About 1 yr ago I remodeled my house and installed about 1800sf of shaw engineered hardwood. I used the glue together floating method. There is one spot in the kitchen that I knew i should have leveled better. I am starting to notice some tongue seperation due to the void under the planks. I am in desperate need of any ideas how to fill the void. I understand the right way to fix this is to pull up the floor relevel and reinstall. The issue is that would be a complete loss of the flooring as it is all glued together and it would cost thousands. I was considering the injection kit and injecting something non adhesive so I don't run into expansion issues. Can anyone think of anything to try here? A complete year out and repurchase would be devastating. Thanks!

Do you have any of the original material left?

If so, you may be able to cut out one board in the affected area, level the hollow spot beneath, and then glue another back into place.
To glue another into place, you will have to glue a ledger all the way around the existing floor for the new board to attach to. Get an epoxy with a mixing tip and apply to the ledger board and slide it underneath the flooring, leaving enough exposed for the replacement board to sit on. Then, after this glue sets, epoxy the replacement board in. You will be unable to use the t&g so you must be certain the area is clean and prepped properly.
This is not a guaranteed fix, but it may be a way out for you.

find a matching or close to matching silicone/caulk..

ledger strip isn;t gong to work..it s a suspended floating floor.

therefore the board must attach to the floor itself to move with it..its possible,

the only issue now is how much is this deviation?

At one time, a board replacement for a laminate floor involved using formica samples that were epoxied under the surrounding floor and had edges extending to the exposed area. The new piece of laminate was then epoxied to these exposed edges. This is what I referred to as using a ledger strip. The difficulty will be to find something that is both thin enough and strong enough to use.

If you have a gap and replace the plank/s you'll most likely still have a gap.

The gap is probably 1/4 inch and is more if a pit than a long steady slope. I have an injector and was thinking if I could inject some material to fill the void I would be in good shape. The issue is most materials that can be injected have some adhesive properties.

Can't use an injection method for floating, that would bond it to the underlayment and it won't be able to expand and contract.

This may sound crazy but I have been experimenting on a test setup with spackling compound. It flows smoothly through a small injector and doesn't really bond to anything once it's in there it seems to just crumble with no adhesive qualities but still provides a basic material to take up space in the void. Am I crazy?

Problem with injecting under wood is the amount of water in it. that can make a worse mess.

Yes that was a concern. Do you think that amount of water evaporating under the floor would cause issues? I assume wood glue has some water content as well but I'm sure not as much because I have seen that injected before.

Can anyone weigh in on if it is a bad idea to inject something without adhesive qualities under engineered hardwood? Would that amount of water evaporating from something such as spackling compound create issues? I am probably only talking one small tube.

I think it would be a problem. It is not going to evaporate but will soak into the underside of the boards.