National Instruments Direct Injector Driver System Manual
© 2013 National Instruments. All rights reserved.
3.3.3.2 Port Fuel Injectors to PFI Channels
The DI Driver System supports an optional PFI Driver module. The PFI Driver module has four channels, PFI1 –
PFI4, for driving port fuel injectors. Each PFI driver channel is capable of driving low or high impedance port fuel
injectors.
Driving Low Impedance Injectors
Low impedance injectors will have approximately 2 ohms resistance across the solenoid. The low resistance allows
higher current through the solenoid to enable faster valve opening times. However, the high current is not needed for
the entire duration of the injection event in order to keep the valve open. The initial current level is referred to as the
peak current phase and the current level for the remaining injection duration is referred to as the hold current phase.
Typically, the peak current phase is 4A and the hold current phase is 1A.
Driving High Impedance Injectors
High impedance injectors will have approximately 12 ohms resistance across the solenoid. Typically, less than 1
amp is required to open and hold the solenoid valve. Only one current control phase is required to operate high
impedance injectors at a constant current level.
Refer to the
for detailed information on configuring PFI Driver channels.
Wiring diagram for up to four port fuel injectors to the PFI channels of the PFI Driver module is shown in diagram
3.3.3.2.a. (NI recommends using 18 AWG wire (or larger) for port fuel injectors.)