30 Questions
What is the major difference between the Detroit Diesel N3 and E3 injectors?
The N3 uses a single compact electromagnetic solenoid while the E3 uses two
What technology is not easily accomplished electronically in EUIs?
Rate shaping
What does a low-mass nozzle control valve (NCV) do in the Detroit Diesel N3 injector?
Tip the balance of high-pressure fuel acting above and below the valve
What is the purpose of the pump section in the N3 and E3 unit injectors?
Consists of a camshaft-operated plunger operating inside a barrel
What method can be used to calculate injector response times?
ECM detects when the poppet valve closes
What could wide variations in response time for one injector at a steady engine rpm indicate?
An electrical problem
What could cause injector codes?
Short circuit
What does the ECM use to detect the start of delivery and time the next injection event?
Voltage drop created when the poppet valve closes
What do PWM signals do?
Vary the amount of time they are on or off
What is used to prevent the formation of emissions in an engine's cylinders?
Better EUI design
What is the purpose of a pull test in electronic signal processing?
To check for defective wiring and poor connections
What does a change in fault code counts typically indicate when using service software?
Issues with circuit and not the component
What should be checked if two or more injectors are misfiring and have Low Current codes?
Ground return circuit for open or resistive circuits to the ECU
What is the strategy of tracking time variations between the voltage drops for each injection called?
Injector response time
What does a lengthening of individual injector response times indicate?
Different resistances or bad connectors
What is the purpose of a pull test in electronic signal processing?
To check for defective wiring and poor connections
What does a change in fault code counts typically indicate when using service software?
Issues with circuit and not the component
What should be checked if two or more injectors are misfiring and have Low Current codes?
Ground return circuit for open or resistive circuits to the ECU
What is the strategy of tracking time variations between the voltage drops for each injection called?
Injector response time
What does a lengthening of individual injector response times indicate?
Different resistances or bad connectors
What is a key feature of the N3 injector?
Hydraulically balanced nozzle valve
What distinguishes the Delphi E3 injector from other unit injectors?
Superior rate-shaping abilities
What technology does the Delphi E3 injector use for regulating injection pressure, timing, and metering events?
Dual valves (NCV and SCV)
What is the maximum spray-in pressure that the N3 injector can reach?
35,000 psi
What stage involves the injector plunger drawing fuel from the cylinder head fuel rail?
Filling stage
What allows pressurized fuel to spray into the combustion chamber during the injection stage?
Energized NCV
What is the purpose of the deenergized SCV coil at the end of injection?
To open the spill control valve
What design feature of the Delphi E3 injector enables high-pressure fuel to close the nozzle at the end of the injection event?
Double-pulse design
What is a benefit of the Delphi E3 injector over other EUIs?
Programmable, variable-pressure nozzle opening and closing
What is involved in the pressurization stage of the injector operation?
Moving the injector plunger downward
Study Notes
Diesel Fuel Injector Technology Overview
- The N3 injector features a hydraulically balanced nozzle valve that is opened and closed with pressurized fuel, and its compact, electrically operated hydraulic control valves allow for faster injection events.
- The N3 injector can reach spray-in pressures of up to 35,000 psi, and its unique double-pulse design enables high-pressure fuel to close the nozzle at the end of the injection event.
- The Delphi E3 injector, introduced for 2002 EGR equipped, diesel engines, uses a dual-control valve, four-wire, two-solenoid design that can electronically change injection pressure from 5000 to 37,000 psi.
- The Delphi E3 injector has features that enable it to provide superior rate-shaping abilities compared to other unit injectors, and it was one of two remaining fuel injection systems in use for HD on-road engines until 2017, when only common rail systems were used.
- Benefits of the Delphi E3 injector over other EUIs include high-speed, dual-valve operation, programmable, variable-pressure nozzle opening and closing, ultra-high-injector pressure, lightweight, compact design, and 621,000 mile (1,000,000 km) durability.
- The Delphi E3 injector uses two valves, a normally closed NCV and a normally open SCV, to regulate injection pressure, timing, and metering events, and its operation involves a filling stage, pressurization stage, injection stage, and end of injection stage.
- During the filling stage, the injector plunger moves upward and draws fuel from the cylinder head fuel rail, and if the injector is not energized, it results in a waste stage of plunger movement.
- In the pressurization stage, the injector plunger is moved downward, and no pressurization can take place until the SCV closes, trapping fuel beneath the plunger and increasing fuel pressure.
- During the injection stage, fuel pressure is applied to the bottom of the nozzle valve, and when the NCV is energized, it opens and allows pressurized fuel to spray into the combustion chamber.
- At the end of injection, the deenergized SCV coil allows a beveled washer-like spring to open the spill control valve, permitting fuel trapped below the injector plunger to pass to a fuel return circuit, and the NCV is de-energized to allow fuel pressure to rebuild and hydraulically close the valve.
Test your knowledge of diesel fuel injector technology with this quiz. Learn about the features and benefits of N3 and Delphi E3 injectors, their operation stages, and their capabilities in high-pressure fuel injection systems.
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