I have a 2004 diesel KIA sedona that is hard to start. It cranks really slowly. I thought it was the battery, so I had it replaced and it is still doing it. Any ideas?
When a car is cranking badly, there are a couple things to check out. You've done the first: the battery. Beyond that, there are two things you should also check.
First would be the leads to the battery. Are they corroded at all? If so, you should try cleaning them off. Use a stiff wire brush to scrape off the larger particles and then scrub well with baking soda dissolved in water.
If your car still refuses to crank at full speed, you're probably looking at a starter motor replacement.