Bought my '00 Civic DX hatch this past monday and filled up the tank... when i went to fill it back up tonight, i took checked my milage... divided the miles traveled by the gallons put back in... i averaged 26.5

i drove around 245 miles according to my tripometer, and put in 9.324 gallons... averaged 26.3mpgs... i know these cars are supposed to get around 34-38 miles per gallon... just needing advice on what the problem could be... i'm guessing one of two things, just wanting another opinion...

my opinion is... either a sensor somewhere but no cel light on...

or, the car was a thieft recovery and the thief had stole the rims... if they had stole 16" rims and the guy now has 14" rims on it, if the tripometer and odometer had been adjusted for 16" rims could my odometer and tripometer be off and if so, any idea on how much that would make a difference in reality, like how many miles?

 

That all depends on the size of the tires, and the overall diameter of the wheel and tire combined. If the person who changed the rims used the correct tire size (the one that would cause the overall diameter to be the same as before), then the overall diameterwill bethe same (or very close) for both rimsand it won't make a difference.

 

okay, didn't think of it that way... any other problems that would net me approx 8-10 mpg loss?

full tune up in order??? just bought the car... already ordered cai to replace stock airbox.

 

well it's not a bad idea to check the tire size.it will written be on the side of your tires. Your civic needs to have 185/65-14 size tires.

It could be a number of things. Always good and cheapest to start with the basics

 

doing an oil change probably tomorrow... probably plugs too, gotta stop by o'reilly's to see if they have any NGK V-Power plugs in stock...
know of any place that keeps NGK wires in stock? btw... i've always been partial to NGK...

new o2 sensor(s)? is there just one on the DX? or 2?

 

Does your check engine light work? It should light up for a couple of seconds when you turn the key on but don't start the engine. If it never comes on, someone likely disconnected it to hide a problem.

 

According to the 2008 revised mileage estimates, your reported 26.5 miles per gallon is not far off the 27 miles per gallon they report. Since the weather is cooler now,the mileage may also be a little low. If all your miles are city driving, you are even beating the average. If your tires are smaller than the ones that came on the car it will show as increased (inflated) mileage. Tirerack.com shows revolutions per mile of their tires so you maybe able to compare your current tire size to that which came on your car.


http://www.fueleconomy.gov/feg/calcu...1&id=15673

 

Not to mention even with all the info you'd give us, I'd give a 90% fail rating for finding the problem on a forum, rarely do I ever see issues like this resolved from forum advice, the car needs to be in the hands of someone to truly find the problem

 

kk, thanks guys... lol the main reason i bought this one was for the high gas mileage... the problem may have been that i about have to keep the car in 4th on interstate to keep it up to speed... i was just thinking of that...

i did about half and half... city and highway...

and i think i may have a vacuum leak somewhere, can't find it but i can hear that low whistling sound...

and mine is a 5speed, so this is more accurate

http://www.fueleconomy.gov/feg/calcu...1&id=15674 i'm still off from where i should be...

 

Something is wrong with your car. I get over 30MPG with my '00 VP sedan. I also have no problem maintaining any speed limit in the country, even at altitude, and I have a power-sucking auto tranny.

I would definitely give it a full tune-up, and be sure to check the timing. The timing belt may be over-due for a change. Do a compression check in each cylinder first, clean the fuel system, and check for any vacuum leaks.