Hi Gautam,
Is this a synchronous or asynchronous scenario? Do you have any Web Dispatchers anywhere along the message flow (PI/ECC)? These can act as a bottleneck if ICM timeout parameters are not configured similarly on them.
If synchronous check this resource (some steps valid for async also):
PI Troubleshooting Tips: How to Tune PI Synchronous Scenarios
How to Investigate Timeouts In Synchronous XI PI Scenarios
Regards
Mark