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Fuel Issue Civic SI

5047 Views 12 Replies 9 Participants Last post by  dennywestcoast123
Hi everyone!

A year ago I purchased my Honda Civic SI 2015, all this time I've been experiencing a bad fuel consumption.

I'm only getting between 400km (248 miles) to 440km (273 miles) per full tank (50 liters) that means 8,5 km per liter.

I changed the sparks plugs because I thought that was the problem but it didn't change anything.

Also when the engine is running but I'm stopped in a red light or just parked with the engine running it use so much fuel because I can see the the fuel indicator goes down quickly.

If you know what is happening with my car please let me know

thank you guys in advance!
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I'd probably start with the basics, whats the Mileage of your Si?
Do you have a lead foot? Either bad driving habits or running too rich.
My first actions would be to run a OBD2 scan & not from a cheap one. Your can can still have codes & not turn on a Check Engine Light.
Unplug the battery terminals to let the computer reset, in the mean time I'd remove the MAF sensor off the intake box & use some spray cleaner from your local auto parts store to verify it's clean. Then let it sit & dry for 20 mins, reinstall.
Again this would be my first approach personally.
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Is that highway or stop and go city driving?
Hey! Thank you for responding.
Actually my driving isn’t too bad in the dashboard it says that I’m getting 7.5/100 kms and then when I press too much the gas that indicator goes up to 8.5 or 9.0 sometimes but most of the times I have on 7.5 or 7.7/100 kms.
Hey man thank you for responding.

This is probably half and half but mostly highway.
Do you refuel whenever the light comes up? Cause when the light comes up the reserve gas can still drive for another 80-100km until it actually runs out of gas. Unless you actually fill up 50L of gas at the station. Cause that never happened to me when I put in gas, when lights on it usually only take about 40-43L of gas to fill.
when was the filters changed? both the engine air filter and the cabin air filter? oil change and filter? what's the air pressure in your tires. if you are all city, you wont' get good mileage. what kind of tires are on the car? as before, there are many variables that attribute to each individual person's mileage.
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Hey! Thank you for responding.
Actually my driving isn’t too bad in the dashboard it says that I’m getting 7.5/100 kms and then when I press too much the gas that indicator goes up to 8.5 or 9.0 sometimes but most of the times I have on 7.5 or 7.7/100 kms.
I'm getting a similar average consumption. In my SI 2012 (coupe) i'm getting an average consumption of 9,2/100 mixed driving (city and highway), that is 10,86 km/ltr.

In driving only on a Highway I´m getting 7,7/100 = that is 12,98 km/ltr. at cruising speed of 120 km/hr.

I Think is very good for a car with a 2,4 ltrs engine and 202 hp motor car using daily
You bought it used, so the previous owner may have done engine modifications, tuning, exhaust......
Best to get back to Honda programming. Check if the Cat-Converter was removed from the exhaust.
Great first trouble shooting suggestions
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You bought it used, so the previous owner may have done engine modifications, tuning, exhaust......
Best to get back to Honda programming. Check if the Cat-Converter was removed from the exhaust.
Most likely if he had his cat removed you would most definitely hear it & without a Tuner an active Engine light would be on. It's less doubtful someone would run a for example Honda-Data & not remove it from the car before it's traded in or repo'd.
Hey! Thank you for responding.
Actually my driving isn’t too bad in the dashboard it says that I’m getting 7.5/100 kms and then when I press too much the gas that indicator goes up to 8.5 or 9.0 sometimes but most of the times I have on 7.5 or 7.7/100 kms.
The problem for you is that you find that there is little average consumption?? for a CIVIC SI, 2.4 liter engine?

The SI here in Chile gives 7,7/100 km in higway and 9/100 km in city(as an average). I don't know what difference you will have there or what average consumption expects there in the USA / Canada, but should not vary, it is the same car, same engine

I personally use 97 octane gasoline
Hey there I get around 400km per tank on my 2015 honda civic si thats all city driving. I thought I was getting poor fuel milage too until I read theses post. Its just a pig on gas in the city.
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