Just read a book implying they hit the mid pacific, circa 1000ad....makes me think..
If the Polynesians had introduced chickens-why not taro? Why not sugarcane? Why not bananas? Why not pigs? These are all very useful things to have, but they don't seem to have been in the Americas during the Columbian contact.
For polynesian contact look at what animals survived on Easter Island which is the closest polynesians to South America, No pigs and no chickens.
The polynesian name for sweet potatoes is very similar to its names along the south american coast.
I would be surprised if there was no contact, there is just no way to find out how much. And yes I would surely like to be able to go back and find out.