Fastener-driving tool with one or more combustion chambers and an exhaust gas recirculation system

A method of operating a fastener-driving tool including a housing, a combustion chamber in the housing, a cylinder in the housing, an air chamber, a piston chamber in the cylinder, a piston in the piston chamber and movable relative to the cylinder from a pre-firing position to a firing position and back to the pre-firing position, and a driver blade attached to the piston, said method comprising:

• communicating a first portion of exhaust gases from the combustion chamber to atmosphere via an exhaust conduit;
• communicating a second portion of the exhaust gases out of the combustion chamber and then back to the combustion chamber;
• and
• communicating a third portion of exhaust gases from the piston chamber to the combustion chamber through use of an exhaust gas recirculation system comprising an exhaust gas recirculation conduit connecting the piston chamber and the combustion chamber and a plurality of outlets,
• wherein the exhaust gas recirculation system is configured to promote the flow of exhaust gases and is capable of being in fluid communication with the air chamber, the atmosphere, the cylinder, and the piston chamber via the plurality of outlets.