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Hi, i have a 08 Civic 4dr with 1.8 and AT.
My civic has always drank a lot of gas since i got it like between 10.5 and 11.7L/100 i think its a bit excessive since i don't always stay in city or floor it.
I recently changed the serpentine(was due since cracked), air filter and spark plugs and did the oil change when it was due.
The car currently have 255k kilometers and no light in the dash. Any solution to have better gas mileage? I did like 312Km on 36Liters.
My 03 accord with v6 always floored had like 10L/100 something is probably wrong with this civic and im trying to find what.

Thanks

 
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Can you actively watch the fuel economy? If so, see where it is under certain driving conditions (highway, city, etc)

 
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No i can't my civic is the basic one i don't even have powerlocks. Its kinda the car i had with the less options.

 
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It can be a bunch of things. Start with tire pressure as that'll definitely contribute. How much does the car sit and idle without moving? That'll contribute. Could be that there's a fuel leak somewhere and you're losing it over time. Do you have the AC on much? Other than driver habits, that's about it.

 
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Tire pressure is good. No A/C anyway its getting cold outside lmao. I try to not let the car idle as its waste of fuel. I looked under the car and can't find any leak even on the fuel pump its good too.

 
Rep Power: 125

It's really only three things then. Bad fuel flow (injectors, fuel pump etc, fuel leak, or bad driving habits.

Did you actually check the tire pressures or did you give them a visual check? You won't notice the tires are low visually until they're below like 20psi.

 
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I used a pressure tester. Can it be my cat that could get clogged? Anyway that car starts to have some bad rust at few places i probably should not have bought it when i did in june. Its rotting near the trunk on driver side. I really need to inspect my cars better.

 
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It could be, but usually you would have difficulty starting and it would trigger a check engine light. Wouldn't hurt to get checked, I suppose.

Depending on where you live, it doesn't sound like it'll pass an inspection. Definitely won't with a clogged cat.

 
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No inspection required unless the car isn't plated for more than a year or a cops require it because he see something wrong. Me and a friend looked everywhere under the car and could not find any leak it was dry.

 
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change o2 sensors

 
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-Could have a brake dragging, hurting fuel economy.
-Colder weather hurts fuel economy as well. Not sure how cold you're talking about.
-Short trips where engine barely warms up or highway driving?
-More fuel is added when engine is warming up. Stuck open thermostat and short trips causing poor fuel economy?

 
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Well i bought the car early summer and it was already bad on fuel economy.
I am thinking about brakes dragging how do i check that? I try to push back the pistons?

 
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Look for excessive brake dust on one or more of the wheels. Can also use a temperature gun to see if one of the wheels is hotter

 
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Can also park on level ground, put transmission in neutral, then try to move the car by hand. Should be able to push it without too much effort.

Another option is to lift the front/rear up then try to spin the wheel. Fronts are a little more difficult due to transmission/differential.

 
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I admit my front wheel quickly get dirty tho

 
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Both or just one?

 
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Both

 
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o2 sensors on the way out can also cause the ECU to throw more fuel than needed.
If you don't know if they ever replaced, time to try that

 
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Wouldn't o2 sensor throw a code?

 
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they lose efficiency gradually until eventually it throws a code. Not a sudden death

 
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So it can be near a code but not yet on the code. Which o2 sensor i need to change?

 
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primary

 
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Which one it is upstream or downstream?

 
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Upstream.

 
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Upstream does the measurements, downstream (secondary) checks if the cat is still alive (meow)

 
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So its the one that cost the most if i understand.

 
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Yes but you should actually do testing and figure out what's wrong instead of just blindly replacing parts

 
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Yeah i will check the calipers first then idk what to check.

 
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Well i can confirm that the calipers aren't the problem piston came back easily.

 
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How about the slide pins?