From your CEL issue, it sounds like the DPFE sensor, there is a sticky on this at the top Team Tech:

http://forums.focaljet.com/team-tech/474968-more-dpfe-sensor-information-updated-photos.html

If yours is bad, it could be causing your poor fuel mileage. You may also want to change the fuel filter if you have not done so already.

I am not sure where you are located, but keep in mind that winter blends of fuel decrease your fuel mileage, and your car uses a lot more fuel when the engine is cold. Short trips in cold weather = bad fuel mileage.

 

Yeaa the dpfe sensor I swapped that out twice for the CEL. This has been goin on for about 4 years already summer or winter. I live in MA so the mpg is pretty harsh during the winter. But I don't think I've ever gottin more then 20 mpg since I've had the car

 

I got 26.7mpg on my first tank with the car (only had the car a month now) and I had my foot in the throttle 70% of the time.

something is up.

 

Yeaa something has to be up. The car runs like a top. Its only got 29,000 miles

 

I have the same year and engine as the op and have the exact same problem. I get barely over 20mpg. Here is a thread I started last month.... http://forums.focaljet.com/welcome-jet/619209-2001-focus-getting-terrible-gas-mileage.html

I had planned on getting the spark plugs, wires, and fuel filter changed yesterday but I ended up using the money I set aside for something else. So for at least another month I have to deal with the poor mileage.

Now I am reading the op changed the plugs & wires and a few other things and still has the same problem which worries me that if I changed all that mine might not get better mileage either. However I never had the CEL come on in the one year I have owned the car so our mileage problems might be for different reasons. Any ideas or advice would be appreciated.

 

215 lol my last tank of gas lasted me a whole 150 miles

 

yea i just filled up 2 days ago and the tank before that lasted 187 miles. i just bought a fuel filter for it im gonna put that in within the next week or so. i swapped out the pcv valve whether it was good or not it was only a few bucks. i will update after i swap the fuel fiter and im hoping to see a change in the mpg

 

Plugs? Check! Wires? Check! Air Filter? Check! Fuel filter? Check! EGR valve? Check! DPFE? Check!

Have you checked...

...tire pressure?
...Mass Air Flow Sensor (MAFS)?
...O2 sensor?
...oil (is it 5w20?)?
...spark plug gap?
...transmission fluid (not that that'd change gas mileage, but a fresh start certainly can't hurt things)?
...octane of the gas you use, and whether it contains ethanol?

You don't have tires on there with some sort of freakishly high rolling resistance, or perhaps some size that might somehow adversely affect mileage, do you?

--Scott

 

i took a look at my MAFS and it was so clean that i could eat off of it lol my tire pressure is good. plus gap is correct. its got 5w-20 for oil. the o2 sensor im not sure of but if there was a problem with it wouldn't it throw on the CEL? also a friend of mine mentioned my coolant temp sensor giving false readings to my ecu so idk if that could be the problem...i would really love to fix this problem i love this car and i dont want to have to get rid of it, its basically still brand new! this is so aggravating..

 

215 miles you got is city mileage? highway mileage? what is your commute pattern? when i had a commute of 2 miles i would get around 195 miles per tank and a tank of gas would last me close to 1 month. That mileage was considered normal because the car was constantly warming up. I have a 01 zx3 manual. My best highway mileage was around 31mpg.

BTW i think a fuel filter change might make a little difference.

 

its a little bit of both. from my house to work is a little over 4 miles and i hop on the highway for like 2 min. but yea im hoping the fuel filter will help. the car sat for about 2 years so im thinkin that filter must be full of junk. also today i took a ride up to providence place mall which is about 20 miles from my house. i used basically a 1/4 tank of gas there and back...

 

Any chance of a clogged catalytic converter?

 

im hopeing its not the cat, again like the o2 sensor wouldnt it throw on the CEL?

 

.

 

wow any luck figuring out your problem yet? this is my 2003 zx5 2.0 zetec..... (60% highway 40% city driving-- 87octane at 5k above sea level)

 

Not necessarily. I had my OEM cat on my old ZX5 clog, and was wondering why it was robbed of power for a few weeks, no CEL, nothing. I thought it might be worth throwing out there.

 

ohh man i hope it isnt it, you think the cat would go with that low of miles?

 

Nah, not likely. Unless you have a shorty header or something, the cat is probably fine.

 

considering I got 195 miles per tank with a 2 mile commute, it seems pretty normal that you get 215 miles per tank with a 4 mile commute.. I used to live in upstate new york so weather wise we are similar. When i changed my fuel filter I increased mileage by around 10~20 miles per tank.

 

i get around 330 miles to a tank with the 2.0l z tec engine. it does seem to enjoy fuel. My firend has a peugeot 306 2.0l xsi and she gets 400+ with the same bhp? is the ford engine just really thursty or have i got a problem also?

 

I would say thats normal... short drives kill fuel mileage esp. in the winter....

When I was driving mine short distances (when I lived at home and was still in school) I would average 215-230 per tank yet I wouldnt let it get much under 1/4 tank... kinda anal about that...

Out on the highway... I could get closer to 300 if on a long trip...

Havnt had the car out for a long distance run since I did all the work to it... so not sure how I've effected fuel economy... we'll see.

When are you filling the tank btw? When the fuel light comes on or sooner? if you still have a little under 1/4 tank and your getting 200+ miles on the tank in such short drives... I'd say its normal...

Have you actually figured your mileage based on how much fuel you are using (fill it up... reset trip mileage... drive normally until your next fill up and divide your total mileage by how many gallons it takes to refill the tank)

Anyways... good luck
-AcId-

 

ive let my tank go till my gas light comes on and then pushed it a little more then fill up and reset the trip. and ive calculated 18.5-19.0 mpg a number of times

 

i jut filled up today. my last tank lasted 211 miles!!! wooooohoooooo, but still not that happy....

 

I just read something elsewhere about somebody getting bad gas mileage due to a fuel on its way out. There were some issues and recalls with fuel pumps on several model years from what I can remember. I know my fuel pump in 02 zx5 was replaced under warranty around 30K miles. Something else to consider but I wouldn't throw money at it unless you are sure.

 

I am getting 180-220 on a tank with mixed driving. I had a bad IAC and I thought that was causing it because of it staying at like 2k rpms all the time... but I replaced it a week later my cel comes on for the egr. I'm gonna go ahead and let the dealership fix it under warranty.

 

i accidentally switch from 5w30 to 10w30, (wife got the wrong weight didnt realize it till i put it in) My gas mileage stayed exactly the same. I get 300-315 mostly rural road driving. Not as good as it should be, i plan on opening up the exhaust and intake here shortly, i expect to see some improvement.

 

see its so weird how like one car can get 300+ miles to a tank but another car can get barely 220 out of a tank. im assuming it all has to do with the driver lol

 

It is all about driving style, and commute profile. Those, more than anything, will affect mileage. I see your location is MA - is your commute 4 miles inside the city of Boston? Lots of red lights? Stuck in traffic a lot? If the answer to those last two questions is yes, think about your idle time. Any time you spend idling in traffic is time that you're getting 0 mpg. Are you gunning it away from red lights? That doesn't help either.

I get mid-upper 20s here in VA in my Focus when I use it to commute - about 12 miles one way, nearly all 5th gear highway cruising, fairly small amount of time stuck in traffic, pretty much no lights. When my wife drives it for errands and short trips, mileage goes down - she's more aggressive away from the lights than I am, her trips are shorter, and she spends more time with the clutch partially engaged.