I tried using Ener-G egg replacer for box mix cake as well as scratched recipe ... In both the time my cake crumbled a LOT.. How do I fix it? I followed exact instruction on egg replacer box ... Both the time cake was fluffy, tooth pick came out well dry.. but while eating felt like its little odd.. Box mix felt soggy & scratched one felt dry with crusty top & little powdery .. very odd :( Any suggestions on how to fix this issue..?

AI have never used Ener-G egg replacer (not available where I live) but I remember reading that it was mainly starch. If that is the case it would explain why your cake came out dry/crumbly I think. I prefer to replace eggs with a mixture of ground chia seeds and a few tablespoons of water. By the way, did you realize that you posted this question three separate times?