Why so long for car to warm up and get the good mileage?

Discussion in 'Gen 3 Prius Fuel Economy' started by lizardacres, May 7, 2013.

  1. lizardacres

    lizardacres Junior Member

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    It seems like it takes an awfully long time for the good mileage to get going from a cold start - even when it's warm outside. Why is this? What has to happen? The last 5 miles of my commute are great, but the first 10 miles not so much. How much effect does ambient air temperature have on this process?
     
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  2. gliderman

    gliderman Active Member

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    I think its part warm up, but more power up.
     
  3. bisco

    bisco cookie crumbler

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    it's probably for pollution reasons, but 10 miles? i have a 7 mile commute and never had any problem getting 60 mpg's measured at the pump.
     
  4. Wayward

    Wayward Member

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    I see your in AZ. you shouldn't be having that long of warm ups.
    It was the hottest day we have had since I bought mine today heading home from work today.
    I left my parking lot, got to the main road, went up a slight hill for one block, then I get to coast the next 4 blocks down a slight incline which is nice because I can average between 75 and 100 mpg even during warm up, and I am in EV mode by the time I get to the bottom of the hill.
    On days when it was 30 degrees colder it took the next mile after the turn at the bottom of the hill to hit EV.
    In the mornings when it was 30 degrees out it would take 3.5 miles to hit EV mode.
    My commute is only 12 miles each way and I average around 54-56 mpg in the afternoon, and I have hit 61.1 mpg once so far.
    Average in the mornings when it's much colder I average about 46, it was 53 degrees on the way in this morning and I averaged 54.6 on the way in this morning.
     
  5. F8L

    F8L Protecting Habitat & AG Lands

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    Yes, the colder it is outside the longer it will take to reach operating temperature.

    Depending on how hard you are working the engine, it can take more miles/time to warm up. It takes about 3-4 miles or so for mine to warm up at 50F ambient and thats with getting right onto the freeway. A slow urban commute could take even longer.

    All cars do this. The Prius actually reaches operating temp faster than a lot of cars. You just don't notice it as much because the mileage in a non-Prius generally sucks and the car doesn't have a big mpg indicator glowing in front of your face. :)
     
  6. Red09

    Red09 Junior Member

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    I was noticing this same thing today. The temp was 84 out side and it took longer for my engine to shut off then it did last week with an outside temp in the 50's. Some times when I do a hard acceleration to force more heat out to the converter it helps to shut the engine down sooner but not today. Had me puzzled. Last week I could get 3.4 L/100 but today I was at 4.0L/100 on the same route only difference was hotter this week. I did not use the AC.
     
  7. lizardacres

    lizardacres Junior Member

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    Is a scan gauge the only way to know the engine temp?
     
  8. Red09

    Red09 Junior Member

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    That's what I use, a scan gauge II.
    My engine normally will start shutting down above 145, today it was up past 160 and still would not shut off like normal.
     
  9. F8L

    F8L Protecting Habitat & AG Lands

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    *Edit*

    What was your SOC?
     
  10. fuzzy1

    fuzzy1 Senior Member

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    No, there are a number of competing products that show the same information. Some are stand-alone, some display through use an existing smartphone or GPS or computer.
     
  11. GasperG

    GasperG Senior Member

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    I'm observing the same thing. In the morning I have around 150 m elevation drop on the 18 km (11 mile) way to work. If the engine is warmed up I once got a record of 2,6 l/100 km (90 MPG) but at temps of 50°-60° F in the morning and cold engine I'm struggling to get 3,6 l/100 km (65 MPG) with the heather OFF. On the way back that elevation takes it's price and I'm lucky if I see 4.0 l/100 km (59 MPG) round trip, in the winter with little heather use and colder temps I struggle to get 4.6 (51 MPG) no grill blocking.

    Recently I did a longer drive with no highway (30 MPH avg.), outside temps of 77° F, with cold start 3 hour stop at the destination and then back home and I managed an incredible 3.1 l/100 km (75 MPG) on the 80 km (50 mile) route.

    I did try different techniques of warming up but did not find a measurable difference, any pointers how to do drive a cold engine that is warm enough to shut down during a glide but does not yet deliver efficiency? Doing a longer slower pulse or a quicker more powerful and then glide?
     
  12. Red09

    Red09 Junior Member

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    6 blue bars the same as it always is on my return commute. I did not check the actual from the scan gauge.

    Could be one of the times that the display has not caught up the the actual charge. Good idea I will check today if it happens again.
     
  13. Red09

    Red09 Junior Member

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    Today was a better day, I got my warm weather normal average (3.4L/100Km) for my trip home.
    SOC was 56% at startup down to 54.5% when got out on the hiway then back up to 56% where it spends most of its time.
     
  14. F8L

    F8L Protecting Habitat & AG Lands

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    That's interesting. SOC on my GenII liked to be between 61-64.5%.
     
  15. Red09

    Red09 Junior Member

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    Mine does get up that high on occasion but normally in the high 50's.
     
  16. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Engine oil has to heat up to thin out.
    Engine coolant has to heat up so the engine computer is in a gas mileage mood, it wakes up in a anti pollution mood, as it should.
    Catalytic converter has to warm up. (same as above)
    Tires warm up and roll better.
    ATF has less drag when warm.
    A/C works hard to cool the cabin and has less work to do once the cabin is cool.
    Batteries charge up when you start cruising, then don't need the power they did while charging.
    Air under the hood warms up, warmer intake air is more fuel efficient.

    All of this takes longer when the Temp outside is colder.
     
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