Help gas mileage terrible by the day
 

My 2015 fit now has 28000 miles on it and I been noticing my mileage has been going down slowly each day. A full tank would give me about 200-225 and my avg on my gauge shows 30mpg and now its 27mpg after 93miles driven on a full tank. I will be changing my CVT fluid and oil change this weekend but anyone else have this issue? Any tips on what I should do? I get top tier gas and dump a bottle of chevron fuel system cleaner every 9k miles when I change my oil. I did have a few times check engine light turn on and believe it was related to the fuel cap not being tight enough, forgot the code but remember it being very small fuel/ emission leak

https://cimg9.ibsrv.net/gimg/www.fit...9d75f547c2.jpg

I would top up the gas tank, make note of mileage, and do this for a few tankfulls, noting the miles since the last refill, and manually calculate mpg....the mpg gauges can be inaccurate, but if you're getting 200-225 miles on a tank, something has to be wrong, hopefully something minor. Wish I had more to offer. I typically go 320 miles before refueling, can never get more than 9 gallons in at that point, if even...

Friendly reminder, there is a sticky thread for fuel mileage related discussions = https://www.fitfreak.net/forums/3rd-...scussions.html




Back on topic:

I've got more miles than you, and higher mpg's

Could it be something simple?

-low tire pressure?
-dirty filters?
-new commute?
-new bowling ball in the back seat?
-heavier right foot?
-any changes to the car? (new "cold air" intake?)

WOW:

I have 70K miles. I beat the F _ CK out of the car with my foot mostly in the accelerator. Most of the time the car dash color is whichever the poor fuel economy color is? In addition I have 16X7" aftermarket wheels with sticky 205/50R16 tires that don't lend themselves to fuel economy and I still average 37-38 mpg.

If it's still under warranty take it to the dealer.

Stuck brake pad/caliper?
Very mis-aligned wheels?
Your tire pressure gauge is reading wrong so you're way underinflated?

A/C or Defrost left on inadvertently?

Yes start with the basics.

Also note down any check engine lights. When did they come on. How did they get cleared?

How long are your oil change internals?

Even if you are not using top tier gas, added detergent, changed the oil, drove with AC on/off, leaded foot or the tires are under.tire pressure you should be getting better mpg than what is shown. Definitely, something substantial that is causing a meltdown in mpg. First, if you are accurately measuring the mpg manually, you will notice the Honda mpg indicator is generous by 2 to 2.5 mpg on a full tank of gas. That's not the issue here. I suspect there is a gasoline leak somewhere or a crack vacuum hose. Are there a lot of black soot in the tail pipe (running rich mixture of gas/air) or does it look blue (good gas/air mixture).

the switchover to winter blend gas was made a few weeks ago and it really pushes down the mileage.in my Fit

What kind of driving are you doing? Less then 30mpg is obtainable in stop and go traffic. If your driving routes have not changed then your 3mpg drop could be the winter blend.

Fill the tank reset the trip and take it on the highway for a good 30-45 minutes and see what you get.

Thank you for all the suggestions and feedback I did look at fuel related topic and haven't pin point a solution and after 25 page I gave up.

My tires are new I replaced them a month ago and checked that they are all at 32psi. I only use the car to commute to work so I can say 85% of the miles is freeway miles and I do not drive hard. I changed my air filter to the rechargable K&N but not sure that it will affect the gas mileage. I also got brand new brake pads and rotors not too long ago but the bad mileage has been there before the rotors and pads were changed. I live in the bay area and rarely use the AC.

I do have a full system in the car which makes the car heavier and I drive with 2 baby seat all the time since after work I go straight to pick up my kids. One of the seat is 20lb the other is just a booster.
https://www.fitfreak.net/forums/3rd-...m-install.html
https://cimg2.ibsrv.net/gimg/www.fit...05aaac879b.jpg
I do suspect there is a leak somewhere and Im afraid to bring the car to the dealer because currently I dont have the funds if its something major. So Im reaching out to see if there is something I can do or change myself.

Thank you

I dont think its the gas because I see the reading at 30mpg for over a year and half now but for the past 2 months it went down to 27 so thats why im reaching out for some help. These are mostly freeway miles going about 65-70mph.


I'll go fill up now and then manually calculate the gas mileage on the next fill up.

Bump up your tire pressure. 32 PSI is needlessly low.

I run 38 PSI in my car. That'll help a bit on the freeway.

https://cimg8.ibsrv.net/gimg/www.fit...cf69178e10.jpg
I would say your exhaust look normal compared to my exhaust.

If you're in the bay area and routes have lots of hills with stop and go driving you won't get great gas mileage. That's pretty much the worse combo for gas mileage. There's really not much you're going to be able to do absent of moving.

Hey 2Rismo2 I agree with you on this one and if that was the case for me I wouldnt even reach out for help. But I do not drive downtown, I live in the outside of San Francisco the sunset and work in South San Francisco my commute is at 6am never stuck in traffic at that time and only takes 19mins to get to work about 11miles one way. I take the 380 freeway to work then home so mostly its freeway miles. I'll ask my mechanic shop to do a vacuum test and see if they can find a leak.

Are you still on the original fuel injectors? The '15's had a pretty high failure rate. I wonder if this is the first sign of injector troubles to come?

I'd be tempted to pull the spark plugs and see if any of them give signs the car is running rich.

Hi Gafit good point regarding the injectors and honda did replace them the week when the bulletin came out few years ago. And I do recall telling myself when they replaced the injectors my gas mileage gotten worst but at that time I was taking the bus to work before my office moved out of town so I never really thought about it. I do remember my gas mileage gauge was showing 39-42 before the injectors and went down to 35 afterwards. What would my spark plug looks like if its running too rich? I can take one out and take a photo over the weekend.

If running rich, plug will be black and sooty. Can be cleaned off with some carb cleaner..

I'm guessing it's all this...
 

"I did have a few times check engine light turn on and believe it was related to the fuel cap not being tight enough, forgot the code but remember it being very small fuel/ emission leak. "

And unfortunately my further guess is it's NOT as simple as simply the fuel cap not being tight enough.