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So i recently received my first car beginning of Jan. after months of work and proving myself worthy, an 04 Civic LX...r/s title :[ passenger side front corner/wheelwell-region accident i guess, my dad bought it without consulting me, but hey...its a car.

Anywhooo onto the topic: over the last 5 tanks i have noticed that its only going an average of ~270/~21 miles tank/gallon... thats mostly highway miles and mostly not stop and go traffic. according to the site below they got an average of 27.32 mpg on a year of testing. do i have problems? if so, any ways to go about fixing/improving it?


sorry for such a long first post guys


http://www.optimizedliving.com/2005/...-lx-automatic/

 
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MPG's has to do with driving style for the most part. Also in the winter there are additives in the gas that kill MPG's.

 
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i would say i drive with a light right foot. my mom had my car for a week and had the same results. the additives though...i guess that could be it. will have to wait a few months to see how it goes then. thanks :]

 
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What RPM's does it idle at?

 
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it seems to fluctuate from ~800 - sometimes a lil over 1000

 
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wait until summer to know for sure, and measure driving all highway miles.

 
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sounds like something is wrong to me. just saying.

 
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well if it was in an accident, first thing to do is check the alignment. maybe it was never fixed properly and wheels arent completely pointing straight ahead.

 
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You might also check the brakes to be sure none of them are sticking. If you did not have a mechanic check the car before you bought it, checking the brakes will also give you an idea how long before they will need service.
I would also check the air filter since that is easy to do.

 
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alignment seems to be fine, but then again what do i know? i can take my hands off the wheel for a while and it'll keep straight though

 
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i wouldnt rely on just that, you could still have the toe a bit off. esp if its been over a year, its a good idea to have it checked out anyway. you could also ask the shop to spin the wheels while its up on the lift for alignment, see if there is any brake drag as mentioned.

 
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I have a 2001 civic 4dr LX AT with ~82,000 miles. The car still runs great and can still return in average 35 mpg (winter: 32-34; summer: 36-38) with city/highway mixed driving. Consider fuel consumption is a health indicator of your mechine. If mpg is low your car is running inefficently. When you see mpg goes down, first be sure to check

- air filter (very important)
- spark plugs
- fuel filter
- tire pressure (stock recom. pressure is good enough)

Always calculate your milage by filling up your tank in full, record your trip meter reading and reset it.
Alignment has nothing to do with mileage.
About driving style: I think the effect is minor. My friend drove my civic many times. He has a lead foot and I did not see any difference in mpg.
Oh, one more thing, you don't need to check PCV valve as this gen. does not have it.
For your reference, here are the mpgs of my cars:

- 2009 Mazda 3 5dr AT: 28-30mpg
- 2001 civic LX 4dr AT: ~35mpg
- 1998 civic LX 4dr AT: ~30-32mpg
- 1988 accord LXI 3dr AT: 28-32mpg


Other comments: In winter gas additives such as MTBE may lower your gas mileage by a small amount, but we get lower mpg in winter times mainly because of cold starts. Starting and warming up an engine in cold weather consumes more fuel. But in regions like SF Bay Area (where I live) this problem is minor.

 
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I would like to clarify a few things.

There is little mileage difference between winter and summer blend gasoline. Winter blend gasoline has a higher vapor pressure, which means it evaporates more easily in the colder winter temps. Summer gasoline has a lower vapor pressure because the warmer temps encourage evaporation and older cars had an issue with vapor lock.

What I am saying is that while there are differences in the fuel, their effect on mileage is minimal but other differences due to temperature can be large. Gasoline has to be vaporized to burn. As mentioned, a winter blend evaporates more easily but it still doesn't evaporate completely. A cold engine will still require additional fuel to achieve the necessary fuel to air ratio. Modern engines with port fuel injection do a much better job vaporizing fuel and inject it closer to the cylinder but until the intake manifold, valves and cylinders are up to operating temperature extra fuel is required.
Another factor with temperature is all the lubricants in the car are thicker. If 20 weight oil improves mileage over 30 weight at operating temperature, take a look at a viscosity chart and you will see that cold oil is many times thicker. You also have to remember that there is transmission fluid and all the grease in bearings that is also thicker.
I currently drive 32 miles each way to work with about 27 miles of it highway. I see a drop of about 4 mpg in the winter. At my previous job I drove about 12 miles each way and saw aboout a 10 mpg drop in winter. My point is that it can take a long distance at operating temperature to offset the warmup period. Factors such as outside temperature, inside parking, etc. all come into play.
To answer the original question, for now I would check the things that you can do yourself (brakes, air filter) and start keeping track of your mileage. If your mileage does not improve with warmer weather then you can look at replacing maintanence items like plugs and O2 sensors but at least you will know it needed them.

 
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You sir are dumb. The fuel filter is located in the fuel tank with the fuel pump so the chance's of it getting clogged and causing this problem..... Not very high, in fact it would cause other problems like the car dieing or stumbling.

Alignment does help with MPG. Think of it this way depending on what is wrong with his alignment he could have MORE contact on the surface on the ground causing more drag.

Your driving style is also important. He's an example..... Go out and drive your car normal with our getting on the throttle much at all test your MPG then. then fill it up and go wide open throttle all the time and again record you MPG. you'll see a much difference because what happens when you open your throttle plate up???? That's right more gas goes though the injectors and into you cylinders for a correct A/F ratio! OMG!!!!

Also most Cars have PCV Valves...... Just look at your valve cover and you'll see this awesome little hose coming off of it going to your intake! OH WOW where did that come from!

Also of course starting and warming your car up in cold weather use's more fuel..... It takes longer for the wideband O2 sensor (d17 2004-2005) or the normal O2 sensor in this case, to warm up. If your O2 sensor is cold and isn't reading then you ECU will run the motor rich to prevent knocking and such. When your O2 sensor actually reads the correct A/F ratio and the ECU recieve's the correct voltage it will go into closed loop and actually run the car NORMAL. I say this part again CLOSED LOOP.

If anything driving in cold weather would allow NA cars to gain more power and have a better compression due to the colder more dense air that you have filling your valves and into your engine. Please know what you are talking about before you post garbage on this guys topic. He's actually trying to find out information.....

-Chris

 
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You are correct, but for those that are interested, I would point out that there is a theoretical and practical difference. In theory, the colder the air the better. As you pointed out cold air is denser and more air will fill the combustion chamber which increases efficiency. From a practical standpoint, you have to vaporize the fuel so if the air is too cold you have to add extra fuel and mileage drops. I would think that engine design would influence the point. A carburated engine with long intake runners would be different from port fuel injection which would be different from direct injection.
Many stock intake systems on cars draw cold air from behind the headlight or something like that but they also have a valve that allows them to pull preheated air in cold weather. This allows the engine to warm up faster but also allows them to mix cold and warm air if the outside temperature is too cold.

 
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True but I got my point across = P. These cars have hoses that run into the thottle body that heats up the air a bit. (located next to the AIC.) But I think alot of this goes in with what they where saying about the Gas enrichment for "winter gas"

 
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altho, the throttle body heater hoses are really only to heat the IAC valve so it can adjust the idle speed. fast air moving thru such a tiny heated area will have almost no temp change (maybe 0.1 degree).

 
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you need to be checking things like PCV(which is on the back of the engine, not on valve cover). air filter, spark plugs and other maintanence items. there is no fuel filter on this car, and minimum u should be getting 32 mpg, even city. i get 28 mpg, and thats boosted at 9psi. my 07 si gets 27 mpg, at 11:1 compression and a bigger motor. check tire pressure, if u have any noises liek grumbling or the like u need to note it. u probably need to reset fuel mixture as well, pull ur battery for20 minutes, and reset all the parameters in the ecu. then give it a go, and keep an eye on ur mileage from there on out.

and unless it comes to lighting, dont listen to gearbox, hes a bser for life

 
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you need to be checking things like PCV(which is on the back of the engine, not on valve cover). air filter, spark plugs and other maintanence items. there is no fuel filter on this car, and minimum u should be getting 32 mpg, even city. i get 28 mpg, and thats boosted at 9psi. my 07 si gets 27 mpg, at 11:1 compression and a bigger motor. check tire pressure, if u have any noises liek grumbling or the like u need to note it. u probably need to reset fuel mixture as well, pull ur battery for20 minutes, and reset all the parameters in the ecu. then give it a go, and keep an eye on ur mileage from there on out.

and unless it comes to lighting, dont listen to gearbox, hes a bser for life

 
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Actually there is a fuel filter but it's more like a fuel strainer which is located on the pump (inside of the tank) It's a "Life time" filter from Honda. I've had a look at mine when I change the fuel pump.

 
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its a screen, not a filter, and is not "serviceable"

 
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According to Honda it's a filter and it is "serviceable" in the way that if it's clogged you can "clean" it.

 
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ive known a couple people that had to replace it due to low fuel pressure around 80k miles, but you will usually feel it when the car doesnt accelerate as well. it does essentially act as a filter, otherwise junk could easily get caught in the injectors. advance auto sells the filters for maybe $5. at least they gave us a lifetime pcv thats metal so you can just clean it off and reuse it.

 
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if anyone is interested in changing it, boosted2k2 did a diy on it:

https://www.civicforums.com/forums/1...placement.html

 
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see the thing at the bottom of figure one? That's the fuel pump with Honda's "Fuel Filter" If you insist that it still doesn't have one I can always call the dealership and get you a part number. Either way it is what it is and if they call it a filter then I guess it's a filter.

 
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Well time to hop on back to my thread haha o.O

Anyways...I'm going to do the plugs this week to see how that goes. I do have a rough idle which people have been telling me can be fixed with new plugs. I'll see if it helps the MPG any.

 
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notice they dont list a part for it.... hmmmm

 
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P/N 368420 - Honda Fuel Filter (about $30)

 
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First, It's not really an arguement. I presented the facts and showed you proof. Also I don't give a **** if you an ASE mechanic or not, that doesn't prove anything on the subject matter. Your mechanical skills would not help any way to determain whether or not it was a fuel filter or not. Any one can pick up a phone or READ and find out that it is still considered a filter. Just think about a regular fuel filter it works the same way right? Strains out the fuel before getting to the engine. Also if it's so worthless then you haven't really done much to make it better. I mean you've been on this forum for three years and I bet you haven't done one thing to change it. I don't claim to know more then a ASE mechanic but I DO claim to have common sense and the ablility to read. Please don't display your self as an over grown monkey next time and have a normal conversation like the rest of us humans. What ever you have against Gearbox you need to keep that to your self or PM him about that. This site isn't about listening to you cry and bitch about how you don't like him. If you hear to offer your two sense then do so but don't be dumb about it and bash on everyone.... Unless of course someone provides Totally wrong information that is way off. But really relax and take it easy and if your going to leave the forum by all means just do so quitely.

-Chris

 
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i have a 2002 si-g (usa ex) coupe and my fuel economy has always been between 24-29MPG even when the car was brand new. the best i'm able to get is 32MPG when doing all freeway driving at around 70MPH. i've tried lots of things but fuel economy never gets any better. anyone have any ideas? the people that average over 33MPG in the city, do you guys drive over any hills? there are hills in my city but i don't consider them to be extreme. i'll probably change out my spark plugs soon (75kmiles) but i don't think that'll improve much since fuel economy wasn't any better when the car was new.

background info:

1) note that in canada the sale of gasoline is based on energy content at 15 degrees celsius so the actual volume received is not what's shown on the pump

2) the engine has never had any mechanical problems and the car always passes aircare (smog testing).

3) i've tried driving very gentle (letting the tranny shift at 2500rpm) and fuel economy still didn't change much.

4) i generally don't use the a/c, but even when i do, fuel economy doesn't change that much.

5) i keep my 195-60-15 tires at 30-33psi.

6) i;ve tried logging sensor data using an obdii scanner but didn't notice anything that would cause my fuel economy to suck

7) changing my air filter didn't make any noticeable difference in fuel economy.