Abstract: A pair of support members and a pair of drilling units are mounted for reciprocal movement along a carriage. The support members secure to latch bolts on an elongated surface to be drilled. The drill units move along the carriage in both an X and Y direction to automatically drill holes in the surface. The drill units are then secured to latch bolts and the carriage with support members advanced on rollers located in the support members. The support members are secured to the next latch bolts and the process continued until holes are drilled throughout the length of the surface to be drilled.

Abstract: An EGR valve control signal developed by the EGR modulator circuit for controlling the EGR valve is combined in a feedback loop with a signal representative of an engine combustion condition, e.g. engine knock to modify ignition timing through advance or retard.