Getting redirected to session_expired using Grinder script on Rails 3 for load testing website- API testing

I recently created an API for a website. Now I was doing load testing using grinder script in which the user logs in, goes to home page and then the blogs page, submits the blog and then the api service is called and it gives a response which is then stored in our DB. It works fine through browser but when the same thing is done through recorded Grinder script I get Filter chain halted as :login_required rendered or redirected in my rails app log. I have tried commenting protect_from_forgery have also given skip_before_filter :verify_authenticity_token in the controller but still for every request made it keeps going to session_expired. Please help.

I am using AJAX for posting blog and getting response from the API. And I cannot remove the login mechanism for testing purpose load testing has to be done with login functionality.