InfoPath Dev

I have developed a Quiz application in Infopath.  It submits the user information and their answers to a Sharepoint list.  Then kicks a workflow off for grading the quiz.  The problem I am facing is the quiz needs to have a time limit.  The way I want it to work is:

1. The user enter their name.
2. They now click "Start Test".
3. Answer questions and then click "Submit for grading" at the end of the test.  If they do not finish before the time limit, I would like to display a Message Box telling them the time limit has expired and submiting the answers to the questions they were able to finish.

I have searched and have seemed to hit a brick wall.

Any help will be appreciated.

Maybe when they click Start Test, set the value of a hidden field to substring-after(now(),"T").  Do the same in another field for when they click Submit for Grading.  Then, compare the two?

That would work but, it would allow the user to complete the test and then disguard the whole test.
I need it to submit either by the button or when the timer reaches it's limit, and grade the answered questions and any unanswered are just wrong.

Thanks for the reply.

Don't think you can do something that dynamic without building it in Visual Studio with code

You can add a timer to the taskpane and submit from there. A small amount of code is required. We could write it for you if you want to open a Support Incident. Cheers!

I'm assuming you are not using browser based forms.

Can you post your quiz app PLEASE???  I am trying to find a way to create quizzes in SharePoint 2010.