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Discussion Starter · #1 ·
For the past week the temps have hit low teens and below. Well my car has been getting horrrible gas milage since then. I don't know if this is normal but i wouldnt assume so. I was in iraq last winter so i cant remember how it drove 2 years ago. Also i dont know if my mods (65mm TB, true CAI, and full 2.25 ehaust headers back) have anything to do with it or not. At first i thought maybe because it was wet and cold the air filter just froze over a bit causing less air flow, but now its just cold and not wet. I got 200 miles to my last tank. and so far i have gotten 45 miles to a quater tank. I'm used to getting 75 plus to a quater tank. Any suggestions?
 

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ELVIS LIVES !
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I know in cold weather you will get worse gas milage because it takes longer to get your engine up to temp so it idles higher. But in your case I dont think that is what is going on. Do you have a performance tune? If not I have heard that a tune can help MPG and give you a little more power.
 

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Discussion Starter · #3 ·
You know, I have noticed that I am idling higher. And when we had moderate weather a few days ago in middle of the cold (40s ish) my MPG went back up. Felt like she was running smoother too. Almost feels sluggish in the cold.
 

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ELVIS LIVES !
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Your motor will run a little richer (uses more gas to air) in cold weather to get you motor to optimum operating temp. And with your TB it is probably hurting your MPG. The TB allows more gas with less throttle, so the combo of the two may be what is going on. If it was somthing else your car would get bad MPG at all temps.
 

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Also most companies switch to a winter blend of gas witch for whatever reason generally shows lower MPG.
 

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Your motor will run a little richer (uses more gas to air) in cold weather to get you motor to optimum operating temp. And with your TB it is probably hurting your MPG. The TB allows more gas with less throttle, so the combo of the two may be what is going on. If it was somthing else your car would get bad MPG at all temps.
None of the above is correct

Tom
 

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I would check your o2 sensor with a scan tool and see what the trims are showing , if that checks out ok let me know and there are other things you can check that will cause poor MPG

The engine does not know it is colder out other then start up and when up to temp it sees cooler intake air temps but can fully adjuust to this if anything you should be seeing better performance and MPG

Tom
 

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^^^^^^I'm not sure if that's true either. From what I know about these systems, the computer uses intake air temps, and coolant temps, to adjust the A/F ratio for quite a while in very cold weather. Which means, you're running richer for much longer in cold weather, your idle speed will be higher for much longer, and your over-all MPG will suffer.

You'll get worse MPG in cold weather, than in warm weather. Seems normal to me...
 

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Discussion Starter · #10 ·
I would check your o2 sensor with a scan tool and see what the trims are showing , if that checks out ok let me know and there are other things you can check that will cause poor MPG

The engine does not know it is colder out other then start up and when up to temp it sees cooler intake air temps but can fully adjuust to this if anything you should be seeing better performance and MPG

Tom

I don't really have any way of doing that right now, or any time soon that I can think of. But if I do I will post my results or message you. I appreciate it.
 

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my car started this in the last few days too
 

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^^^^^^I'm not sure if that's true either. From what I know about these systems, the computer uses intake air temps, and coolant temps, to adjust the A/F ratio for quite a while in very cold weather. Which means, you're running richer for much longer in cold weather, your idle speed will be higher for much longer, and your over-all MPG will suffer.

You'll get worse MPG in cold weather, than in warm weather. Seems normal to me...
The AF on the Focus is adjusted by the o2 sensor targeting 14.7 AF and the ECU does this in closed loop, coolent temp stays the same in cold weather as hot , thurmostat sees to that and the IAT deals more with timing adding timing in cooler weather because with cooler weather the engine can stand more timing

LOL , Why would you get worse MPG in cooler weather ? your engine is more efficiant in cooler weather thats why it makes better HP/TQ at all RPM

Tom
 

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^^^ I've always thought the thing stays in open loop longer in cold weather, during the warm-up period. And I suspect the engine cools off faster with it's aluminum block.....so it goes back into open loop faster, when you make short trips.

I've always got about 10% worst MPG in the winter with other cars. My first tankful in cold weather with this '06 returned closer to 20% worse than in the summer. I didn't expect quite that much a drop.
 

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FUBARCUS
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Ok I'm confused. I agree with everyone else though. My truck I used to drive got terrible gas mileage in the winter like 12-13mpg but in summer I would get 20-23mpg between fill ups, so did my o2 sensors go bad in winter and then magically fix themselves for the warm weather?
 

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I always get 3-4 MPG less in the winter. In cold climates, I have heard that they formulate the fuel differently. I also suspect the car runs richer until it warms up, much like a choke does.
 

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I have gotten barely 140 miles to 3/4s of a tank this week.... The reason is being in lower gears to get through the snow. I rarely shifted past 2nd... So fun...
 

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Adam
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When air is cold its condense, therefor more air, so the engine adds more fuel. More fuel, more air = less mpg.
 
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