4 yrs shudnt be a problem as far as getting in is concerned but dont expect to crack those i-banks, consults if your work ex isnt relevant unless -
U manage a top 10% rank in your class
OR
Have a fodu profile (preferably with an IIT tag)
This should be a better question to ask - Will I be able to do what I want to do in an IIM with 4 yrs work ex ??
If u cant, to hell with the IIMs, look for other options
If u dont know what u want to do u, write CAT, u wont lose anything