Abstract: An in-head compressed air start-up system for an internal combustion engine comprises an absolute angular position detector for the crankshaft outputting an electrical signal indicative of the angular position, a computer for storing a table of the firing order of the cylinders and the angular position of the crankshaft at which each piston reaches a desired angular position relative to top dead center (TDC), wherein the computer means compares the signal indicative of angular position of the crankshaft to the firing order table and generates a plurality of signals sequentially open and close solenoid valves to cause rotation of the crankshaft.