Tips for increasing gas mileage in the cold?

Discussion in 'Gen 2 Prius Fuel Economy' started by Heera, Feb 2, 2019.

  1. Heera

    Heera New Member

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    Been loving my '07 since I got it in August, but this is my first (midwest) winter with it and ever since the polar vortex and the temperatures have gotten real cold my gas mileage has been terrible. I average 40-44MPG with careful driving and not using the heat. But the last few days have had me averaging 30MPG, at best. It still starts up with no hiccups, thouvh
     
  2. exstudent

    exstudent Senior Member

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    Maybe an engine block heater (Engine Block Heater for 2010-2015 Toyota Prius - PriusChat Shop) and an oil pan heater (search "oil pan heater")? This assumes you park where there is a 120V AC outlet nearby to plug into. A timer would be good to get so it turns only say an hour (or however long it needs to be) before you leave for work the next day. Maybe a big sign on the steering wheel to remind you to unplug the extension cord before driving away.

    Maybe block the grill?
     
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  3. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    I'd second block heater. We had it installed eight-o'clock-day-one, and use it almost without fail, for the first cold start of the day, year 'round. I'd recommend 2 hours any time of year; this'll plateau the coolant temp, about 25~30C above ambient. In extreme cold, 3 hours is lkely beneficial.

    You will eventually screw up, forget to unplug, so plan for it:

    1. Use an extension cord that'll pull right out, easily, and won't drag down the driveway: tie it or loop it to something (the barbecue leg in my case).

    2. Where the block heater cord comes out of the grill, double zip tie, tight, and ensure it doesn't hang out enough that it will drag.

    Also would second grill block. If you're not sure play it conservative. Determine where your Inverter radiator is (top or bottom) and only block that portion 50%, at most. In mild times don't block it. The other portion, upper or lower, I would block 50% when ambient temps are between 50F and 32F, and 100% if temps are staying below 32F.

    Also, something that works effectively for me on a 3rd gen Prius, especially when it's partially warmed: turn the heater off as you roll up to stops, say red lights are whatever. Then the engine is much more likely to shut off; the car's computer see's the low heat demand. You can also experiment with just lowering the cabin temperature, that might be enough. Be safe though: if your windshield's fogging up or something, don't go nuts with this.

    One thing, regarding block heater purchase, Prius Shop seems to be having "issues". Check with a dealership, see if they can get it. For some sand-pounding reason, I can easily buy it at my balmy west coast Canada dealership, but someone in Fargo, North Dakota, it's like buying whisky during prohibition??

    Also, the install is not a lot of fun. Research it, there are guides, official instructions (I think, hope), and online DIY instructions. The part itself is maybe $60~90. If you can get installed price around $200~250 I'd consider it.
     
  4. Paul Schenck

    Paul Schenck Active Member

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    I’m going to disagree with with some of my favorite PC friends here.
    Block heater is not the way I would go. The Prius engineers addressed this problem with 5w30 full synthetic oil and the coolant thermal reservoir. My testing in the Sierra mountains indicate best practice. Is to reset the computer (battery disconnect). Then start the car and drive in the colder conditions. The cars computers adjust the fuel algorithms to optimize your mileage.
    Use the a/c auto setting to maximize the energy efficiency, don’t use max hot as is is an energy suck.
    Don’t sit around and let the car heat up, just set a/c on auto 72 and let it decide when to increase the speed of the fan as the ICE provides the heat desired as part of the drive.
    In colder weather starting the car and driving it uphill first facilitates warming the ICE with higher RPM 3200 vs 1500 ( that’s a difference of 12,800 explosions per min to 6000 explosions. Therefore Driving it down a long hill first thing does not take full advantage of the hybrid system and is not a fuel efficient way to operate the car.
    Theoretically turning the A/C off and waiting until coolant has warmed to 180 F would work as well if driving uphill on cold mornings was not possible.

    Respectfully


    iPhone ?
     
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  5. Kaptainkid1

    Kaptainkid1 New Member

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    I heard blocking the lower and possible upper front grille vents helps keeps the engine warm in cold weather. It's also helps main heat in the engine block for weather under 38 degrees. I heard foam from home depot cost is about $10 for this mod and should help with lost in mileage during winter.

    Lower air intake block insulation | PriusChat
     
  6. fuzzy1

    fuzzy1 Senior Member

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    Note that you have a Gen2, but the thread you linked is for Gen3. The section you can fully block, vs the section that should remain partially open, are reversed from Gen2 to Gen3.
     
  7. Paul Schenck

    Paul Schenck Active Member

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    Additionally the electron a water pump knows what temperature of the water is and the electronica control module regulate how much is pumped through so relax the engineers already the job


    iPhone ?
     
  8. fuzzy1

    fuzzy1 Senior Member

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    That is a SoCal answer, not a Polar Vortex Territory answer.
     
  9. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    To maybe clarify: you don't want to block the grill portion with the inverter coolant radiator any more than 50%. In gen 2, the inverter cooler radiator is behind the lower grill opening, and in gen 3 it's behind the upper grill opening.
     
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  10. oil_burner

    oil_burner Member

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    it varies with how cold it gets. I have been blocking my grill for a couple of winters now. The best is to download the torque app and get a bluetooth obdii transmitter to monitor your inverter and coolant temperatures. I only know celcius so you'll have to do your own conversions.

    Coolant should be 80-90C for best fuel economy
    Inverter and MG1/MG2 temps should be above 30C, and can safely run above 55-60C.

    Depending on your driving, city/highway, and how cold your winters get, adjust grill block to hit these numbers. I have found in Canada with temps staying below -10C it is impossible to overheat the engine with both grilles entirely blocked. (and I mean completely sealed with duct tape so zero air gets in) I also run a block heater on a timer 4 hours before my commute, it makes a difference.
     
  11. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Here's another place you can block, year 'round.

    IMG_0185.JPG
     
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