Cold weather = bad gas mileage?

[TwoTalons]

You ever notice how much higher your idle speed is when you start your car in cold winter weather as compared to when it's warm in the summer months?? More fuel used. It takes more fuel to warm your car up in the winter than in the summer. I guarantee it. Your coolant may be coming up to operating temp in the nearly the same amount of time, although I don't see how that's possible, but that doesn't mean your engine and everything else attached to it is fully warmed up yet.

The fluids in trannys, xfer cases, and rearends gets thicker in the cold. Until those fluids warms up, they're adding parasitic loss to the drivetrain. This all adds up to more fuel consumption. One of the nice benefits of synthetic fluids is they don't get thick in the cold like regular dino oils & lubes do. I remember having conventional fluids in one of my DSMs and parking on an incline in the winter. After sitting overnight in near zero degree temps, it would not roll back in neutral. It was like I still had the parking brake on. After switching to synthetics, it was like releasing the parking brake.

[NOT THE BLUE LAMPSHADE]

I thought I was going nuts out here at WyoTech. I get about 20% less fuel economy in this cold out here!! And I'm at like ~7500ft. about too if that matters with gas consumption.

More air(denser and lower elevation and cold) = more fuel to get A/R
Less Air and Less Dense+Freezing Air = opposite?

I dunno.

[niterydr]

Originally Posted by NOT THE BLUE LAMPSHADE

I thought I was going nuts out here at WyoTech. I get about 20% less fuel economy in this cold out here!! And I'm at like ~7500ft. about too if that matters with gas consumption.

More air(denser and lower elevation and cold) = more fuel to get A/R
Less Air and Less Dense+Freezing Air = opposite?

I dunno.

Air and fuel molecules need to find matching dancing partners. If you have 1470 air molecules and 100 fuel molecules, then you have a 14.7:1 afr.

If you have a more dense air charge, aka 2940 air molecules, you need 200 fuel molecules to get that 14.7:1 ratio.
Make sence?
Colder air is more dense=more air molecules.
Its why inefficent turbo setups can "overboost" in cold weather and heat soak/have boost fade in hot summer months, they are getting more air molecules and are at an advantage on the compressor side of things and that carries thru the system to the engine. Most of the time engine bay temperatures balance out after the car is up to operating temperatures, but a car WILL make more boost @ 0 degrees versus 100 degee intake air temperatures if the system isn't setup/tuned properly to avoid that.

[Andrew7dg]

Originally Posted by niterydr

Air and fuel molecules need to find matching dancing partners. If you have 1470 air molecules and 100 fuel molecules, then you have a 14.7:1 afr.

and BOOM!!


Had a question about heat coming into the car from the heater. It seems like my car is always kind of cold. It doesn't get truly warm until it is on the highway. I mean I get heat out of the car pretty soon but not hot temperature like it is on the highway. I removed the A/C condenser because of weight and that opened up the radiator for more cooling. Did that have anything to do with it? Do I have a bad thermostat or is the engine running that cool when around town? Coming off the highway it stays warm.
Fluid level is good also.

[niterydr]

Originally Posted by Andrew7dg

and BOOM!!


Had a question about heat coming into the car from the heater. It seems like my car is always kind of cold. It doesn't get truly warm until it is on the highway. I mean I get heat out of the car pretty soon but not hot temperature like it is on the highway. I removed the A/C condenser because of weight and that opened up the radiator for more cooling. Did that have anything to do with it? Do I have a bad thermostat or is the engine running that cool when around town? Coming off the highway it stays warm.
Fluid level is good also.

Check your coolant temps via logger. You should still get to operating temperatures, but you could have a failing t-stat.

[niterydr]

Originally Posted by TwoTalons

You ever notice how much higher your idle speed is when you start your car in cold winter weather as compared to when it's warm in the summer months?? More fuel used. It takes more fuel to warm your car up in the winter than in the summer. I guarantee it. Your coolant may be coming up to operating temp in the nearly the same amount of time, although I don't see how that's possible, but that doesn't mean your engine and everything else attached to it is fully warmed up yet.

The fluids in trannys, xfer cases, and rearends gets thicker in the cold. Until those fluids warms up, they're adding parasitic loss to the drivetrain. This all adds up to more fuel consumption. One of the nice benefits of synthetic fluids is they don't get thick in the cold like regular dino oils & lubes do. I remember having conventional fluids in one of my DSMs and parking on an incline in the winter. After sitting overnight in near zero degree temps, it would not roll back in neutral. It was like I still had the parking brake on. After switching to synthetics, it was like releasing the parking brake.

More fuel consumption due to a higher IAC offset values (larger steppers values) because the ICS motor is directly related to coolant temperatures? YES
Longer time in warm up enrichment, due to the ICS Motor values being a higher value and it spending more time outside of operating coolant temperature minimums? YES

Needing more fuel so the car will run "warmer"? NO, the car burns more fuel because it is in warm up enrichment longer.



FYI, I think we are agreeing I just broke it down a bit so it made sense to me.