Just convert your tab to comma
var path = @"c:\polsamples\POLList_201633.csv";
var lines = File.ReadAllLines(path);
var newLines = lines.Select(l => string.Join(",", l.Split('\t')));
File.WriteAllLines(path, newLines);
Microsoft.Office.Interop.Excel.Application xlApp;
object misValue = System.Reflection.Missing.Value;
xlApp = new Microsoft.Office.Interop.Excel.Application();
xlApp.Workbooks.OpenText(path, Microsoft.Office.Interop.Excel.XlTextParsingType.xlFixedWidth);
xlApp.Visible = true;