Gas mileage way down, advise?

[fishuhalik]

Normally, my car gets 24-27mpg in the winter, even in the coldest of the cold days, but lately I'm barely getting 20. Wondering what's causing it? I replaced the plugs and filter this fall, any other ideas? It's a Ford Contour SVT, 2.5ltr v6, and runs on premium (92 or better octane), 160k fairly rough miles on it, I'll just say I drive it like it was made to be driven.

Other than the drop in milage I haven't noticed anything else wrong with the car, power's still the same and it's running like a top.

[BoxMN]

Tire pressure, new plug wires...?... Is it still running the same? I put new fuel pressure regulator in a 3.1 liter Malibu, and along with a vacuum hose to the PCV it got me back to 26 from 20 mpg.

BTW - I am no mechanic so take my info with grain of salt

[Macgyver55]

Even short warm ups dig into mileage numbers, low tires are more common in the winter, and a bit of snow will take its toll too. Add the extra drag on the motor from all of the accessories and its a recipe for worse mileage. If all these factors are consistent with the past, but mileage is still less it may be tough to zero in on unless you have some other symptoms to chase. I'd see if it gets better when the temps go up some. If not, you'll need to have a more thorough check on the system.

[fishuhalik]

I was wondering macgyver, sometimes I do let it warm up for 10-15 minutes before work. That's not gonna change the overall milage, I've always done it, but how much gas do you think it burns letting it run for that long? Some of the guys here turn there vehicles on an hour before turn-in and I wait till later cuz well, I'm cheap and don't wanna burn too much gas, but if it's only $1 in gas I'd be more than willing to pay that to jump into a toasty warm car when it's -20!

[fishuhalik]

Oh, and the tires are fine, I check pressure every monday, along w/ all the fluids

[CITY LIMITS]

It may be from warming it up if you think about it you warm it up,everytime you drive it deff adds up over time .

[fishuhalik]

I know it affects my mileage, but I always let it warm up last year, same 10-15 minutes, and always got mid-upper 20s.

[Macgyver55]

Every motor will use a different amount when idling depending on its size, state of tune and the temperature. And, because a cold engine uses more fuel to run than a warm one, the warm up period is the least efficient. A standard average is about .015 gallons in 10 to 12 minutes. I'm sure others can find different numbers but this is a reasonable estimated amount.

Technically it does lower the mileage because when warming up you get ZERO mpg. Often, warmups are longer than people think and more frequent. If you really want to find out for sure, try checking your mileage without warming the motor more than a minute or two for an entire tank. I think you will be surprized at the difference.

[deadeye]

Those cars tend to have cat problems. Given that you know what car u got and drive it hard it will burn the cats up quick. Could be time for a resonator swap.

Could be a problem o2 sensor too. I have had 2 recently that were bad but didn't throw a code. Given that was a Turbo car running rich but running wot with a NA car is usually on the lean side burning them up fast too.

[BobT]

Quote:

I was wondering macgyver, sometimes I do let it warm up for 10-15 minutes before work. That's not gonna change the overall milage,

Actually I think it can have a rather dramatic affect.

I bought my new 2009 truck this past July. The first thing I did was reset the AVG MPG record in the computer so that it started fresh from the day I bought it.

I currently have about 5,200 miles on the truck so it is enough to give a fair idea of my average miles but low enough that it can change relatively easily yet. The higher the records go the more stable the value will become.

A month ago before the temperatures started heading below zero so much my average was at about 16.9. Due to the below zero mornings and single digit daytime highs I let my truck warm up a little more than normal. Normal for me is about 60 seconds but now I let it go about three times that long. Note that I take it pretty easy on my vehicles for the first few miles until things get warmed up.

Anyway, I have actually been able to see the average miles per gallon drop as I have been doing this. It is now fluctuating between 15.9 and 16.0. Cold weather does take its toll on mileage.

I expect that next summer I will probably see that average climb back up to around 17 again.

[DTro]

The cold weather alone will decrease gas mileage in the way the thermostat operates, add that to the fact that the ethanol content in the gas is greater in the cold months, that will also decrease your mileage.

I always take into account the fact that I’m driving on “winter gas”.

But since you checked your tires already, and you are seeing a dramatic drop, I would check both the Catalytic Converter and the Injectors.

[Scott K]

Being that the MAF is the main input for fuel, I would remove it and clean the heating element with CRC brake clean in the red can.

Idling your engine in the winter is a huge fuel consumption, figure about 1 gallon per hour, on a v6 engine. Warming up your car 2 times a day, it only takes 2 days to burn a gallon. Also count in the fact you are running high octane fuel, it consumes more at cold idle. Check the fuel pressure and make sure it isnt high. When you replaced spark plugs, did you use OE? Do you have an aftermarket air filter, that will also add to idle consumption.

[fishuhalik]

bobt, I know that affects the mileage, but it wouldn't change the mileage from what I was getting last year, since I did the same thing then.

dtro, i'll check the cat & injectors, could well be the cat if what deadeye said is true.

4w, I put in oem plugs and filter.

[fishuhalik]

and thanks for the tips guys

[hamms-scooter]

Check your mass airflow sensor this will tell your computer funky things if its dirty! They have cleaners for it. A cold air intake with an air filter out of a box will make this more frequent. If running a k&n filter it may be getting some of the oil in there as well if you serviced it lately and didnt allow it to dry.

[knoppers]

I think its all about the winter grade gas, and warming the engine before driving, even a couple minutes. my milage has dropped from an average of 17 to 13.5.

I have seen milage drops in winter every year.