Hey guys,
I have a 2000 civic lx sedan, which gets 240 miles to a tank which is 10.9 gallons of gas (every time i fill it). thats literally 22mpg. factory says it should be getting around 27mpg in the city.
Now i have a question, i have a CEL which is p0505 idle air control valve malfunction. could that be causing the problem?
i always drive windows down a/c off, but still get just 22mpg.
i do drive the car pretty hard, usually its revving to like 4 or 5k, and i accelerate kind of fast most of the time. <-- i know that will lower my mpg, but should it really lower it that much?
any input would be nice. maybe i have some kind of exhaust leak? who knows, can somebody help me

 

Now obviously the windows won't drag your mpg down that far but windows open is worse then A/C it causes drag. Clean your IACV, check the FAQ for that if you need help. Drive the car RIDICULOUSLY soft for a day. Like literally shift between 1500-2000rpms EVERY GEAR. and keep the car in 5th all the way to your destination(If possible). See if it brings you're mpg.

 

Of course it will...but whats pratical about that? If it is suppose to get 27mpg, then something is causing it to suffer. The fix is not driving like you described.

 

You are either very uneducated or trolling. Driving the car hard and shifting at 5-6k with dramatically drop your mpg. from 27-22 that is completely possible.

 

Well i know for sure that revving that high every time is very costly for gas, but losing 5 miles to a gallon seems a bit extreme for just that. Ive gone days where i just drive very softly and what not, but seems as though every time i go to fill up, im at or around 240 miles. im thinking something is going on internal as well

 

Yeah something internally is going wrong. But the little factors do add up to mpg loss. Windows down, driving it hard, i'm guessing cheap 89 unleaded gas?

 

Driving it hard will cause the MPG to drop, especially depending on how hard, and how often you drive your car like that. Best bet is to clean the IACV, let the car warm up before driving it, and then drive it normally... with out being hard on it. Let us know how it turns out for you.

Any other CEL codes pulling up when you check it out?

 

Wierd...when I say it Im uneducated or trolling






Here in the northwest cheap gas is 87 oct....in cali is your cheapest 89?

 

Clean the IACV, do an ignition system tune up, replace the fuel filter, and drive more like grandpa.

 

It is often overlooked, but have you recently had/checked your alignment? I did a rear disk conversion recently so my alignment was way out of wack, I dropped from consistent 30+mpg shifting at 5k-6k to about 15mpg. Three days of driving, I was out like $60 in gas when that should last me at least more than a week and a half, even with lots of commuting. I could visually see my gas gauge dropping quickly just from work to home (80 mile commute round trip) Got an alignment, my mpg is back up again to 31mpg. I knew alignment could affect mpg a bit but I never thought it could that much. Just a thought.

 

+1

 

was having the same problem....i just had to change my oil.

 

^ yeah sure

 

+1

If this doesn't fix your problem you have deeper issues to consider.

 

hahah. Maybe if the OP was running gear oil.

 

No, no other codes were coming up. just the idle air control valve.
the alightment issue seems like it could be possible too, cause my car does particularly like pulling to the right quit a lot. ill definitely get that checked out.
so im guessing from here its just cleaning the IACV and seeing if driving better after that will make a difference, if not, i guess ill check the fuel filter and go from there. Thanks guys, hopefully its nothing deeper than that
you guys think tires could make the difference too? my tires are basically shaved lol, im getting new ones soon. could low tread tires cause a little issue?

 

Alignment can really mess up your MPG. It can even make your tires wear bad. And replace fuel filter and do a tune up