 miles and the Prius was packed with our belongings, including a Yakima box on the roof and a bike mounted to a rack on the trunk. It wasn't a crazy amount of weight, but the car definitely rode a lot lower. As expected, our FE was much lower during this trip and ended at 42.7 MPG for the whole journey. Total mileage on the car after the trip was 109,000.

    As soon as we got to Seattle we got an oil change at a Toyota dealership and replaced all four tires, as one of them had developed a very noticeable bald spot. We put on four Michelin Energy Saver A/S tires and inflated to 44 psi front/40 psi rear, the same pressure that we had for the road trip.

    My commute is now only 10-12 minutes and rather hilly. After 3 months in Seattle my MPG has dropped precipitously. At first it was in the 44 range, but for weeks now I'm getting 41-42. I rechecked tire pressure at 44/40. I don't use AC or heat. From reading the great threads on this forum I know about many of the common killers of FE (colder weather, shorter trips) but I'm nevertheless surprised and, frankly, concerned at this drop. I'm worried something happened to the car during our road trip, like we "fried" the engine or battery or just overworked it.

    Let me know what other details would help. Thanks for your help.
     
    #1 nickwelch, Oct 24, 2013
  2. Eclipse1701d

    Eclipse1701d Prius Enthusiast

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    You mentioned you had an oil change. If the tech over-filled it will adversely affect your MPG's. Gen II's like it a slightly below the max line on the dipstick... I would check that first. Other things would be dirty air filter, clogged cabin filter, or a failing 12Volt battery. New tires will also lower your MPG's. You will notice and increase once you get 7500 to 10000 miles on them.

    Also, the new tires and the shorter trips combined are both lowering your MPG's. The other things mentioned above will contribute to that if any of those conditions exist.
     
    #2 Eclipse1701d, Oct 24, 2013
  3. qdogfball

    qdogfball Junior Member

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    Hills will make your mpg go down.

    Check on your 12 V Battery. There are threads on how to do this without special equipment.

    There are also threads on why this lowers the mileage.
     
    #3 qdogfball, Oct 24, 2013
  4. nickwelch

    nickwelch New Member

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    Thanks for the tips. I will check the oil and 12V battery. It does sound like this mix of factors could be responsible, but is 41-42 MPG not abnormally large of a reduction from before? That was the source of my worry.
     
    #4 nickwelch, Oct 24, 2013
  5. edthefox5

    edthefox5 Senior Member

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    I would do some maintenance.

    At 109K:

    Your due for engine coolant change
    Way way overdue for Inverter coolant change
    Way way overdue for transmission fluid change
    Water pump belt replacement
    Spark plugs----If for nothing else to break them free in that aluminum head engine and inspect them.
    They're out might as well replace them. Replace with original Denso's.
    Way overdue for throttle body cleaning

    You will see some improvement in mpg with the Inverter coolant change and new plugs.
     
    #5 edthefox5, Oct 24, 2013
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I would say you are getting great mpg considering that the engine takes 5 minutes just to start warming up and your commute is 10-12 minutes, not to mention the hilly terrain. Don't worry, your car is performing well.

    As previously suggested, you need to have the major service items at 100K and 120K miles performed in the near future. Good luck.
     
    #6 Patrick Wong, Oct 24, 2013
  7. Yotato Sirup

    Yotato Sirup New Member

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    One more thing to check among those suggested is wheel alignment. If that wasn't done when the new tires were put on it might be worth having done, especially since one of the last set of tires had a bald spot.
     
    #7 Yotato Sirup, Oct 24, 2013
  8. fuzzy1

    fuzzy1 Senior Member

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    Your previous 1 hour commute was almost all in a fully warmed up state, but the new 10 minute commute is mostly cold. They won't have comparable MPG. Try a longer weekend trip and see what MPG the car can produce now.

    Temperatures have been dropping here, especially in this 'Fogmageddon' inversion pattern, and winter gas blends should also be here now, so today's MPG won't match what you could get two months ago.

    Do check out your 12V battery. It is sometimes a culprit, though not often enough to shotgun it without checking first. For any easy GenII test from the driver seat, see this post: Weird stuff happening? MPGs dropping? Test The Battery
     
    #8 fuzzy1, Oct 24, 2013
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