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I have a 2003 a Kia Sedona turbo diesel 2.9L, with intercooler.

I am getting 5 km per liter of diesel consumed. I also have to do oil change and ATF replacement. I got the car 3 weeks ago.

What are the possible remedies to improve fuel consumption? Other Sedona owners are getting 8 to 10 km/L on city and 12km/L on highway?

Will oil and ATF change improve mileage? Old oil is likely black and old ATF is smelly and like diesel?

How about fuel filter, injector cleaner, and whatever may be suggested?

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How is your exhaust pipe? Is it black and sooty? Can you smell fuel? Is there any color to the exhaust smoke? – Zaid Apr 15 '14 at 14:00

First thing I'd check is to see if there are any leaks in the intake tract. Make sure all of your cold pipes (pressure side between turbo and intake manifold, going through the intercooler) are in place and not leaking, especially at the joints.

The turbo may be at fault as well. If it has failed, this could be causing a loss of power and excess use of fuel. If you have a boost gauge, you can see that a lack of boost is being built under engine stress. You might also hear what would be considered "more than normal" (or none at all) turbo whine.

If your injectors are dumping too much fuel (stuck open or not closing all the way), you'll obviously be getting poor fuel economy.

Change the oil and ATF, but neither of these should have any real impact as you are suggesting, though bad oil or lack of oil can cause premature turbo bearing failure.

While not any news to you, I'd suspect you should be getting somewhere around 40-42 miles per gallon, where right now it appears you are getting around 11-12 MPG. That is SUCKY!

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