Circuit/System Description

The fuel injectors are mounted in the cylinder head beneath the intake ports and spray fuel directly into the combustion chamber. Direct injection requires high fuel pressure due to the fuel injector's location in the combustion chamber. High pressure fuel is regulated by the fuel rail pressure (FRP) regulator, which is a part of the high pressure fuel pump. The engine control module (ECM) monitors the actual fuel rail fuel pressure via the FRP sensor and commands the FRP regulator duty cycle in order to maintain the desired fuel rail pressure. If a fuel injector delivers more fuel than is needed misfire counts will accumulate on that cylinder, and the ECM will not be able to maintain the desired fuel rail pressure, indicating a stuck open or leaking fuel injector.