Gas mileage has dropped serverly

radeon55 · Jan 23rd, 2007, 11:40 PM

I have a question about the 2000 hyundai accent that i use for work. I have noticed this past month that i have lost over 50 miles to a full tank of gas. I changed the fuel filter, air filter, plugs and wires and did an oil change sunday and still have not noticed any chage except for that before i did all that i was getting 240 miles to a full tank and yesterday when i filled it up i drove 225 miles before i was on empty. I work for pepsi so i drive my car everyday and everywhere for work and it has been getting very expensive this past month i have spent over 100 dollars a week on gas. I also used a fuel injector cleaner on it to. Any suggestions on anything else i could do to get it back to where it was would be great. Thanks Forgot to mention that almost every mile is all highway, not sure if that will help or not just thought i would let you all know. Again thanks

***Jeff*** · Jan 24th, 2007, 10:30 AM

No check engine light on?

I'm not too familiar with Hyundais but does it have a knock sensor? If my knock sensor goes out on my Maxima, I will lose about 50miles/tank.

radeon55 · Jan 31st, 2007, 04:58 PM

Yeah, just haven't had time to get a diagnostics done. Until yesterday, i got suspended from work

It's throwing two codes one for the cat and one for a small leak in a vaccum line. But thanks for the help.

***Jeff*** · Feb 1st, 2007, 08:39 AM

Well the vacuum leak could cause your engine to run 'rich'...thus reducing your mileage.
If I'm not mistaken...so could a bad cat.

radeon55 · Feb 20th, 2007, 01:41 PM

Yeah the bad cat will reduce the mileage. i go on vacation next week so i will have time to fix both and hopefully fix the problem