danmm7

iTrader: (1)

Car is 2004 TSX, AT with Navi with 60k miles.

On the last tank of gas, with 80% highway driving the car needed a refuel only after 270-280 miles. The on board computed showed avg. of 22 MPG.
There are no check engine or any other lights on. Car "feels" and drives normal.
Driving style has NOT changed at all....since my wife is the only person driving it.
She always gets at least 26MPG or better. When i drove it, i got 24MPG or better.
This time, just by looking at the gas gauge, i can tell that gas goes much faster.

What could be the reason for this drop in MPG?? Car is well maintained. Good brakes, fresh fluids, new tires, premium gas, no leaks - we keep up with the maintenance.

What should i look at? Is it worth it to plug it to an OBD II scanner even if there is no check engine light on?
Could it be just a tank of "bad gas"?
Has anyone had this issue happen to him/her?

Thanks!

LuvMyTSX

Are these new tires the OEM Michelins or another tire? Some tires can lower mpg slightly. This happened with my Bridgestones.

smock9

I've also noticed lower gas mileage lately. There have been a few conversations about the effect of Winter Gas

I'm not sure if thats the only cause but I'm as curious as you are.

danmm7

iTrader: (1)

The tires i have a Yokohama Avid V4s. They've been on the car for more than 5k miles. They did NOT affect the MPG at all when i installed them.

jlukja

Have you checked your tire pressure?

I've also had reduced fuel economy over the last 2 tankfulls. from 27mpg to 23.5mpg. Weird.

LuvMyTSX

Well, a lot of things can lower mpg. Yours isn't all that significant so I wouldn't be concerned just yet as long as it's driving normally. Maybe you idled it a little longer, sat in traffic a little longer, drove it harder a couple times, etc. There are just so many variables that could lower the mileage, including colder temps and winter gas, as mentioned above.

jmathew34

it's the gas troll

n3ok318

iTrader: (1)

when i got my new tires, mpg dropped significantly.

loulinjai

what tires were those?

DurgyNess

Check air filter, when is the last time you've had an oil change? check oil.

Both of those decrease mpg

Tsx536

I hate that guy!

Jeff The Pianist

Maybe you've gained some weight?

haha jk!

danmm7

iTrader: (1)

Air filter is 15k miles or less old. I'm about to change it now at 60k.
Oil is almost 5k miles old - also to be changed this weekend. I use Mobil 1 Synthetic.

As you can tell, both of them are not that old.

DurgyNess

Check mpg after you change those 2 , Oil change will increase mpg for sure and since you've only dropped 2 miles per gallon you may regain it after this

jlukja

to further my thoughts here... I received a Costco membership for Christmas so I've filled up at Costco the last 2 times instead of where I used to buy my gas. Also, I've been using my climate control system on "Auto" much more in the past month because its been colder and I wanted to keep the windows from fogging. These two seem like the likely candidates for my mileage dropping.

Have you made any changes like this?

rb1

My car drops 2-3 mpg just because the temperature drops below 40F versus being 60 or above, even with the same gas in the tank...

(If you're keeping your car maintained on schedule, an oil change isn't going to make a perceptible difference unless you do something like switch to synthetic, and even then it will be marginal...)

Osmodious

Some of it might depend on where you live...in the Northeast (and Northwest, I believe), we get that wonderful 'oxygenated' gas, which sucks. You get poorer mileage AND performance for the same, or greater, cost...whoopee!

Also, note that Sunoco is now using a high percentage of ethanol in ALL of their fuel, again most specifically in the Northeast. Ethanol provides higher knock resistance (octane rating) but has less energy by volume compared to gasoline, so you will ultimately get poorer gas mileage (probably less power, too).

I have noted a 2.5-3mpg difference when using Sunoco fuel compared to Exxon or Shell.
Os.

hiptech

If all the usual suspects have been eliminated, air and fuel filters, clogged fuel injectors, etc. I'd be looking at a possibly defective sensor, maybe the O2 sensor?

Try picking up a couple of bottles of fuel injector cleaner first and see if that helps. If not, move on the sensors.

mk1021

Hi! My husband and I also have a 2004 TSX, but it's a 6 speed manual. We are having the exact same problem. I seriously thought there might be a hole in the gas tank because suddenly it is awful on gas! Have you found any info about this problem? If so please let me know. Thanks for your time! Glad it is not just us having this issue~

cls1000

i've never gotten over 20 in mine, but my drive is only 4 miles and i have 16 stops on the 4 mile drive, so i prob. can't get much better, i would be happy with that!

tofumonzter

since we're on the topic.

is 320-380miles(mostly highway) normal from a full tank. 6speed.

LukeaTron

Assuming you put 13 gallons when you filled up, that's 24 - 29 mpg. Pretty much what should be expected for those conditions.

I've gotten just shy of 500 miles out of a tank on long highway trips. I forget how much exactly I put in but when I crunched the numbers it was a little under 38 mpg. This car just sips at gas properly coaxed to do so.

TS_eXpeed

That running dude always cracks me up.

danmm7

iTrader: (1)

Here is an update....

After 2-3 tanks of gas, oil change, new air filter and fuel injector cleaner - gas mileage is back to normal! We are getting 23-24MPG on mostly city driving and 28-29MPG on the freeway doing 75-80mph. It's been good for the last 4 weeks.

Not sure if the fresh oil/air filter were the reason for the improvement or it's due to better gas from the pump.

jjs_tsx

Hi there, I had a similar problem twice so far with my 2006 TSX, the first time I notice it within 3 or 4 days and I track it down to a tire with low pressure due to a nail on it, after fixing the tire all went well for several month until about 5 weeks ago when I notice about a 20% decrease on fuel consumption with no apparent reason, it went like that for about 3 weeks when it just got back to normal without me doing anything other than checking tires and the usual checks (It had being service about a month earlier). I notice the change after putting gas at a Costco gas station in Seattle, it was not the first time I fill up there, but the first time this happened to me, I think either that was a bad batch of gasoline for whatever reason, or I had some dirt on a filter that finally dissolved or something, its being 2 weeks with excellent gas mileage as it usually is.
A mystery as I'm the only one that drives my car and I'm pretty regular on my driving style and the places I go to in town.

iamgoinbiking

All, I don't know what the conclusion of this thread was. I stumbled upon this while trying to figure out why my TSX's fuel economy dropped. I just replaced 2 of the OEM Michelins with Yokohama avid 4S. That seems to the culprit!!

nj2pa2nc

the gas mileage went down on my 06 tsx when I replaced the OEM Michelins at 74,000 miles with Yokohama avid 4 s tires. Not happy with them-noisey, lose traction easy on wet roads, etc.

gasser

bought my car already with these on, don't like them at all! Noisy, like you said and completely useless when it comes to driving in wet dirty conditions =/

zlata23

i just bought my '04 tsx about 2 months ago @ 84,000 km. did an oil change as soon as i bought it with pennzoil platinum full synthetic and tire rotation/alignment. i've also been using 91 octane fuel. but i'm only getting about 400km for every tank! (60%city driving) is that normal? it feels like its using gas too fast...

i used to own a z24 prior so i dont know if its that comparable but even my cavalier got much more gas mileage then this one!

should i do a tuneup? or could there be a bigger problem here?

thanks for any advice!! ** I do love my TSX tho, she's a beauty!**

Simba91102

You don't mention where you're located, but I'm guessing it's winter there (like under 40 degrees), and I think you're in for a pleasant surprise when the weather gets warmer. This is an older thread (check the date on the first post) and in my opinion, mostly full of urban myth and wishful thinking. About the only thing that's going to increase your mileage noticeably is for the ambient temperature to go up allot, or dramatically change the way you drive the car (and if you're already careful, that won't help either). Oil changes, air filters, various tires...... in my experience (and opinion), will make little to no difference (and to those that think it does or could..... well, you're the people that keep advertisers and marketers humming along). If your local fuel has recently been spiked with ethanol (another special get rich give away from the federal government for the corn farmers at the expense of the rest of us), that could be part of it too. The so-called "California" gas (that those of us in New England have been suffering with for a few years now) was good for a 5%-10% drop all by itself. But I digress. Wait for spring and summer and you should see your mileage improve.

zlata23

i live on the west coast of canada, and we've actually had quite the mild winter (you could probably see all about it on the net with how our olympic mountains are lacking snow :P ) so i didnt factor that in with my gas consumption

i guess i'll keep an eye on it as the summer approaches...

salmart3129

I have a 2004 Milano Red TSX that I just got a month ago. 69,000 miles and have had some very different MPG from it. I think mine are from cheap tires the dealer installed and I didn't pick up on until reading this thread. They are ZR Raptor by Riken Tires. I will keep them until they wear out...I expect fairly soon...
On the gas milage side...Costco gas has methenol in it up to 10% and I have avoided it because it does reduce gas milage in my other car..2002 Accord EX. I have been running 93 octane in my 2004 TSX and have found gas milage vary...from 25 to 28 mpg with my foot out of it. Most of the driving I do is 38 miles one way to work and mostly freeway in Mighigan. The cold does seem to make a difference to...less mileage. I am glad to not be the only one out there that has seen shifts on daily commute gas mileage.

Simba91102

I don't want to start a pissing about tire choice and gas mileage, but my advice is to not expect too much difference in your mileage from a tire change. I'm not as old as you are, but I'm pretty sure that I'm older that most of the participants here, and in my experience (with many different cars and numerous different tires), any possible improvement (or decline) can be better attributed to other causes. Ambient temperature (the biggest factor), idle time (either in an attempt to "warm it up", and/or sitting in traffic), a different city/highway mix, and many more reasons. If you're unhappy with the tires on the car, by all means replace them. But I think doing it to try and pick up an mpg or two would be a waste of money. If you have a choice of gas (with or without ethanol) you're lucky. It's all comes with the 10% dry gas (ethanol) here in Mass. You evidently already know that gasoline without it will return better mileage. I'm quite confident the you'll see a noticeable improvement in mileage when the warmer weather returns.

Shorei

I have the Avids as well.They stop better than the OEM Michelins according to tirerack tests and handle about as well, better in the rain. They last so I won't be improving them for a while, unfortunately.
They are,however a pound or 2 heavier than the Michelins (Bridgestone tires are several pounds heavier) which can affect the mileage. I don't know what the stock wheels weigh, but I bet lighter ones would improve acceleration and mileage.
My mileage dropped when Florida went all ethanol. It dropped after the tire change as well. I am taliking about interstate at night with hardly any traffic with cruise and no A/C. It got better after a tank with BKG fuel injection cleaner though.
Re ethanol - Now, STOP AND THINK a bit here.
If ethanol gets you 10 - 20% less gas mileage and the gas is up to10% ethanol what can possibly be the benefit environmentally or conservation??? One burns the same or more gasoline with ethanol than without so known is conserved, hence the same or more pollution as well, only everyone is buying more fuel at the pump, spending more. Repealethanol as it isn't helping and some engines (especially small and outboard) get damaged by it..

nj2pa2nc

additional info:
we had the original tires on our tsx from 11/06-5/09-driving on numerous roads, different driving conditions, etc. The gas at the gas stations we use in NC does not contain 10% ethanol. We switched our tires-gas mileage went down-end of story.

Shorei

NC does not have ethanol? Not all stations get it at the same time when the conversions happen. Do you always look at the pump for the tiny little sign re ethanol?

nj2pa2nc

Have been using this gas station since moving to NC over 4 years ago-no ethanol-no sign and never has been one,. The gas station I use in Fredricksburg Va and also Toms River NJ do have the 10% ethanol sign so I do know what they look like