PFI/Di Electrical Failure Mode And Effects Management

DI Injector/Circuit Failure: 

If a DI fuel injector fails, fuel injection for that cylinder (both PFI and DI) will be disabled. Some failures, such as shorts to ground on the low side, require the control system to disable a pair of DI injectors due to a common high side control circuit. In those cases, two cylinders will be disabled. The rationale for this FMEM action is because combustion without DI injection will damage the DI injector due to injector over temperature.

PFI Injector/Circuit Failure: 

If a PFI fuel injector fails, all PFI injectors will be disabled. The rationale for this is a control system constraint. The fuel fraction delivered by each system (PFI or DI) is calculated on a "per engine" basis, not an individual cylinder basis. Disabling one PFI injector would require a second set of fueling calculations. For simplicity sake, if any PFI failure exists, engine operation will switch to DI only.

DI High Pressure Fuel Pump Circuit Failure: 

If the DI high pressure fuel pump fails, the control system will run the engine using the PFI system, with the inclusion of some DI operation for DI injector maintenance. The DI system will be forced to operate at lift pump pressures but the PFI system will be fully functional. The DI injections will only be used to cool the DI injectors.