Exam 30: Electronic Fuel Injection

To prevent fuel boiling in the TBI assembly, the fuel pressure is kept high.

What is the difference between open loop and closed loop mode?

Explain the major differences between throttle body injectors and port fuel injectors.

Fuel injectors may be controlled ______.

Fuel trim is being discussed. Technician A says a positive fuel-trim value means the PCM detects a lean mixture and is increasing the pulse width to add more fuel to the mixture. Technician B says LTFT [long-term fuel trim] is erased when the ignition is turned off. Who is correct?

When does a GDI [gasoline direct injection] system run in lean burn mode?

Name three advantages of a throttle-by-wire [ETC] system.

Fuel trim can be monitored for diagnostic purposes.

Name five sensors that are used by the PCM to determine the proper injector pulse width.

Technician A says piezoelectric injectors rely on stacked crystals that expand when a voltage is applied. Technician B says piezoelectric injectors are slower acting than solenoid-type injectors. Who is correct?

The throttle stop screw on modern throttle bodies is used to adjust the idle speed.

GDI [gasoline direct injection] systems allow engines to run at very lean air/fuel ratios and eliminate the need for EGR systems.

____________________ systems inject gasoline directly into the cylinders.

The length of time an injector is energized is called the ____________________ width.

In a GDI system, the fuel is injected at pressures above ____________________ psi.

Why are SFI injection systems required on modern vehicles?

Explain how the computer controls the air/fuel ratio on an EFI system during closed loop.

Fuel injectors are ______.

The ____________________ in a PFI system controls the amount of air that enters the engine as well as the amount of vacuum in the intake manifold.

While discussing PFI systems, Technician A says the PCM provides the proper air/fuel ratio by controlling the fuel pressure. Technician B says the PCM provides the proper air/fuel ratio by controlling the injector pulse width. Who is correct?