2017 hatchback sport was getting decent milleage now its not

[deathjam4]

So my honda civic 2017 hatchback sport has been getting some preaty crudy mileage lately.
I went from getting an average of 7-8 L per 100 km to 10L per 100 km. I have not changed anything I drive in economy mode, purchase gas at the same gas station and always the same type of fuel. I find the higher the fuel type such as 91 octane does not make a difference in fuel consumption it just gives the car a little more kick when you put your foot down, so i just opted to 87 octane and have been driving with that type of gas for over 5 months now.
A few things i have noticed is for some reason even during the hot hot of summer my car will turn on when cold in a high idle as if it was the middle of winter and yet its so hot out side you can cook an egg on the side walk. My car in the morning almost always smells like its also throwing more gas into the engine then is really necessary as i can always smell a heavy concentration of gas around the car but not see any leaks and only smell it at the tail pipe. If this was a VW i could find the issue fast but this is a honda and i am not up to wasting 100$ at the dealer for them to tell me nothing is wrong.

I know this is a big post but I bought this car to save money but in reality its costing me just as much as my high end audi in fuel and I am worried.

**oh and my girl friend keeps reporting to me saying the car likes to surge forward on her with out even touching the gas as if it was still peddle feedback. Had this issue the first month i bought it but atributed it to the shity floor mats i bought. I now have good husky matts in there and have not had that issue in a while.**

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[BogdanM]

You didn’t mention the current mileage or the driving habbits or where it’s being driven (in town mostly or open road). That’s because you f it’s being driven mostly in town, 10 liters per 100 km isn’t that bad. Depends also on the average speed.
For example, mine (EU hatch) has an average of 5.7 l/100 km over it’s entire history, ~7500 km on it so far. Average speed over the entire history is ~47 km/h, 70% of the km done outside city or in rural areas.
Also, very important how much of the time it’s on boost. More boost, more gasoline, that can increase your fuel consumption. You said that your gf drives the car also, take a look on how she accelerates, mine seems to have a hard time being progressive with the throttle. Heavier foot on throttle, higher boost, higher gasoline consumption.
The fast idle at cold start is normal and has no connection with the outside temp. My previous car, also a Japonese one would start at 1600 rpm when hot outside and around 2000-2200 when very cold (below -10 centigrade).
The smell of gasoline at startup is also normal, all cars run richer immediately after a cold start. The smell should disappear after 10-15 seconds though.

 

[racer]

Since I don't do metric for mileage (but thanks to google, my 40mpg average = 5.8l/100km), is the mileage you are getting within expected norms or is it just lower than what you had been experiencing? How long is "lately".. you mention running 87 octane for the past 5 months, but your car is older than 5 months.. what where you using before? Any changes in driving style (or drivers)?

Can't explain away the fuel smell.. that's a bit concerting in a newer car.

Engine warm up normal. The car still wants to operate at about 180-200 degrees, whether its cold or warm outside

 

[Shankmeyster]

Economy mode also doesn't do jack except make you push the pedal harder to get the same amount of power. Turn it off and never use it again. Most people who have tried it have reported no difference in mileage and the reduced power and AC output do not make up for this IMO.

 

[deathjam4]

ok sorry for the long reply fanexpo was this week

Ok so i have 12000 km on my car bought it in feb 2018. The first month i bought the car i was putting 91 octane in it and mileage was roughly 7.8km per 100km this was with a heavy foot on the gas as it was a new car and i was excited. During 2 week periods i would stick to one gas station and the same octane i tested one week of heavy foot one week with driving like a grandma mileage is almost all in town driving most common speed is around 62. I did this with all the octanes of gas so 89 octane and 87 octane. the only difference i seen was a slight difference in power (aka lower octane lower power) mileage only change by .1 per type of fuel so i have stuck with 87 since then and was averaging roughly 8L per 100km. I will often drive like a grandma or at least gently and have been doing so of late to try and bring the gas consumption down.

I get up to a max of 100km/hr on a small high way on my way to work every day consistent speed is 90km/hr and consisted of half my drive and i still get bad gas mileage. This issue is only getting worse and has me worryed i might have a lemon. point in *first week i bought the car had to take it back and have an entire strut replaced due to it not working at all.*

**on a side note i recently removed the bumper to install a new horn and had to disconnect the pipe that comes down from the air box to the inter cooler that runs past the horn. I had a really loud wheezing sound since the first month i bought the car from that corner after removing the pipe cleaning the rubber and properly retighting the bolts no more wheezing and noticed a pickup in power from the car. **

 

[Shankmeyster]

Sounds like you had one of the untightened intercooler pipes from the factory. Several people were reporting this problem early on. Did you check both sides?

 

[colllinwillliams]

I get 29 MPG in sport mode on 93 octane racing it all over

 

[Shankmeyster]

Usually seeing 34 mpg average back and forth to work. If I go long range on the freeway I'll see 40+. Never use ECO either.

 

[10thDave]

So my honda civic 2017 hatchback sport has been getting some preaty crudy mileage lately.
I went from getting an average of 7-8 L per 100 km to 10L per 100 km. I have not changed anything I drive in economy mode, purchase gas at the same gas station and always the same type of fuel. I find the higher the fuel type such as 91 octane does not make a difference in fuel consumption it just gives the car a little more kick when you put your foot down, so i just opted to 87 octane and have been driving with that type of gas for over 5 months now.
A few things i have noticed is for some reason even during the hot hot of summer my car will turn on when cold in a high idle as if it was the middle of winter and yet its so hot out side you can cook an egg on the side walk. My car in the morning almost always smells like its also throwing more gas into the engine then is really necessary as i can always smell a heavy concentration of gas around the car but not see any leaks and only smell it at the tail pipe. If this was a VW i could find the issue fast but this is a honda and i am not up to wasting 100$ at the dealer for them to tell me nothing is wrong.

I know this is a big post but I bought this car to save money but in reality its costing me just as much as my high end audi in fuel and I am worried.

**oh and my girl friend keeps reporting to me saying the car likes to surge forward on her with out even touching the gas as if it was still peddle feedback. Had this issue the first month i bought it but atributed it to the shity floor mats i bought. I now have good husky matts in there and have not had that issue in a while.**

Another person from Toronto. Awesome!

But man, right inside the fuel door it says to use premium/unleaded gasoline. WHY are you using 87!? The car is designed for fuel that burns at a higher temperature, don't be one of those people who use 87 and then wonder why 3-4 years down the line why there engine is all messed up (and yes, it happens).

Not saying you will do any noticeable damage but go back to 91 for a bit and I can almost bet you you'll go back to the normal mileage.

Personally, I get 6.8L/100km to 7.6L/100km as an average. Have 23,000km on my car now.

 

[Shankmeyster]

It says recommended, not required. You can use whatever octane you want, you just won't see full power from it. I wouldn't recommend using low octane in hot climates on turbo motors though as that just invites more knock.

 

[deathjam4]

Ill keep that in mind. I have only been using the 87 octane cause its cheaper for one and I get the same mileage regardless I might bump it up to 89 octane tho Been driving audis for over 14 years and i am sick of high octane requared cars lol at 90$ a tank you don't miss an audi hehe. I was thinking I would run a little seafoam threw the car tho figure the low octane gas might be making more then just a few deposits my tail pipe is soot city can't keep the chrome clean for more then 1 trip before it gets stained again.

And nope did not think to remove or tighten the other side tho i guess i should have. Only removed and cleaned the other side cause it was in the way of the bolt holding that scooter horn on but it did reduce the whistling sound by 60 maybe 70 % which is good.

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