MPG going DOWN

[BigOlTater]

While big tires gulp gas, winter gas doesn't do your mileage any favors. Here in Colorado they increase the ethanol content during the winter and gas mileage definitely suffers. Does your gas formulation change with the seasons?

my 2015 LE went from 17+ to 15.5mpg the past month or so I'm I drive like gramps!!! Thanks for the info cause I was about to call Toyota up and scream B U L L S H I T!!!!!!!! $

 

[wanderMT]

Think the ambient temp has as much to do with lower mpg as the fuel blend. Run a lot richer mixture until engine reaches operating temp. Have noticed over years that my mileage suffers when temp drops - not necessarily when winter fuel is first being used in the fall.

 

[CSix]

Interesting... my other car is a turbo. Turbos love cold air she gets a bit punchy and loves going to boost. I always thought it was a problem with the cold temps affecting my ankle... wanting to push the foot on the accelerator... that drops my mileage. But, it really is the cold air! My wife will now have to believe it not me.

So, in the end, cold air, large tires, aggressive tread, winter gas and bad ankles are all factors in decreased gas mileage. ;-)

 

[diverscale]

Think the ambient temp has as much to do with lower mpg as the fuel blend. Run a lot richer mixture until engine reaches operating temp. Have noticed over years that my mileage suffers when temp drops - not necessarily when winter fuel is first being used in the fall.

Noticed the same thing. People blame winter fuel only, but here are bigger factors to consider adding to yours:

-Increased drag due to denser air (colder = denser). For every 10 degree F drop in temperature, aerodynamic drag increases by 2%.

-More pumping losses due to the engine producing more power for the same throttle opening (cold air = more fuel to pour in), by backing up the throttle slightly in lower temperatures for the same driving speed (roughly explained).

-some fuel being inefficiently vaporised by the injectors, causing inefficient burn, but read somewhere that on modern cars, this factor is now rather small.

There are much more factors to name, for example, oil viscosity in your differentials, prorably more friction from tires... Thing to remember, cold temp has every reason to kill your MPG.

Winter blend only contributes to 2% of the mileage drop.

 

[1engineer]

Noticed the same thing. People blame winter fuel only, but here are bigger factors to consider adding to yours:

-Increased drag due to denser air (colder = denser). For every 10 degree F drop in temperature, aerodynamic drag increases by 2%.

-More pumping losses due to the engine producing more power for the same throttle opening (cold air = more fuel to pour in), by backing up the throttle slightly in lower temperatures for the same driving speed (roughly explained).

-some fuel being inefficiently vaporised by the injectors, causing inefficient burn, but read somewhere that on modern cars, this factor is now rather small.

There are much more factors to name, for example, oil viscosity in your differentials, prorably more friction from tires... Thing to remember, cold temp has every reason to kill your MPG.

Winter blend only contributes to 2% of the mileage drop.

http://www.toyota-4runner.org/5th-gen-t4rs/133786-cold-air-horsepower.html

 

[gm350reratliff]

Just a few things to check;

Exactly, what air pressure are your tires set at?
Are you warming up the vehicle at all before you drive?
Are you carrying anything extra (snow chains, tools)?

Oils get thicker when cold, more resistance for your engine must push against. Even though your runner is new, you may want to have the alignment checked. I agree with the winter blend gas and cold temps from above. Every vehicle I've owned gets really bad mpg when we go to ND in the winter (my 4th gen seems to be less affected, we'll see how my 5th gen does in a few weeks).

 

[1engineer]

Just a few things to check;

Exactly, what air pressure are your tires set at?
Are you warming up the vehicle at all before you drive?
Are you carrying anything extra (snow chains, tools)?

Oils get thicker when cold, more resistance for your engine must push against. Even though your runner is new, you may want to have the alignment checked. I agree with the winter blend gas and cold temps from above. Every vehicle I've owned gets really bad mpg when we go to ND in the winter (my 4th gen seems to be less affected, we'll see how my 5th gen does in a few weeks).

The 0W-20 Synthetic will not be appreciably more viscous with temperatures ranging from 20F to 70F.
You are right on though about warming up before driving and tire pressure.
OP for reference your tires will "lose" one psi for every 15 degrees temperature drop. You could be running at 28 psi if it's 15 degrees outside even though you gauged the tires at 32 psi a week ago when it was 70 degrees and four psi will cut gas mileage appreciably.

I happen to live in a wonderful place where it was 67 degrees this past Sunday and is currently 19 degrees outside lol. We go through the whole winter this way.

 

[gm350reratliff]

The 0W-20 Synthetic will not be appreciably more viscous with temperatures ranging from 20F to 70F.
You are right on though about warming up before driving and tire pressure.
OP for reference your tires will "lose" one psi for every 15 degrees temperature drop. You could be running at 28 psi if it's 15 degrees outside even though you gauged the tires at 32 psi a week ago when it was 70 degrees and four psi will cut gas mileage appreciably.

I happen to live in a wonderful place where it was 67 degrees this past Sunday and is currently 19 degrees outside lol. We go through the whole winter this way.

True, you may not notice much viscosity change on the 0W-20 but what about the oil in the t-case, differentials?

 

[1engineer]

True, you may not notice much viscosity change on the 0W-20 but what about the oil in the t-case, differentials?

It will get "thick" but the actual efficiency loss will be limited to the first few hundred feet.

Story time:
"Once upon a time (I was designing the hydraulic system) we had some equipment that would be operating in two different places. One was the North Slope of Alaska and the other was in Antarctica. We were noobs when it came to extreme cold weather design. Sure, our stuff was operating in cold climates but this was really cold!
Anyway, we had this grizzled old wizened project engineer. I was a youngster then all full of piss and vinegar. We had our initial meetings and operation in extreme cold weather was the topic. I had done my research and was confident in my selection of hydraulic fluids, thermocouples, in tank heaters, heat blankets for components, heat tape for hoses, etc, but my mentor looked at me and asked "What about the gear boxes?" Hmmm. I hadn't thought of that. I told him I would get back to him. I found out there was no consensus in the industry on gear box fluids for cold weather applications. They were all over the map.
We had just come back from a trade show (Vegas baby) several months before and one of the displays we had was a cutaway of a new gearbox we had designed and were manufacturing. I had the brilliant idea of putting thick clear Lexan over the cutaway, sealing it up, filling the box with our favorite blend and cooling that box down to "COLD" and experimenting.
So we built a box around the box, got a five HP electric motor and coupling to turn the input shaft and built a rudimentary refrigerator using a fan and dry ice. We got it down to around -65F. We took off the box covering the see through gearbox and the fluid was a big 'ol ice cube. We turned on the electric motor (we were measuring the current draw to determine force required to turn the shaft) and watched.
Well, the first couple of turns were tough! Here is the amazing part though: After the first couple of turns the areas right around the turning gears quickly heated up and turned fine. The adjacent areas though remained solid! We knew that was not the right fluid for the applications so we ran it several times with different fluids to see what would be optimal for our boxes. We ended up using a synthetic blend. Now, we had a bunch of gears in there that needed to operate with no additional loads so that is why we went with a special blend. If we only had one gear set we could have used a normal fluid because, once you got the gears spinning, everything was OK right in the immediate areas around the gears due to heat build up due to friction. Now, if you stopped for 20 minutes you would have to go through the big power draw to get it started again though.

So, in our vehicles in extremely cold weather, the first mile or so will use more power but after that it will be fine.

 

[diverscale]

http://www.toyota-4runner.org/5th-gen-t4rs/133786-cold-air-horsepower.html

Thanks, still proves in some way my second point about pumping losses

fuel economy is not about maximum power, but how efficient the engine is running under a relatively small load and throttle input. And here is why there are more pumping losses in colder temps in part due to ''more power'' caused by a denser fuel/air mixture


let's say you need 50HP to drive at 60 mph:

In warm temperature, due to thinner air/fuel mixture, you will need "20%" throttle opening to achieve this 50HP. More throttle opening to let more air in so you get to burn the necessary fuel to produce 50HP

In very cold temp, to produce this same 50HP, "15%" throttle opening would be enough due to denser air/fuel mix, resulting in more throttle restriction in the intake manifold, and more pumping losses.

Anyway, just having fun discussing, as this is only one of many factors affecting efficiency in cold weather

And about that last link about power VS altitude and temperature; when I was in Death Valley, which is if I remember well, 7000FT at some places, and nearly 120F, the truck would be very slow compared to a normal temperature and sea level, it was astonishing. The ECU seemed to adjust down a few hundred RPM the shift points at WOT also when I was in very high altitude.

 

[NoDak]

or in the layman terms.

when you crank your engine in -30F and it goes whir whir whir, then starts and idles at 1800 rpms until 5-10 mins later it sits at 800-1000 rpms.

then you have the joy of putting it in gear and then the dash lights up cause your diff gear is still frozen solid until it warms up.

and if your really lucky, your abs is going nuts since one of your calipers is frozen solid cause you forgot to clear the snow that melted during the cool down last night onto the caliper. so you leave a nice long skid mark on the road until the wheel breaks loose.

and just to have pity on you, you have a manual transmission and you break the pedal actuator cause the hydraulic fluid is frozen in the line/cylinder when you pushed it in to release the clutch.

 

[03_4x4Runner]

or in the layman terms.

when you crank your engine in -30F and it goes whir whir whir, then starts and idles at 1800 rpms until 5-10 mins later it sits at 800-1000 rpms.

then you have the joy of putting it in gear and then the dash lights up cause your diff gear is still frozen solid until it warms up.

and if your really lucky, your abs is going nuts since one of your calipers is frozen solid cause you forgot to clear the snow that melted during the cool down last night onto the caliper. so you leave a nice long skid mark on the road until the wheel breaks loose.

and just to have pity on you, you have a manual transmission and you break the pedal actuator cause the hydraulic fluid is frozen in the line/cylinder when you pushed it in to release the clutch.

I would move south.

 

[Eagle]

tl;dr

1E built a box and a refrigerator because he was all full of piss and vinegar and he proved that things are cold until they warm up.