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New owner of a used 08 focus with 70k miles. The car runs great. My one issue is fuel efficiency, it gets between 22-26 mpg. I drive half city half highway. I never let the rpms exceed 3k and coast as much as possible. After searching the forum for answers i've replaced the fuel filter, spark plugs, air filter, cleaned MAF, topped off tires, changed oil and removed extra weight. Not sure what to try next.
 

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The usual questions at this point are.

A: How are you checking mileage?

B: Have you checked wheels for drag? (jack up & spin)
 

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A: Gas up till it clicks. Reset trip meter. Drive to 1/4 tank. Gas up till it clicks. Divide miles driven on trip meter by gallons on receipt

B: Not yet, i'll try that tonight.
 

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Cool, at least there's no question the numbers you're getting are ones that are useful (had to ask, not all use a good system to figure).

You aren't far off in mpg., about 3 mpg better is typical for my manual trans version. '08 is usually a little better, automatic is worse, averages out.

P.S. - here's a thread that's currently active again on mileage for your year:http://www.focusfanatics.com/forum/showthread.php?t=368458
 

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About what I get with half city half highway in my 2010. The car shines on pure highway miles with getting close to 30mpg, but I've got a lead foot when it comes to the 80MPH tollway we have in Austin.

--CDM
 

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Have you tried resetting the PCM?. With all the tuneup and cleaning work done it might need to relearn?. Disconnect the battery and wait an hour or short the positive batt CABLE to ground for 5 or so minutes then reconnect everything, take out out for a spin on the highway doing 55 to 65 mph for a good 10 or so miles to let it relearn then see how the gas mileage is?. its worth a shot?!...
 

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Do you still have the factory MAF? I ran into a problem a few years back with a non factory MAF. Any vacuum leaks? Aligment? Tire Pressures?

Scott
 

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Another thought i had is if your air filter has been replaced and the air box is buttoned down properly with no leaks, the potential for leaks could disturb the air flow characteristics to the MAF sensor and cause all sorts of issues with performance that just might compromise fuel efficiency despite appearing to run ok.
 

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My auto 2010 used to get 17-18 maybe 20 mpg on a good week all around mileage about 1/2 city and 1/2 hiway haven't checked after turbo and engine build. My 2012 with a dct I get 28 mpg combined or like 33-35 on a long trip. I drive hard maybe that's why. I've tried driving like a grandma and I just can't.
 

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My auto 2010 used to get 17-18 maybe 20 mpg on a good week all around mileage about 1/2 city and 1/2 hiway haven't checked after turbo and engine build. My 2012 with a dct I get 28 mpg combined or like 33-35 on a long trip. I drive hard maybe that's why. I've tried driving like a grandma and I just can't.

That is the truth right there, a huge portion of fuel economy issues people have can often be traced back to how they drive the vehicle. A good example i have seen is that when i was driving a different shared vehicle a while back i could easily get in excess of 1000km/tank (Average) when other people driving the same car would get as low as 700-800/tank (Average), the only variable that changed was the driver.

I can get around 32-35MPG out of my 02 focus (EPA revised combined is 25 (23 city/29 highway)), but that is only because of my driving habits, and i am willing to say it isn't easy.

Combined for your vehicle is listed at 28MPG, so the variance present isn't all that odd. What speed do you normally drive on highways?
 

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I float around 70 on the highway. Not sure if it has the OEM maf. I haven't checked for vacuum leaks, guess that's next on the list.
When I'm going 70 MPH on the highway depending on the winds and what direction they are going i get a minimum of 30 to 31 MPG to 32 to 37 MPG with a tailwind. Everything is stock in my engine compartment so you should in theory be getting close to that mileage.
 

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Not necessarily, remember his numbers were from combined usage (at highway speeds well cruising he might be getting these numbers exactly, remember he doesn't have a real-time display and has to go by tank to tank average) and admittedly, ford focus at city speeds are not that great on gas.

My focus loves highways, but when it comes to city driving, if i drove the same way alot of people do around here do in terms of aggressiveness, jackrabbit starts, hard acceleration, ect, i could end up in the low 20's for mpg (actually tried this to confirm the effectiveness of driving habits in low speed traffic, lowest average for city was below 20MPG*)

It is likely that everything is operating as intended, no point in wasting time and money chasing ghosts.


* trip recorded by a live data capture VIA the OBD computer, allowing the isolation of the city portion.
 

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Not necessarily, remember his numbers were from combined usage (at highway speeds well cruising he might be getting these numbers exactly, remember he doesn't have a real-time display and has to go by tank to tank average) and admittedly, ford focus at city speeds are not that great on gas. It is likely that everything is operating as intended, no point in wasting time and money chasing ghosts.
If your fat peddling in the city your mileage will go down the toilet Ive done it a few times and i was getting as low as 18mpg. But if you start off slow and get up to speed fairly quick afterwards and coast the rest of the way and to anticipated stops, i found the mileage goes way up in the 28 to 32 mpg range. Depends on the individual's driving habits..... and how long of stretches in the city you have between stops?.
I know bad pun .... But your mileage may vary......
 

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I could get a ScanGaugeE. $100 seems like nothing for everything it does. Code scanner & mpg meter, among other things. Thanks for all the suggestions btw.
 

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Well today my engine light came on. I scanned and got two codes, P0128 and P0113.
Okay, the P0128 code might be caused by the bad intake air temperature sensor problem you're seeing. If not, there is a TSB out for this, but they'll have to reprogram your PCM: http://www.automd.com/tsb/bulletin_b239456/ If you also have a delayed 3rd to 4th upshift, I'd recommend getting it?

Back to the P0113. Basically, the PCM supplies the sensor ~5V and if it gets back more than 4.6V from the sensor, it's maxed out and the car thinks it's -58*F outside. As you may know, cold air is dense and has more oxygen by volume, so the colder your car thinks it is, the more fuel it needs to use to stay stoichiometric. I'm not totally sure how this works when O2 sensors should pick up the lean/rich condition and adjust accordingly, but until those sensors get warm enough or if you're at WOT, I'm pretty sure the car uses an open-loop algorithm (ignore O2 sensor feedback). Is your exhaust black? Does the car accelerate poorly?

Anyway, if you PM me your email I can send you a PDF on diagnosing P0113 for the 2008 Focus SE.
 
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