I've gone through about 8 bags of WGC and it pretty consistantly gives off ammonia smell. I'm pretty sure i let it burn long enough before cooking:
I light the grill, bringing to 375*, wait 45 mins to an hour. Put baked potatos on for an hour, then finish steaks at sear temps (~550*).
I can detect this smell even after burning for 2 hours. I try to load enough lump to get me through all this w/o loading too much.
Never had the happen with the BGE lump coal