Fuel Mileage [Archive] - Hyundai Elantra Forum

: Fuel Mileage

05-09-2006, 02:38 PM
I have a 2001 Elantra GT 5 door. The car was getting on average about 28 to 31MPG (according to the computer on the dash) since I bought it with about 40,000 miles on it. I have about 86,000 miles on it now and it averages about 24MPG. I have replaced the spark plug wires with high quality wires and I am running Bosh Platinum 4 spark plugs. It had Bosh Platinum 2's in it when I changed them. It was getting good milage with those. The gas mileage seemed to have slowly lowered over this time frame. The plugs and wires are good and it has a clean new air filter all the time. The dealer says to get a fuel injection cleaning which included the throttle body.

Has anyone had this problem?

Also, I have a Haynes Book for this car and it doesn't explain where the fuel filter is or how to replace it very well. Can anyone tell me where the fuel filter on a 2001 Elantra GT is located and is it strainght foward to replace? Is there a fuel press. valve to deal with before replacing the fuel filter?


05-09-2006, 02:43 PM
Fuel filter is in the tank. You need to remove the seat and you'll find an access panel. Make sure you're almost on empty when tackle this job.

05-09-2006, 02:55 PM
you dont need it to be almost empty to change it. theres going to be fuel in the bucket either way

dont trust your gas mileage to a computer. fill up the tank, reset odometer, drive, fill up, divide miles/gallons you put in. this is 100% accurate

the other thing im hoping will help me soon is to get the IM cleaned out inside of it. when i pulled it last weekand pulled the TB, there was so much built up gunk inside it was crazy. im hoping when i get the ported manifold and its cleaned out (or ill clean it if it isnt) it will help a bit.

i was reading the other day that "ever since cars started coming fuel injected people have had issues with the TB sticking or something similar. when cars were carbuerated and the fuel went thru the IM it acts like a cleaner"

05-09-2006, 04:17 PM
get the pcv seperator and it will help with the gunk, when i took off my intake manifold i really didnt have that much crap and i have 95k miles on mine

05-09-2006, 04:49 PM
My mileage is pretty random but it has everything to do with my driving habits. That's a pretty big decrease. Your O2 sensor might be causing the problem.

Also, have you changed tires recently? When I switched my car from 195/60/15 (that were actually smaller in radius) to 185/65/15 my gas mileage appeared to have gone down. But the car's spedometer was off about 5% on 195/60 but right on at 185/65 and when I accounted for that 5%, gas mileage was the same.

05-10-2006, 04:34 PM
smaller tires will do that. what happens is when youre actually doing say 70mph, your speedo is going to read 75mph which will be using more fuel.