Abstract: A fuel delivery system for a vehicle having an engine configured to selectively operate between a port fuel injection (PFI) mode, a gasoline direct injection (GDI) mode, and a port and direct fuel injection (PDI) mode. The fuel delivery system includes a PFI system including plurality of PFI injectors configured to supply fuel to the engine during the PFI mode, and a GDI system including a plurality of GDI injectors configured to supply fuel to the engine during the GDI mode. A fuel system monitor is configured to monitor the fuel delivery system when operating in the PFI mode, and attribute any fuel delivery system malfunctions occurring during the PFI mode to the PFI system alone, and monitor the fuel delivery system when operating in the GDI mode, and attribute any fuel delivery system malfunctions occurring during the GDI mode to the GDI system alone.

Abstract: A fuel delivery system for a vehicle having an engine configured to selectively operate between a port fuel injection (PFI) mode, a gasoline direct injection (GDI) mode, and a port and direct fuel injection (PDI) mode. The fuel delivery system includes a PFI system including plurality of PFI injectors configured to supply fuel to the engine during the PFI mode, and a GDI system including a plurality of GDI injectors configured to supply fuel to the engine during the GDI mode. A fuel system monitor is configured to monitor the fuel delivery system when operating in the PFI mode, and attribute any fuel delivery system malfunctions occurring during the PFI mode to the PFI system alone, and monitor the fuel delivery system when operating in the GDI mode, and attribute any fuel delivery system malfunctions occurring during the GDI mode to the GDI system alone.

Abstract: A port and direct fuel injection (PDI) fuel delivery system for a vehicle having an engine configured to selectively operate between a port fuel injection (PFI) mode, a gasoline direct injection (GDI) mode, and a PDI mode includes a PFI system including plurality of PFI injectors, and a GDI system including a plurality of GDI injectors. The PFI and GDI systems are configured to provide various split-ratios of fuel mass injection to the engine based on a particular engine operating condition. A controller is programmed to identify a known first long term fuel trim (LTFT) for a first split-ratio, identify a known second LTFT for a second split-ratio, generate a linear equation based on the known first and second LTFTs, and determine an unknown third LTFT for a third split-ratio by utilizing the linear equation to facilitate reducing fueling errors and emissions.