Auto-generating SCHEMA.INI

Power Pivot (and Tabular) uses the Access Connectivity Engine (ACE) provider to import from text files. This provider was originally designed for Microsoft Access databases and it's limited to import files no larger than 2 GB (or 4 GB with the Office cumulative update from April 2012) as explained here. The Power Pivot Table Import Wizard allows you to import from delimited files and only a subset of delimiters are available for you to choose from.