G0tSchnitzel?

Before I get into it I want u to know that yes I googled for a while, just want some input on what I could possibly be missing.

I own a 2002 Honda civic si and it has 110,000 miles on it. Over the past couple of months I have noticed my fuel economy has significantly dropped and it is killing my wallet as I'm having to refill almost every 4 days. All regular maintenance has been done to my car including: regular oil changes, new spar plugs, valve adjustment, cleaning of the injectors etc. my question is what could be causing this drop in fuel economy? I have looked into changing the fuel filter but I have been told the filter on my car should withstand the life of the car and it is probably not the issue. Could it be the fuel pump itself? Upon start up of the car I hear the pump prime just fine. I also don't smell any gas around the car so I dont think I have a gas leak. Any help would b greatly appreciated. Thanks in advance.

poeticfinesse21

Well all the little things add up. Is your car completely stock and if not, what modifications do you have? What brand and weight oil are you using? What spark plugs did you use? Do your tires have a decent amount of tread and are they inflated to spec? I believe it's 30 psi but I fill mine to 35 psi all around. Have you changed your trans fluid? How aggressively do you drive? Do you do mostly city or highway driving? And lastly, have you been keeping accurate track of your MPG? If yes, what is your exact MPG, before and after? I get roughly 23 MPG city driving and roughly 28 MPG on the highway, maybe more.

G0tSchnitzel?

Thanxs for ur response, well yes my car is pretty much stock other than a Sri nd catback exhaust. I change my oil with Mobil 1 synthetic 5w30 weight and a Bosch oil filter. The spark plugs were ngk iridiums. The last tranny oil change I did was at about 95k. Umm I just rotate my tired 2 weeks ago and I must admit the rears are at about 60% tread while the fronts are about 75% I slacked on my last rotation. I always leave the psi at 35 nd I checked it yesterday. I kno the tires have a little to do with it but I used to get 26 city and about 29 mpg highway. The last fill up I checked I was at about 20 city 25 highway nd I do mostly highway miles front work nd back. I don't get on it very much anymore.

poeticfinesse21

Try changing your trans fluid again, you really should do it every 15,000 miles. Also try matching a mobile-1 filter with your oil or a K&N filter with some castrol 5w30 synthetic. Tires shouldn't be causing a problem unless you're running winter tires in the summer or vice versa. If it was only one fill up when you noticed your MPG's go down then don't worry about it so much. Anything and everything could affect it, the weather, extra weight in the car, getting gas from a different place than you usually do. Keep track of it and if it doesn't go back to normal I would also suggest looking at your suspension components. Maybe it's time for an alignment.

G0tSchnitzel?

Yea its been right around 20 for the last couple months. But thanks for your suggestions, my car does need an alignment as its pulling to the right a little bit. I'll change the tranny fluid this weekend see if it helps. THanks again for your help.

G0tSchnitzel?

Yea its been right around 20 for the last couple months. But thanks for your suggestions, my car does need an alignment as its pulling to the right a little bit. I'll change the tranny fluid this weekend see if it helps. THanks again for your help.

92NoTeC

Did you replace the o2 sensor? Mine went out around 100k...