worse gas mileage in cold weather, does this make sense?

[Aaron]

i thought cars were supposed to get better gas mileage with colder weather bc its easier on the engine but ever since its gotten colder down here in texas my engine has gone from getting 18-19 mpg to 16-17 and im worried somethings wrong...

when i turn my car on just to move it (and it revs up high to warm up) and then i turn it off quickly it smells like gas...is this because there is a higher gas mixture in the engine to warm it up and there is a lot of unburned gas when i turn it off or should i be worried i have a gas leak since my mpg is worse?

[brownaznkid]

try resetting the ecu and see what happens... 18-19 city is pretty bad in the first place... i usually get 22-25 city

remove backup fuse from hood for a minute, put it back, start up the car and let it warm up, don't turn on anything, turn off a/c, fans, radio, etc. and don't touch the gas pedal

how high is "high" are the RPMS when you start the car initially? mine is usually 1500 RPMs which i think is normal until the car fully warms up and it drops to about 700 +/- 100 RPMs.. you could always just let the car warm up 5 mins before you leave for places.. no harm in doing that

[Fritz the Cat]

You'll sometimes notice more of a fuel smell when the car is started in colder weather because the cat hasn't heated up enough to be as effective, so the exhaust still has a bit more of the hydrocarbons. If you let it warm up for a few minute you'll probably notice less of a gas smell. And yes your car is probably running a bit richer when it's at high idle anyway

[Aaron]

when its cold it revs up to 2000 rpm, will resetting the ecu help my gas mileage?

btw i have an auto

[slipstream909]

It may????? Other things to check out are your air filter and maybe your throttle body to see if they are dirty. I think you should be getting a little better gas mileage.

[aero]

geees.. anything under 20 in a cb7 stock is very bad. I could have sat at redline when i had the f22, and still gotten mid 20's. when was the last time you did a tune up, and how many miles you have?

[Aaron]

got a tune up when i bought the car in may...got the air filter replaced a few months ago...i only have 119 k on it...the automatic tranny fluid needs changing...could this have anything to do with it?

[aero]

Originally posted by Aaron
got a tune up when i bought the car in may...got the air filter replaced a few months ago...i only have 119 k on it...the automatic tranny fluid needs changing...could this have anything to do with it?

what did the tune up consist of? ATF wouldnt have much to do with it, but thats not something you wanna put off either.

[f22-dohc]

my explanation for this is that i idle more on cold weather

[Aaron]

what did the tune up consist of?

honda did it...i need to dig out the receipt and look up what all they did...i know they fixed a couple minor oil leaks and replaced a few other things

ATF wouldnt have much to do with it, but thats not something you wanna put off either.

i didnt think that would have anything to do with it

[aero]

well get that receipt, and we'll see what they forgot to do.

[accordmaniac]

In cold weather~ engine warming up~ will eat up lots of gas...

[AccordWarrior]

Plus when you car is cold, I believe it runs richer until it warms up. I know that when my car is cold, it doesn't run all that great until the car gets heated up, and I'm sure that's taking its toll on the gas mileage.

[squig808]

There are lots of things that can contribute to a decrease gas mileage when it gets colder. I'm not sure about Texas, but in Northern States and Canada here are some of them:
1. People tend to let the car idle longer to "warm up"
2. Your tire pressure will drop with colder weather, obviously you can correct this.
3. "Winter Gas" = less power per gallon
4. Until the engine heats up your engine and transmission oil will be thicker. Lighter and / or synthetic oil will help here.
5. The colder the engine is on startup the longer it will run a richer fuel mixture, due partially to a percentage of the fuel vapors condensing in the induction system.

If you combine these with frequent, short trips and no block heater and you'll notice a big drop. Again, I'm not sure how cold it gets in Texas, so maybe your drop is due to lack of maintenance or some other problem.

[Aaron]

well i have noticed that on the weeks when i have driven and it has been, on average, less cold than on weeks that it had been more cold...my gas mileage was better, so i think it is due to weather and not bad maintance

thanks