Electronic Unit Injectors

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Questions and Answers

What is the function of an electronic unit injector (EUI)?

  • Controls the fuel injection timing
  • Meters, pressurizes, and injects fuel directly into the combustion chamber (correct)
  • Adjusts the airflow in the combustion chamber
  • Regulates the exhaust gas recirculation

What is a key advantage provided by Electronic Unit Injectors (EUIs)?

  • Increased turbocharger efficiency
  • Lower fuel consumption
  • Higher injection and spray-in pressure (correct)
  • Reduced exhaust gas temperature

What drives the unit injector in an engine with overhead cam-driven EUIs?

  • A dedicated camshaft lobe (correct)
  • A fuel pump
  • A rocker lever
  • An electric motor

What is the primary role of the poppet valve or spill control valve in a conventional unit injector?

<p>Regulates the buildup of pressure inside the injector (B)</p> Signup and view all the answers

What is the purpose of the electric solenoid or cartridge valve in a unit injector?

<p>Controls the movement of the poppet valve (B)</p> Signup and view all the answers

What is the fuel pressure range for the newest EUIs, such as the Delphi E3 electronic unit injector?

<p>35,000-38,000 psi (D)</p> Signup and view all the answers

What are the service advantages of Electronic Unit Injectors (EUIs)?

<p>Adjustment-free design (B)</p> Signup and view all the answers

What prevents fuel leakage in a conventional unit injector?

<p>O-rings on the injector (D)</p> Signup and view all the answers

What is the purpose of the spring-loaded plunger and barrel assembly in a unit injector?

<p>Pressurizes fuel inside the injector (C)</p> Signup and view all the answers

What is the function of the nozzle valve in a unit injector?

<p>5-13 orifice holes with NOP of 3500-5000 psi (C)</p> Signup and view all the answers

What is the role of the solenoid-actuated, electronically controlled spill valve in an electronic unit injector (EUI)?

<p>Energizes the spill valve (C)</p> Signup and view all the answers

What drives the injector in an engine with overhead cam-driven EUIs, resulting in the least amount of injection lag?

<p>Overhead camshaft (D)</p> Signup and view all the answers

What is the primary function of an electronic unit injector (EUI)?

<p>Meters, pressurizes, and injects fuel directly into the combustion chamber (B)</p> Signup and view all the answers

What is the purpose of the electric solenoid or cartridge valve in a unit injector?

<p>Controls the movement of the poppet valve (A)</p> Signup and view all the answers

What is the fuel pressure range for the newest EUIs, such as the Delphi E3 electronic unit injector?

<p>35,000-38,000 psi (A)</p> Signup and view all the answers

What is a key advantage provided by Electronic Unit Injectors (EUIs)?

<p>Higher injection and spray-in pressure (D)</p> Signup and view all the answers

What is the purpose of the spring-loaded plunger and barrel assembly in a unit injector?

<p>Pressurizes fuel inside the injector (C)</p> Signup and view all the answers

What is the primary role of the poppet valve or spill control valve in a conventional unit injector?

<p>Regulates the buildup of pressure inside the injector (D)</p> Signup and view all the answers

What is the role of the solenoid-actuated, electronically controlled spill valve in an electronic unit injector (EUI)?

<p>Energizes the spill valve (A)</p> Signup and view all the answers

What are the service advantages of Electronic Unit Injectors (EUIs)?

<p>Faster repair times (C)</p> Signup and view all the answers

What drives the unit injector in an engine with overhead cam-driven EUIs?

<p>Dedicated camshaft lobe (A)</p> Signup and view all the answers

What is the function of the nozzle valve in a unit injector?

<p>Produces fine spray with multiple orifice holes (A)</p> Signup and view all the answers

What prevents fuel leakage in a conventional unit injector?

<p>O-rings on the injector (A)</p> Signup and view all the answers

What drives the injector in an engine with overhead cam-driven EUIs, resulting in the least amount of injection lag?

<p>Dedicated camshaft lobe (A)</p> Signup and view all the answers

What regulates the injection timing and quantity of fuel in an electronic unit injector (EUI)?

<p>ECM (A)</p> Signup and view all the answers

What happens when the solenoid valve of the unit injector is energized?

<p>Injector plunger pressurizes the fuel (D)</p> Signup and view all the answers

What is the primary function of the spill control valve in a unit injector?

<p>Regulate fuel injection timing and quantity (D)</p> Signup and view all the answers

What drives the injector plunger in an engine with overhead cam-driven EUIs?

<p>Camshaft (D)</p> Signup and view all the answers

What occurs when the solenoid of the unit injector is deenergized?

<p>Poppet valve opens, allowing fuel to drain back (B)</p> Signup and view all the answers

What is the role of the nozzle valve in a unit injector during fuel injection?

<p>Opens to allow pressurized fuel to enter the combustion chamber (B)</p> Signup and view all the answers

What is the purpose of the fuel rail in a unit injector system?

<p>Supply consistent fuel temperature between injectors (B)</p> Signup and view all the answers

What is the function of the low-pressure fuel supplied to the injector during the suction stroke?

<p>Fills the cavity created beneath the plunger (C)</p> Signup and view all the answers

What is the role of the pressurized fuel in a unit injector system?

<p>Forces the nozzle valve open for fuel injection (C)</p> Signup and view all the answers

What is the significance of the energization time of the solenoid in a unit injector system?

<p>A longer electrical signal generally translates into more fuel injected (B)</p> Signup and view all the answers

What happens during the residual stroke in a unit injector system?

<p>Fuel trapped beneath the plunger drains back (D)</p> Signup and view all the answers

What is the effect of speed increase on the timing of actuating the solenoid in a unit injector system?

<p>Timing needs to be delayed as speed increases (B)</p> Signup and view all the answers

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