note that this is a 7 year old thread
" It did in fact clean out carbon.", also water sprayed into the intake of a running engine will clean out carbon, like steam cleaning. The question is whether the FJ engine actually ever needs it.
With modern fuels, and the sophistication of modern engine management systems, it is probably unlikely for much carbon to build up enough to matter to the running of an otherwise healthy engine.
As with most products like it, though, using it ought not to hurt.