A combustion power framing tool the invention has a nosepiece for driving fasteners, a housing and a combustion chamber that produces primary power held within the housing. A fastener supply, such as a magazine, is attached to the housing to supply the fasteners. The tool has detects a condition and produces a signal based on that condition, then causes the primary power to vary in relation to the signal, returning the primary power to full power following driving of the fastener.