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05-17-2009, 09:11 AM | #19 | |
Drives: 08 3DR 5M Bayou Blue; 09 Fos Join Date: Oct 2008
Location: New Hampshire
Posts: 622
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Quote:
extended explanation: A Heated air intake at cold start would help speed engine warmup and efficiency but generally the colder and denser the inlet air the more efficient the engine AFTER warmup. Water takes a lot of energy to heat - and your fuel is being expended in heating approx 2 gal H2O additional 40-90 degrees to Op temp in the cold winter days. There goes your fuel. 1 word - Block heater;) Last edited by TheSilkySmooth; 05-17-2009 at 09:21 AM. Reason: add more |
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05-17-2009, 10:13 AM | #20 |
Drives: 2008 Yaris Meteorite LB Join Date: Feb 2009
Location: Southern Michigan
Posts: 61
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Winter gas mileage...
My worst mileage was in January 09.....23.76 mpg. It was really cold, snowy and my trips were mostly around town....with a little warm up time. Of course, the car only had just over 1000 miles on it too. I'm looking forward to breaking 40 mpg someday...but haven't done it yet!
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05-17-2009, 11:05 AM | #21 | |
HardlyDangerous
Drives: 09 Yaris LE, H/B, auto Join Date: Jul 2006
Location: Ridgeway Ontario
Posts: 573
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Quote:
regardless the throttle position when the pistons travel from TDC to BDC they draw in the same amount (Volume) of air. In colder weather there is MUCH more oxygen and must be compensated by adding more fuel or the mixture will be lean.. there is no way around it. Sure there is longer warm ups in colder weather but this is why your engine idles much higer in sub zero temps then a cold start on a hot summer morning. Even at idle when the engine is warm, the engine still uses a lot more fuel when air temps are cold because of the much higher oxygen levels. So your sayin a HOT ENGINE, I fill up, roads are completely clear but the temps are -10 I'm nopt going to see any changes in fuel economy... BS. Engine black and water temps are normal, oils hot, tires are hot, no snow, yet a 5 strait hour treck on the highways sees far less mileage then the same trip in the summer. And that has nothing to do with there being more oxygen in the cold air? Why is it then older cars with carbs, ATV's motorcycles, outboards run so lean in cold weather.
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The early bird gets the worm, but the second mouse gets the cheese. |
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05-17-2009, 12:32 PM | #22 |
Drives: Loaded 2007 mica silver sedan Join Date: Sep 2007
Location: New hampshire
Posts: 226
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I get about 35 in the winter and 42 or so in the summer. I have a 25 mile commute to work. With the colder air in the winter the engine takes longer to heat up thus a more fuel, in the summer It takes about 1/2 mile for the engine to be at operating temp thus better mileage. normal for any car.
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05-18-2009, 09:39 AM | #23 |
Drives: 08 3DR 5M Bayou Blue; 09 Fos Join Date: Oct 2008
Location: New Hampshire
Posts: 622
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This is completely incorrect. When the engine is throttled, at a given RPM, it is operating at a vacuum and the cyl is filled with less air mass. BTW the engine does not draw in air - there is no such thing as "sucking". You are confusing displacement with air mass. AFA mileage hits in cold weather, its almost ALL coolant warmup and gear and bearing lubricant shear. In extreme cold you will see additional losses in tyre stress heat loss and oil sump Lubricant heat loss. And dont forget your heater - the energy req'd to heat the air in the cabin.
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05-18-2009, 09:47 AM | #24 |
Drives: 08 3DR 5M Bayou Blue; 09 Fos Join Date: Oct 2008
Location: New Hampshire
Posts: 622
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If you have higher oxygen contenet at given throttle opening, then ECU add fuel to compensate, then you have more heat energy, then the engine idles faster, then the ecu closes the throttle some to lower RPS count. This reduces air flow and reduces fuel utilized. and you are back to stasis.
Last edited by TheSilkySmooth; 05-18-2009 at 09:48 AM. Reason: sp |
05-18-2009, 09:52 AM | #25 |
Half a Bubble Off Plumb
Drives: 2009 Yaris Sedan Join Date: Mar 2009
Location: Bristol, Tennessee, USA
Posts: 1,593
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Colder, denser air can burn more fuel and generate more maximum horsepower, no question. There doesn't seem to be a simple, straightforward "one size fits all" answer for the optimal intake air temperature for best cruising fuel mileage. There are many posts with data and discussion on the fuel economy fora.
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