my coca cola cake is the one that always falls why?!
Is the center set? If not, make sure the pan is not a cheap one, because those do not cook evenly. Try leaving the cake in for a minute longer, or thickening the recipe with something like flour, sugar, etc. or any dry ingredient.
Considering your recipe is not at fault, these tips should help.
Do NOT open the door at all once you start baking it. NO PEEKING. Pretend it's a souffle if you have to because it works in a similar matter just not as dramatic.
Do NOT overbeat eggs. It will cause your cake not to rise or rise and fall in the center. Good luck!