2003 civic si hatch back gas mileage problems.

NYSpeed Automotive
1

Ive have the car for about a month now and Ive been noticing the gas mileage isnt anywhere close to where it should be for this car when I calculated it the past two weeks. The car is bone stock, doesnt leak or burn a drop of oil and was adult owned. I am the second owner. I only run 91 in the car, and it just had a fresh oil change and I drive it like a pussy (shifted above 3,000 rpms) maybe 2 times since ive owned it like all my cars.

It has a 13.2 gallon tank and this week I got 85 miles to a half tank, you do the math. its roughly 13 miles per gallon city when it should be getting 26 city and 30 on the highway.

The car runs and drives good besides it getting the gas mileage of a 4000lb pick up truck. It has no check engine lights or anything like that.

Ive never really had this problem before with any of my other cars.

What can I do? What do I even check?
any idea any help would greatly be appreciated!

here is a full list of all the specifications of the car
http://www.honda.com/newsandviews/article.aspx?id=20070606991

thanks,

Mike

2

check for gas leak?

3

its a possibility but I don’t think because I have never smelled gas or seen any fluids leaking anywhere under the car

4

change plugs, wires? see if it improves

5

o2 sensor? does the exhaust smell rich?

6

Did you fill the gas tank again or are you just judging that 1/2 is gone because the gauge says so?

The gauge might be off…

If you filled it up again and it really took 1/2 a tank I’d say check into gas leaks. I don’t know if bad plugs and a bad o2 would make a 30+ mpg car get ~10mpg lol.

7

You’re measuring wrong.

Fill your tank up to the top (until the nozzle clicks off) and reset your trip meter. Drive until the tank is at least down to 1/4, then refill the tank (again until the nozzle clicks off). Miles driven divided by gallons that fit back in = your real mpg.

You’ll probably find that you don’t have a problem.

8

^ o2 sensor can be on it’s way out and not be throwing a code yet. Or what Fry said.

9

Might do that next

not really smells normal lol. hell my lsvtec integra on a really rich base map got better mpg than this thing lol.

Thats what I did im not going by a half empty tank to 0, I filled it even a little above full after it clicked and it got 85 miles to the first half of the tank then filled it back up with another half tank of gas.

sometimes Ill drive the car a short distance maybe 5 miles and notice the meter moved a slight bit down.

But then one night I was in this broads drive way talking to her in my car and I left the car running in neutral for like 2.5 hrs to keep the heat on and the gas gauge didnt move at all. So its not making much sense to me.

10

id check the o2 sensor, they have a factory wideband which could really effect the gas mileage

11

hm ill have to check that then. I have a feeling its gonna be expensive as shit lol

12

best bet is autozone, they sell one for 160

13

thats not too bad, where could I even take it to test if mine is bad?

14

Unbolt it, put a spark plug non-fouler in then bolt it back into the non-fouler and see if that changes it at all.

15

put in a new one and see, if its not throwing a code it could just be because it hasnt gotten to the point where its so far out of its range to throw a code

or you could get kpro and that would be an easy way to see what that o2 sensor is doing,… then you can also get a tune to get better mileage and more hp while your at it

i was getting 34mpg highway with my built k24 so you should be able to get close to that when tuned

16

hm how much is kpro?