[boostedcx]

Hi all --

I bought my 2004 TSX in November of last year. It has about 120,000 miles. If I just drive to and from work (all stop and go) and some highway, I only get 13-17 miles per gallon, maybe 225 miles per tank. I've just been dealing with it because I don't have time to take it anywhere. This past week I took a 700 mile trip for work, and I got one full tank of highway miles only, and I got 530 miles! So, clearly the car is capable of getting better gas mileage. Anyone have any ideas on what would be causing such a huge difference?

Thanks

 

[SlapyoMomma]

Yupp. That's a Tsx for ya. There was a time when I averaged 16-18 now I'm doing 23-28. But that's because I drive more hwy now. Any cel's?

 

[boostedcx]

No check engine light. I use 91 octane, which is premium here.

 

[SlapyoMomma]

I use 93 and have a bad o2. Maybe you have a heavy foot. When I got bad mileage it was due to having my system weighing it down (which I still use) and my roof rack. It made it horrible.

 

[D Garage]

sounds like there is some kind of mechanical issue. The worst my gf ever got is 24 mpg which was all city driving and a heavy foot. Maybe see if there is an ecu reflash recall on it. O2 sensor or injector/ spark plug problem

 

[huludicidal]

17 in the city sounds completely normal. I have never heard or seen any lower though. I live in Boston and it's all extreme stop and go. When I'm on the freeway, I get about 27-31. I would be concerned about the <17mpg numbers. Are you calculating fuel economy correctly? You state some numbers about miles-per-tank but never state how many gallons you actually used.

 

[boostedcx]

I have a very light foot, I always shift below 3000rpm. I do not have a stereo or a roofrack. My "stop-and-go" is nothing like Boston driving, I live in Maine so the traffic is not a problem. I calculate my mpg by filling up and dividing total miles driven by gallons pumped. I got 14.2 on my most recent city tank before the 35+mpg one.

 

[huludicidal]

I think your concern is warranted. I don't typically drive around town with regard to fuel economy. In fact my wife often comments on my heavy foot. I am looking at my fuel consumption history (I log all my numbers) and my worst ever was 17.31mpg on 93 octane. This could be a faulty oxygen sensor or haywire ecu. If you can, I would datalog air/fuel mixture to test any hypotheses. It sounds like around town you run pretty rich. How fast do you drive on the freeway? I drove from the south jersey shore back to Boston with the cruise set at 70 (3000rpm) and got 31 mpg, my best ever.

 

[din9lebeRrY]

I have a very light foot, I always shift below 3000rpm. I do not have a stereo or a roofrack. My "stop-and-go" is nothing like Boston driving, I live in Maine so the traffic is not a problem. I calculate my mpg by filling up and dividing total miles driven by gallons pumped. I got 14.2 on my most recent city tank before the 35+mpg one.

how much throttle you put (how quickly you get to 3000 rpms) is more directly related to fuel economy than actually which part of the power band you are shifting at.

I used to be like you (btw I live in NYC, city = traffic traffic, not like how some people state 23 mpg in the city streets of Iowa lol) and used to religiously shift at 3000 rpms when I first got the car. In NYC traffic, that meant a lot of throttle to move from a get go (no low end TQ Honda) so people wouldn't honk. And by shifting so early, it would put require more throttle to move up the powerband in the next gear, till eventually when it started to move, stop time. I used to get 16-17mpg this way.

Now I shift more in between 3500-4000rpms, it keeps me above in a good portion of the powerband in the next gear so I can keep a light foot, be moving at traffic speeds and get good mpg.

Strictly city I can average around 19.5 this method...I often average around 24 mpg but that is usually 50/50 city highway. I'm sure traffic in Maine isn't as bad as rush hour NYC traffic :laugh:

 

[tsxklap]

3 quick tips:

1) in the city, try to coast when coming up to red lights. it can make a difference.

2) use a chevron techron fuel cleaner once every 10k miles

3) disconnect and then reconnect the negative terminal of your battery so the car can re-learn your driving habits and re-formulate its air/fuel mixture.

ps: and dont judge my mpg avg in my sig yet. thats when i was running my winter set up. im barely over a half a tank currently and i almost have 300 miles recorded. and i am by no means a eco-driver (80-85mph on the highways)

 

[boostedcx]

Well, my car is automatic, so I dont completely control the shifting. I typically accellerate as slowly as possible. No lead foot for me, thats what my Civic is for.

I always coast when possible, I am very gentle on the throttle. I guess I will try the injector cleaner and battery terminal idea. Anyone else have any tips?

 

[Hawkins21]

wow, i dont think i have ever gotten less than 24 mpg in my suburban area. just take your foot off the pedal. and not just the gas, hitting the brakes hard can and will cause the car to downshift to use the engine to help slow you down. pick a speed and drive it, 40 mph is the absolute perfect speed for mpg's. and anything over 55 is a waste of fuel. if you look ahead and see the light is red, stop accelerating, you dont have to hurry up and brake.

i like to drive spirited too but you have to pick your spots.

 

[boostedcx]

Please read my posts, I drive like a grandmother. I use the least amount of fuel as possible. The bad mileage is not because of my driving habits. I've driven my TSX "spirited" maybe once, which was the day I bought it.

 

[JTrix215]

Have you changed your spark plugs at all?

 

[boostedcx]

So far I have reset the ECU, and used injector cleaner. I ordered a set of IZFR6K-11 plugs off of eBay last night, they should be here in a few days.

 

[LeeMaster]

I never average 20 mpg unless its winter due to the usual slow stop and go traffic on the highway and cities. There is no solution, this car was made with terrible city gas mileage, if you can somehow reduce the weight by 300-500 lbs then maybe you will see a huge difference.

 

[D Garage]

I'm kinda surprised you guys are getting that bad of gas mileage. my gf's 06 averages 26-27 all city driving and 32-34 all highway. my 09 gets about 28-30 all city. Havent driven it enough to tell what kind of highway mileage i get. I think that's pretty decent for a sporty nicely equipped 4 door.