Low MPGs in colder weather?
01-25-2010, 12:41 PM
#1
MBWorld Fanatic!
Thread Starter
Low MPGs in colder weather?
Has anybody noticed a drop in MPGs in colder weather. All my cars used to do it, but I feel it wasn't too cold and I'm averaging 18-19 on highway, and 15 in town. That's about 2 less than I'm used to. Will check tire pressure and oil level. Anything else I should look at?
01-25-2010, 01:04 PM
#2
Member
Join Date: Oct 2009
Location: Ft Myers FL
Posts: 221
Likes: 0
Received 0 Likes
on
0 Posts
2010 Barolo Red-Almond/Black GLK 350, 2008 Cadillac Gold Mist LUX III DTS
Best thing to do is take your shoe off your right foot and weigh the foot.
Any chance the foot is heavier than it used to be?
Any chance the foot is heavier than it used to be?
01-25-2010, 01:09 PM
#3
Senior Member
Join Date: Oct 2009
Posts: 293
Likes: 0
Received 0 Likes
on
0 Posts
GLK350 4Matic - Loaded
Hahaha... Good one Red!
Well... I come from the land of having to warm up your vehicle for 10-15 mintues before driving on cold days so the MPGs always take a beating in cold weather!
Well... I come from the land of having to warm up your vehicle for 10-15 mintues before driving on cold days so the MPGs always take a beating in cold weather!
01-25-2010, 01:20 PM
#4
Senior Member
Join Date: Feb 2009
Location: Toronto, ON
Posts: 354
Likes: 0
Received 0 Likes
on
0 Posts
GLK 350 4matic
I do feel the same. Didn't do any study or search but I would guess its from: 1. hi rpm in colder start up. 2. Wet / snow covered road. 3. Lower real tire pressure due to cold.
01-25-2010, 03:25 PM
#5
Member
Join Date: Feb 2009
Location: Far West Texas
Posts: 163
Likes: 0
Received 0 Likes
on
0 Posts
GLK 4Matic
Here in Texas, and I'm sure in many other areas, the wintertime fuel supply is "oxygenated" to reduce emmisions. During this time, fuel mileage goes down. I wouldn't doubt that is what you are experiencing.
01-25-2010, 04:53 PM
#6
Senior Member
Join Date: Feb 2009
Location: Toronto, ON
Posts: 354
Likes: 0
Received 0 Likes
on
0 Posts
GLK 350 4matic
By Paul Brand, Star Tribune
Last update: December 29, 2005 - 4:53 PM
A Three words: "time to temperature." In cold weather, our vehicles take a much longer period of time to reach full operating temperature. And they take this extra time each and every time we start them up, even if they have not fully cooled down.
Modern engine-management systems are very efficient at optimizing the fuel/air ratio entering the engine. The oxygen sensor monitors the percentage of oxygen in the exhaust, compares this with the percentage of oxygen in the atmosphere, and generates a low-voltage signal that communicates this ratio to the computer. The computer then adjusts the pulse-width of the fuel injectors -- the precise period of time each injector is open on each injection cycle --to fine-tune the amount of fuel reaching each cylinder.
The system makes this very fine adjustment dozens of times each second, working very hard to reach the optimum air/fuel ratio for any given situation, and at steady-state cruise speed seeks to approach the perfect ratio of 14.7 to 1, called the stoichometric ratio. The system is running in a "closed loop" when it is relying upon the oxygen-sensor signal to fine-tune engine operation.
But the engine-management system can seek this optimum air/fuel ratio only when the engine is up to full temperature. In fact, the computer does not look for a signal from the oxygen sensor until it approaches full temperature. During the warm-up cycle -- which takes considerably longer in cold weather -- the computer operates on a warm-up program based on coolant temperature, mass airflow or MAP sensor input of air volume and temperature, throttle position and engine rpm. This is called "open loop" operation, meaning the system is not operating off the feedback from the oxygen sensor.
In open-loop operation during the warm-up period, the engine requires -- and is provided with -- a richer air/fuel ratio to ensure good combustion.
It needs this extra fuel for the simple reason that a percentage of the atomized, then vaporized, fuel delivered to the engine condenses into liquid gasoline on cold internal engine components such as the intake manifold, intake valves, pistons and cylinder. And remember, it's gasoline vapor, not liquid, that burns.
Until those parts warm up, the engine needs more fuel to operate with reasonable drivability. Thus, the colder the weather, the longer it takes for your engine to reach full operating temperature and closed-loop operation, and thus the more fuel the engine uses to deliver the same driving cycle. That's the primary reason your engine consumes more fuel in winter driving.
Last update: December 29, 2005 - 4:53 PM
A Three words: "time to temperature." In cold weather, our vehicles take a much longer period of time to reach full operating temperature. And they take this extra time each and every time we start them up, even if they have not fully cooled down.
Modern engine-management systems are very efficient at optimizing the fuel/air ratio entering the engine. The oxygen sensor monitors the percentage of oxygen in the exhaust, compares this with the percentage of oxygen in the atmosphere, and generates a low-voltage signal that communicates this ratio to the computer. The computer then adjusts the pulse-width of the fuel injectors -- the precise period of time each injector is open on each injection cycle --to fine-tune the amount of fuel reaching each cylinder.
The system makes this very fine adjustment dozens of times each second, working very hard to reach the optimum air/fuel ratio for any given situation, and at steady-state cruise speed seeks to approach the perfect ratio of 14.7 to 1, called the stoichometric ratio. The system is running in a "closed loop" when it is relying upon the oxygen-sensor signal to fine-tune engine operation.
But the engine-management system can seek this optimum air/fuel ratio only when the engine is up to full temperature. In fact, the computer does not look for a signal from the oxygen sensor until it approaches full temperature. During the warm-up cycle -- which takes considerably longer in cold weather -- the computer operates on a warm-up program based on coolant temperature, mass airflow or MAP sensor input of air volume and temperature, throttle position and engine rpm. This is called "open loop" operation, meaning the system is not operating off the feedback from the oxygen sensor.
In open-loop operation during the warm-up period, the engine requires -- and is provided with -- a richer air/fuel ratio to ensure good combustion.
It needs this extra fuel for the simple reason that a percentage of the atomized, then vaporized, fuel delivered to the engine condenses into liquid gasoline on cold internal engine components such as the intake manifold, intake valves, pistons and cylinder. And remember, it's gasoline vapor, not liquid, that burns.
Until those parts warm up, the engine needs more fuel to operate with reasonable drivability. Thus, the colder the weather, the longer it takes for your engine to reach full operating temperature and closed-loop operation, and thus the more fuel the engine uses to deliver the same driving cycle. That's the primary reason your engine consumes more fuel in winter driving.
01-25-2010, 07:08 PM
#7
Super Member
Yeah, what Fred said. I get 20 MPG city and highway mixed, 22 -23 highway. Never warm up the car, start and go always have.
Trending Topics
01-30-2010, 12:18 AM
#10
Senior Member
Join Date: Mar 2009
Location: Scarborough, Ontario
Posts: 360
Likes: 0
Received 5 Likes
on
4 Posts
2020 CLA 250 4Matic Black
Well the 91 octane I use does not have any ethanol, if I can believe the sign.
I have keep track of all my fillups for the heck of it. I keep track of the fuel consumed, distance travelled, temperature and price along with what the current "Fuel Consumption From Start" from the display.
Here are my stats from my last entry; 312 days of use
Total Kms driven 18949 Fuel:2579.845 litres litres/100Km: 13.2 MPG (Can)21.58 MPG (US)17.97 I used my math skills for these conversions but I think they are ok.
For more trivial data: Avg: Temp 13.81 Celsius Daily Cost $8.58 at the current usage, I should hit just under $3,000 for fuel for the year and travel some 20,000km.
The GLK states my fuel consumption is 13.0litres/100km from start. I know it does 1 decimal place so I am sort of wondering why its better than the real world.
I have keep track of all my fillups for the heck of it. I keep track of the fuel consumed, distance travelled, temperature and price along with what the current "Fuel Consumption From Start" from the display.
Here are my stats from my last entry; 312 days of use
Total Kms driven 18949 Fuel:2579.845 litres litres/100Km: 13.2 MPG (Can)21.58 MPG (US)17.97 I used my math skills for these conversions but I think they are ok.
For more trivial data: Avg: Temp 13.81 Celsius Daily Cost $8.58 at the current usage, I should hit just under $3,000 for fuel for the year and travel some 20,000km.
The GLK states my fuel consumption is 13.0litres/100km from start. I know it does 1 decimal place so I am sort of wondering why its better than the real world.
