I WAS GETTING ABOUT 480 MILES PER FULL TANK UNTILL FEW WEEKS AGO. NOW ALL OF THE SUDDEN IT IS ABOUT 17-18 MILES PER GALLON! NO “CHECK ENGINE” LIGHT, JUST GOT OIL CHANGE DONE, AIR FILTER CHANGED.TIRE IS INFLATED TO WHAT IT SHOULD BE…WHAT HAPPEND? WHAT ELSE CAN I CHECK? ODOMETER IS LITTLE OVER 50,000 - HAVE NOT HAD ANY PROBLEM TILL NOW. ANY IDEAS? AIR CONDITION USE IS NOT SIGNIFICANTLY CHANGED.
Why is it that you have always estimated fuel economy by miles per tank but now report miles per gallon? I’m not being picky, your answer might give us a valuable clue.
The only thing I can see that happened is your CAP LOCK key got stuck and you changed from a very inaccurate method of measuring mileage to a more accurate method.
There’s no need to shout!
That’s pretty bad mileage for an Accord, but you didn’t tell us much about the car. 4-cylinder or V6? Automatic transmission or manual?
Do you drive in the city, on the highway, or a combination? More information please, but without the noise.
Because when I used a half tank of gas in one day I start paying attention - that is why. Combination of city and freeway, I was able to drive around 450 or so miles until now - that is about 25 MPG. So dropping from that to 17 MPG is quite steep.
I didn’t realize the accord had such a huge gas tank!!! Anyway, have you been driving with the AC on? Or driving at highway speeds (65 or more) with the windows open?
Did you notice if the check engine light is on, or blinks a little extra-long when you start the car?
Maybe you just made a math error for this tank? There are a bunch of things it could be.
A lot of things can cause a temporary drop in mileage, you may have overlooked something or it may make itself apparent shortly. Two common causes for this are an O2 sensor about to go or a transmission about to go.
Also, sounds like your near the point of needing a tune-up. The platinum plugs in your car last a long longer than the old copper plus plugs from years ago, but they still don’t last forever. I think most makers claim 100K for a set of plugs, but my experience shows a significant performance drop begins about 55K to 65K, and I like to change out plugs every 60K.
Plus, ignition wires may be done for. I’d try a tune-up, including air filter, plugs, PCV valve, check and or replace the ignition wires, and any other recommended services from the owner’s manual. I’m not sure, but I also think some of the Honda engine models still need periodic valve lash adjustments. My experience there is check and adjust every 30K at most.
Your method of using the fuel guage as a barometer of mileage is beyond inaccurate. A fuel guage is NOT linear.
You need to fillup to pump shut off without top off, reset your trip odometer, drive a nearly a full tank and fill up again to pump shut off without top off. Divide your miles traveled by gallons just filled up to get a real #. This needs to be repeated over a few fillups to get a good idea. Compare this to the 2008 epa #'s on fueleconony.gov and see where your car falls.
Oh yeah, i forgot about those valves. Good reply