Cold weather makes your gas milage go down?

[JEDI]

If so, how+why? (assuming no change in gasoline. ie: no winter blend)

Thx

 

[spaceman]

running the heater more?(i have no idea if this uses more fuel)

 

[ohtwell]

I don't know much about cars but I would assume that it's because people will leave the car running for a while to heat it up and to defrost the windows.


: ) Amanda

 

For the 10,000th time.

Winter gasoline blends reduce fuel mileage

Warming up vehicles

Vehicles stay in closed loop for longer periods of time (Less efficiant)

Heavier use of A/C (The defroster turns the A/C on to dry the air)

 

[iamwiz82]

Originally posted by: Roger
For the 10,000th time.

Winter gasoline blends reduce fuel mileage

Warming up vehicles

Vehicles stay in closed loop for longer periods of time (Less efficiant)

Heavier use of A/C (The defroster turns the A/C on to dry the air)

I'd like to add:

Snow and ice on the outside of your car add to wind resistence, creating lower gas mileage

 

Along with spinning tires, but I did not include these because some parts of the country recieve cold weather but no snow.


Oops, I forgot, increased oil viscosity creates drag on internal engine parts.

 

[LeeTJ]

Originally posted by: iamwiz82

Originally posted by: Roger
For the 10,000th time.

Winter gasoline blends reduce fuel mileage

Warming up vehicles

Vehicles stay in closed loop for longer periods of time (Less efficiant)

Heavier use of A/C (The defroster turns the A/C on to dry the air)

I'd like to add:

Snow and ice on the outside of your car add to wind resistence, creating lower gas mileage

cute, snow on the ground means more tire slippage also reducing your mileage. not much i'm sure.

 

[KGB1]

Dude... no wonder, I was getting 16.5 mpg on my 4.3l astro usually but this month its been 13.8 mpg. Its freagin bad man.. plus i drive much less (warm up car in 1:30 minutes)
and i don't have a lead foot.

So all this winter I'm trying to save gas yet its futile... 🙁

 

[JEDI]

Originally posted by: Roger
For the 10,000th time.

Winter gasoline blends reduce fuel mileage

Warming up vehicles

Vehicles stay in closed loop for longer periods of time (Less efficiant)

Heavier use of A/C (The defroster turns the A/C on to dry the air)

what's closed loop?
the defroster on my 2002 chevy prizm doesnt turn on the a/c. it's always hot air blowing out

 

[LeeTJ]

Originally posted by: XFILE

Originally posted by: Roger
For the 10,000th time.

Winter gasoline blends reduce fuel mileage

Warming up vehicles

Vehicles stay in closed loop for longer periods of time (Less efficiant)

Heavier use of A/C (The defroster turns the A/C on to dry the air)

what's closed loop?
the defroster on my 2002 chevy prizm doesnt turn on the a/c. it's always hot air blowing out

even if the air is hot, a/c is still on. it still dries out the air. i turn on ac w/ temp at hot all the time cause my windows don't fog up as much then.

 

[Sundog]

Originally posted by: XFILE

Originally posted by: Roger
For the 10,000th time.

Winter gasoline blends reduce fuel mileage

Warming up vehicles

Vehicles stay in closed loop for longer periods of time (Less efficiant)

Heavier use of A/C (The defroster turns the A/C on to dry the air)

what's closed loop?
the defroster on my 2002 chevy prizm doesnt turn on the a/c. it's always hot air blowing out

If your vehicle has air conditioning and you turn on the defrost, it automatically engages that air conditioning compressor. You don't have a choice.

 

what's closed loop?
the defroster on my 2002 chevy prizm doesnt turn on the a/c. it's always hot air blowing out

The ECM (The computer that controls engine/Tran functions) run in two distinct modes ;

Open Loop = All parameters are set to a specific value, Timing, injector pulse width etc.

Closed Loop = The ECM draws data from the engine sensors (O2 , coolant , manifold pressure etc) and precisely controls and continually adjusts the timing and fuel flow.

Even though you feel heat coming out of the defroster vents, the A/C compressor is still running, GM and many other auto makers have the A/C running in defroster mode to dry the air so the windshield defrosts quicker, this is accomplished by first cooling the air, then reheating it before it is discharged into the cabin compartment.

 

[Insane3D]

You guys are forgetting an obvious one. In the warmer months, the air is generally more humid, and holds less oxygen. This is one of the reasons your vehicle doesn't make as much horsepower on humid days. The cooler and drier the air, the higher the oxygen saturation, which in turn translates into more horsepower. The colder the air is, the drier it tends to be, and the more oxygen it has. Also, the cooler the air intake charge is entering your motor, the more fuel can be burned. This is one of the main reasons drag cars but up great times on those cool dry spring evenings.

🙂

 

[geno]

If your vehicle has air conditioning and you turn on the defrost, it automatically engages that air conditioning compressor. You don't have a choice.

Not on my car, the A/C comes on sporadically.

Anyways, everything Roger and iamwiz pointed out is correct. I think the biggest effects on fuel milage have to do with warming up, and the fact that cars will run richer in colder weather ( ties in with the Closed Loop point)

 

You guys are forgetting an obvious one. In the warmer months, the air is generally more humid, and holds less oxygen. This is one of the reasons your vehicle doesn't make as much horsepower on humid days. The cooler and drier the air, the higher the oxygen saturation, which in turn translates into more horsepower. The colder the air is, the drier it tends to be, and the more oxygen it has. Also, the cooler the air intake charge is entering your motor, the more fuel can be burned. This is one of the main reasons drag cars but up great times on those cool dry spring evenings.

So you are stating that people race around more often, thereby burning more fuel in the winter than in the summer ?

If an engine makes more power/burns more fuel, you tend to press on the accelerator pedal less to accelerate to the desired speed, correct ?

 

Not on my car, the A/C comes on sporadically.

You have a low freon charge, this causes cycling of the A/C compressor.

 

[geno]

I do? 😕 My A/C blows nice and cold in the summer though...

 

I do? My A/C blows nice and cold in the summer though...

Then the drain in your heater box is plugged, this allows condensation to drain, if this is plugged, ice will form and cycle the A/C compressor 😉

 

[Insane3D]

Originally posted by: Roger

You guys are forgetting an obvious one. In the warmer months, the air is generally more humid, and holds less oxygen. This is one of the reasons your vehicle doesn't make as much horsepower on humid days. The cooler and drier the air, the higher the oxygen saturation, which in turn translates into more horsepower. The colder the air is, the drier it tends to be, and the more oxygen it has. Also, the cooler the air intake charge is entering your motor, the more fuel can be burned. This is one of the main reasons drag cars but up great times on those cool dry spring evenings.

So you are stating that people race around more often, thereby burning more fuel in the winter than in the summer ?

If an engine makes more power/burns more fuel, you tend to press on the accelerator pedal less to accelerate to the desired speed, correct ?

No. When the air is colder and drier, it holds more oxygen. More oxygen entering your engine allows for more fuel to be burned regardless of how you are using the accelerator. It's like a supercharger. It lets the engine make more horsepower by forcing in more air than normal. The more oxygen in the air/fuel mixture, the more fuel can be burned each firing. A combination of this and the other things mentioned in this thread are the cause of worse fuel mileage from what I understand. 🙂

 

[Sundog]

Originally posted by: Insane3D

Originally posted by: Roger

You guys are forgetting an obvious one. In the warmer months, the air is generally more humid, and holds less oxygen. This is one of the reasons your vehicle doesn't make as much horsepower on humid days. The cooler and drier the air, the higher the oxygen saturation, which in turn translates into more horsepower. The colder the air is, the drier it tends to be, and the more oxygen it has. Also, the cooler the air intake charge is entering your motor, the more fuel can be burned. This is one of the main reasons drag cars but up great times on those cool dry spring evenings.

So you are stating that people race around more often, thereby burning more fuel in the winter than in the summer ?

If an engine makes more power/burns more fuel, you tend to press on the accelerator pedal less to accelerate to the desired speed, correct ?

No. When the air is colder and drier, it holds more oxygen. More oxygen entering your engine allows for more fuel to be burned regardless of how you are using the accelerator. It's like a supercharger. It lets the engine make more horsepower by forcing in more air than normal. The more oxygen in the air/fuel mixture, the more fuel can be burned each firing. A combination of this and the other things mentioned in this thread are the cause of worse fuel mileage from what I understand. 🙂

And this happens on fuel injected cars also, or does the computer compensate?

And at what point is there too much air, meaning your vehicle is running too lean a mixture? It happens at some point....we have to adjust the jets on our wood splitters depending on the how cold or warm it is.

 

[catnap1972]

Originally posted by: Roger

what's closed loop?
the defroster on my 2002 chevy prizm doesnt turn on the a/c. it's always hot air blowing out

The ECM (The computer that controls engine/Tran functions) run in two distinct modes ;

Closed Loop = All parameters are set to a specific value, Timing, injector pulse width etc.

Open Loop = The ECM draws data from the engine sensors (O2 , coolant , manifold pressure etc) and precisely controls and continually adjusts the timing and fuel flow.

You've got your terminology reversed...open loop is specific, closed loop is sensor feedback driven.

 

No. When the air is colder and drier, it holds more oxygen. More oxygen entering your engine allows for more fuel to be burned regardless of how you are using the accelerator. It's like a supercharger. It lets the engine make more horsepower by forcing in more air than normal. The more oxygen in the air/fuel mixture, the more fuel can be burned each firing. A combination of this and the other things mentioned in this thread are the cause of worse fuel mileage from what I understand

You are not understanding what I am saying, if the engine produces more power, the accelerator pedal does not need to be depressed as hard, therefor you burn less gasoline, this evens out the equation.

You are still moving the vehicle the same distance per gallon burned, think about this very carefully.

 

You've got your terminology reversed...open loop is specific, closed loop is sensor feedback driven.

Sorry, you are correct, still have not had my morning coffee 😉

I'll go back and change it 🙂

 

[Insane3D]

I understand what you are saying, but the horsepower gains are not such that it actually affects how you use the accelerator. If you get up to speed and are going 30MPH on a level road for 5 miles on a 80 degree and 70% humidity day, and also on a 30 degree, 30% humidity day, you will use more gas on the latter day. The car is burning more fuel at the same RPM.

 

Incorrect assumption, colder air does not decrease engine efficiancy, please explain why cold air would decrease engine efficiancy.