03 Elantra Tune-up help

On your car, a tune-up consists of replacing the spark plugs. It's also recommended to replace the air filter. But unless your car is misfiring or you've badly neglected your air filter, I wouldn't expect either of these to significantly affect your fuel economy.

I'm no expert on fuels, but if the gasoline was reformulated in your area within the past year, this could be one cause. I am now noticing 10% ethanol stickers on fuel pumps in my area. I don't recall seeing that a year or two ago.

Here's what I'd recommend checking:

-- make sure tires are fully inflated

-- check your tire wear to see if it indicates a need for alignment

-- if your check engine lamp is on, diagnose the trouble codes

-- if automatic, check to make sure your car engages all four gears.

-- if automatic, also check to see if the torque converter clutch (TCC) engages at steady highway speeds on level ground. You may have difficulty doing this. The best advice I can give is to check when you're on a reasonably flat highway with little traffic. Once the torque converter clutch engages, lifting or depressing the accelerator pedal slightly will not make the rpm change. The transmission control module regulates when the TCC engages, so it may take a significant amount of practice to learn how to get it to engage.

I think that's about the limit of what you'll be able to do yourself.

Thanks for the info, it's a manual transmission, so maybe I'll change brands of gas to see if that makes any difference.

It probably won't make any difference, since most gas now has 10% ethanol to replace the MTBE that used to be in it. On the upside, you don't need to buy Drygas anymore to remove water from your fuel system, since the ethanol in the fuel does it for you.