2009 Polaris Sportsman 850 XP EFI EPS Service Manual, Page 54Get this manual
ELECTRONIC FUEL INJECTION ELECTRONIC CONTROL UNIT (ECU)
Operation Overview
The ECU is the brain or central processing computer of the entire EFI fuelignition management systemDuring operation, sensors continuously gather data which is relayed through the wiring harness to input circuits within the ECUSignals to the ECU include: ignition (onoff), crankshaft position and speed (RPM), throttle position, engine coolant temperature, intake air temperature, intake manifold air pressure and battery voltageThe ECU compares the input signals to the programmed maps in its memory and determines the appropriate fuel and spark requirements for the immediate operating conditionsThe ECU then sends output signals to set the injector duration and ignition timingTo prevent engine over-speed and possible failure, an RPMlimiting feature is programmed into the ECUIf the maximum RPM limit (8000) is exceeded, the ECU suppresses the injection signals, cutting off the fuel flowThis process repeats it self in rapid succession, limiting operation to the preset maximum