Question
I planted an Autumnblaze about 3 or 4 years ago.  It was about 12' tall with a 3' caliper. Last year the bark on the west side of the tree was dead, separated from the tree, and breaking off.  The area affected was about 18 inches off the ground to about the 5 foot mark.  At its widest it was nearly half the circumference.  I cut back the dead bark to healthy tissue, saw some callous indicating the problem had been present for a while.  Tiny little bugs were everywhere under the bark near the transition area between dead and healthy bark.  I don't know if they caused or just benefitted from the situation, but killed them with insecticidal soap anyway.  This year the callous is completely surrounding the exposed heartwood, but there are several 1/4 inch wide cracks in the wood.  The tree has added several feet in height, but no significant increase in foliage density.  Am I better off starting over or can this tree be saved?

Answer
No sounds like the tree is recovering nicely. It sounds like a case of sunscald. Young maples are particularly susceptible to sunscald. Sunscald is basically a bark injury and the tree will usually quickly recover. The bark splitting isn't something you can really do anything about after the fact. You can gently cut any loose bark off --this will allow the tree to heal faster.
Sunscald or sunburn occurs in late winter when the sun is bright ?especially if new snow is on the ground. Sunscald usually occurs on the south or southwest side of a tree. Thin bark on the tree is warmed enough to become active. When temperatures fall sharply at night, the inner living bark is killed. Thin-barked trees such as maple are most susceptible, especially when young.

I would watch the area and if you see signs of sawdust or holes in the area I would spray the wound with an Insecticide called Merit or onyx, These will control any borer type insect that might attack the would.  I would also fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. If you apply the fertilizer just before a rain storm you will not need to water. This will increase the growth and the wound area will heal faster.