I think it's say: "I'll come for a limit of time?" but I'm unsure about this
My hunch is "It's about time" or "It's high time".
"ちゃう" is a verb used in casual speech of "しまう" which is often used for unintended actions.
Therefore "来ちゃう" means as same as "来てしまう”.
Hence, I guess it means when you are talking with someone else
"We need to hurry up. The time limit is coming."
or in your head
"I should hurry up. The time limit is coming."
But, for sure I need more context to determine what this sentence wants to say.
Hope it helps.