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Hi guys.

I have pretty bad gas mileage on my 2003 accord. I can't say exactly when it started but if I had to say, it's been noticeably bad for about 2 years now.

I get about 250 miles per tank of gas. With a 17.1Gallon tank, that's about 14.6 miles per gallon. Even driving mostly city miles, that's really poor.

I changed the MAP sensor hoping for a cheap fix but still the same. I had the Cat changed to fix a 420 code about 2 months ago, and no change.

Filters are clean. My next step was to change the spark plugs. I haven't changed them since owning the car, so I figured it's a good idea.

But any suggestions would be greatly appreciated.


Thanks.
 

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How many miles on your car ? V6 or I4 engine ? Do you do a lot of city driving (LA or NYC type) ? What kind of mileage do you get if on a uncrowded interstate going 65 mph on a tank of gas ? You can check fuelly.com to look @ what others are getting for the same type of driving. Plugs get changed every 105K, but Honda's are so good about being able to meter the combustion process you probably wouldn't see a big jump in mpg. First put in a can of BG44 in the gas tank, it will clean up the fuel system.
 

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How many miles on your car ? Do you do a lot of city driving (LA or NYC type) ? What kind of mileage do you get if on a uncrowded interstate going 65 mph on a tank of gas ?
151,000 miles. I live in Queens NYC. I do almost nothing but city driving. In the summers I'll go to Virginia Beach or Upstate NY. I get slightly better gas mileage, but still underwhelming, I would say 18MPG. My wife has a civic and even in the city she gets 330+ miles on a tank

That's not how you calculate MPG
Ok fine you can enlighten me on how to calculate mpg. Regardless of how you calculate it. I am sure I am not getting good gas mileage.

However, I would think that dividing the miles driven by the amount of gallons used is not too far off:

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(MPG)
Fill Up and Record
  1. Fill up your gas tank all the way.
  2. If your car has a trip odometer, reset it, or record the master odometer mileage.
  3. Drive your car as you normally would, and let your gas tank deplete to at least a half of a tank of gas.
  4. Get to the gas station and fill your tank again.
  5. Record the amount of gas it took to refill the tank.
  6. Record the elapsed trip miles or new odometer mileage.
If there is some complex algorithm that you are aware of and wish to share, please do so. I am more than willing to to listen.
 

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Ok fine you can enlighten me on how to calculate mpg. Regardless of how you calculate it. I am sure I am not getting good gas mileage.
You can't be sure of anything unless you correctly calculate MPG.

However, I would think that dividing the miles driven by the amount of gallons used is not too far off:
Yes, the correct way of calculating MPG is to divide number of miles driven by amount of fuel used. But that's not what you did per

I get about 250 miles per tank of gas. With a 17.1Gallon tank, that's about 14.6 miles per gallon.
because you didn't use every last drop of fuel in the tank, did you?
 

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@ fill up reset your trip odo. Then you divide gallons you put in @ next fill up by the trip odo. BG44 in gas tank to clean fuel system, if missed in my edited post may help some, but as others have stated here that live in NYC, they get 14-15 mpg with a 4 cyl. accord. The civic has a smaller engine.
 

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You can't be sure of anything unless you correctly calculate MPG.


Yes, the correct way of calculating MPG is to divide number of miles driven by amount of fuel used. But that's not what you did per



because you didn't use every last drop of fuel in the tank, did you?
I suppose using the gas meter's account of how many gallons I've put in would yield a more accurate calculation; however, I am virtually on the Empty line when I fill up the tank. So I doubt the 10 miles or so I would get out of the last 1/2 or 1/4 gallon in the tank is going to change the mpg to any significant amount. Unless the tanks volume has changed significantly for some reason or the reading on the dash is incorrect as to how close I am to being empty, there should not be a significant difference in using the tank's capacity. Anecdotally, I certainly seem to be paying for a near full tank of gas.

Let's say I have 1/2 gallon left when I fill up, so that would mean 250/16.6 = 15 MPG which is still poor (using the capacity of the tank minus the 1/2 gallon). Were not talking a difference of 2 or 3 mpg that may seem reasonable but I would say more around 10 mpg.

I do reset the A and B temporary odometers to records the mileage.

However, next time I will record how many gallons I put in and reset the odometer to record the mileage to see if that yields any notable difference.
 

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When my gauge hits empty, I still have about 3 gals. left. I have read that Honda does this so you won't run out of fuel.
 

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A failing O2 sensor can ruin a new cat, is the engine using oil ?
 

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If nothing else was done but replace the Catalytic converter , then whatever killed the first one will take this one out as well. Low fuel Efficiency in an car can be a lot of things.

1. Fuel (winter blends are different)
2. Replacing the spark plugs will help a bit.
3. Tire inflation, set it correctly
4. Make sure no brakes are dragging.
5. Wheel alignment
6. Oil viscosity should be 5w20
7. Check timing
8. Clean fuel injectors
9. Driving habits
10. Transmission issues.
11. Exhaust system in good shape.

I doubt in NYC traffic you will get above 20, it was rated new at 21 city, 31 hwy. I suspect the best you will probably ever get is 17 or 18 and that is if you drive very carefully.

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ziptie princess
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i have a 2.4/5mt and averaged like 15mpg over my last tank (no, i don't remember the numbers, i just remember laughing because it was especially bad)

these are garbage in the city tbh
 

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i have a 2.4/5mt and averaged like 15mpg over my last tank (no, i don't remember the numbers, i just remember laughing because it was especially bad)

these are garbage in the city tbh
I get 15-18 mpgs on my Subaru with e85 map lol. Which I might put up for sale soon sadly. I kinda like the quiet ride more and more now.

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yeah I'd just like to chime in, something is definitely not right, or your MPG was not calculated correctly.

I had a 06 LX that I had for almost 7 years. I almost always got close to 30 mpg combined every tank. If not, at least 27 or so plus.... the lowest ever was a close to 100% city/local tank in a cold asf winter... where I used a whole lot of A/C. I got about 19-20 I can't remember the exact number, but it was around there, definitely the lowest ever for me.

Even my more recent LX-SE (that I got for commuter) was getting 23-25 mpg, which was lower than I expected and one reason I got rid of it not too long after. I was expecting about 30 mpg, but that didn't happen. Oh well.

IMO, like others have suggested, either 1) something is terribly wrong, 2) MPG is not calculated correctly 3) NYC truly has crappy traffic, which I believe is the case based on my limited experience (but during pandemic?), at least you should be getting decent mpg these days.
 

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yeah I'd just like to chime in, something is definitely not right, or your MPG was not calculated correctly.

I had a 06 LX that I had for almost 7 years. I almost always got close to 30 mpg combined every tank. If not, at least 27 or so plus....
^Agreed.
My '06 coupe does pretty much those exact same MPG numbers.
And winter fuel(in my region, NE) lowers my MPG by at least 2.5 MPG in both of my Accords..
Another reason to hate winter..lol..
 

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ziptie princess
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I get 15-18 mpgs on my Subaru with e85 map lol. Which I might put up for sale soon sadly. I kinda like the quiet ride more and more now.

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bad tune or baby turbo?

my 450whp escort used to average 28 city/hwy (highest was 33) and that was with a stock ecu and 9:1 afr at full boost lmao
 
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