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</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</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</p> Signup and view all the answers

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

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

    What prevents fuel leakage in a conventional unit injector?

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

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

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

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

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

    What prevents fuel leakage in a conventional unit injector?

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

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

    <p>ECM</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</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</p> Signup and view all the answers

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

    <p>Camshaft</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</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</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</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</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</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</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</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</p> Signup and view all the answers

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