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Horrible Gas Mileage in 2001 3.0l V6 Accord

I never noticed how bad the gas mileage was in my accord until my gas gauge stopped working last month. I’ve been using 15mpg as a baseline for when to put more gas in the car, and have run out several times. Turns out i get more around 9-11mpg



My question is, what should i change/look at to help my MPG. The car has literally never seen the inside of a mechanics shop. Beside engine oil changes, its had no work done on it. It has 90k miles and seems to run great.



The thing is, i’ve been saving up for a new car and dont want to spend too much on this thing. Im about 2 years away from buying a very nice car w/ cash, so i just need to make this thing last and only do repairs on it that would actually save me money (in gas cost from driving around 7k miles a year). I remember getting over 20mpg when this thing was new… so theres obviously some mechanical problem here. I dont accelerate/stop quickly so i dont think my driving is the problem

Change the spark plugs and air filter, and transmission fluid.

Beside engine oil changes, its had no work done on it.

There is nothing more expensive than skimping on standard maintenance.

Get out the owner’s manual and get it all up to date. Likely in addition to hellokit’s list you may need a new fuel filter transmission filter brake fluid etc.

If it runs good and you get no check engine light, I’d look for a gas leak. Open the hood and see if you smell gas, if not, the leak could be at the tank itself. Since the gas gauge isn’t working, I’d be looking at the tank or a fuel line from it.

Any Check Engine Light on? If the fuel mileage is really that bad then the CEL should be illuminated and the car should not “seem to run great”, according to your post.

Why buy a very nice new car. You state this one has never seen the inside of a shop so why invest in a new car and treat it in the same manner?
Just buy an old beater, flog it into the pavement, and then buy another beater. It’s far more cost effective.

“The car has literally never seen the inside of a mechanics shop. Beside engine oil changes, its had no work done on it. It has 90k miles and seems to run great.”

Yes, it seems to run “great”.

Since an engine’s power output and its fuel economy decline gradually, you have been lulled into a false sense of security and do not realize just how much the engine’s performance has been degraded over the years. In fact, if not for the recent discovery of the very poor gas mileage, you would probably have continued to drive the car in this non-maintained manner until it finally stopped running, simply because the negative changes take place gradually.

As was said, you need to open the glove compartment, take out the Owner’s Manual, and see what maintenance is called for at 90k. This will essentially be the replacement of all fluids, all filters, and the spark plugs. Just doing what is called for should restore most of the car’s original fuel economy.

Incidentally, checking your gas mileage frequently is a very easy basic bit of diagnostic testing that you can do with a calculator. Even though I maintain my car meticulously, I still check the gas mileage right after most fill-ups. If I was to see a sudden drop in my regular gas mileage, that would be an early clue that something was amiss with the engine. You can do this too, and it will save you lots of money in the long run with this car and with all of your future cars.

As to what you have been doing by “cheaping out” with maintenance, take my word for it–
You can’t afford to save that much money.

So I know everyone was shocked at my poor treatment of my Accord, but I did Change the Spark Plugs, Air Filter, and Tranny Fluid. After only one tank it seems that im getting a few more MPG, but not many (maybe 13). I really dont think my driving is the problem (even my mother thinks im a slow driver), so im curious about what the next step i should take here is.

The car does run better after this recent work, and the check engine light is not on.

Thanks

When the fuel mileage drops off, the first two things to have checked are a thermostat that’s stuck partially/fully open, or a defective engine coolant temp sensor for the computer.

Tester

Is there a way to self check the ECU for error codes on this car like i can on my z32 300zx? Or do i need to take it into a shop for diagnostics. I can put in a new thermostat just incase.

Most people get in the high 20s mpg with their Accords. Something must be very wrong with yours, if your fuel usage figures are correct. 90,000 miles doesn’t put a car into “junker status”. Neglect can.
If you know a good mechanic, who can find where all the gasoline is going, you’ll actually be money ahead on vehicle maintenance costs by fixing it.