Exam 30: Electronic Fuel Injection

Explain the basic operation of a CPI system.

Technician A says the fuel pressure regulator in a PFI system senses manifold vacuum and continually adjusts the fuel pressure to maintain a constant pressure drop across the injector. Technician B says the pressure regulator in a PFI system is designed to provide a constant pressure to the fuel injector throughout the range of engine loads and speeds. Who is correct?

Technician A says an air/fuel ratio sensor responds to minor changes in the air/fuel mixture. Technician B says that when an air/fuel ratio sensor is used on an OBD-II vehicle, both the upstream and downstream sensors must be air/fuel ratio type sensors. Who is correct?

Technician A says in a returnless fuel system, the pressure regulator is mounted on the fuel rail. Technician B says in a returnless fuel system the pressure regulator, fuel sender, and pump assembly are combined in one unit inside the fuel tank. Who is correct?

To meet OBD II regulations, an updated version of the central port injection (CPI) system uses individual injectors for each poppet nozzle. This system, called central sequential fuel injection (CSFI) allows each injector to be shut off in the event of a misfire.

During closed loop engine mode, injector pulse width is controlled according to predetermined parameters held in the PCM's memory.

Each fuel injector has a _____-wire connector.

In TBI, MFI, and SFI systems, the fuel pressure must be high enough to prevent fuel ____________________.

Define fuel injection.

The throttle body of a port fuel injected engine may include any of the following components EXCEPT:

Which sensor synchronizes the firing of the injectors and determines when piston number 1 is on the compression stroke?

If the throttle is held wide open while the engine is cranked over by the starter motor, the fuel management system will enter _____ mode.

Today the most commonly used EFI system is the mass airflow (MAF) system. This system relies on a MAF sensor that directly measures the amount of intake air.

While discussing central port injection (CPI), Technician A says the poppet nozzles are opened by the computer. Technician B says the poppet nozzles are opened by fuel pressure. Who is correct?

A sudden increase in TP voltage tells the PCM to _____ to prevent hesitation and stumbling during acceleration.

What is meant by sequential firing of fuel injectors?

Identify the some of the advantages of gasoline direct injection (GDI) systems.

While cranking a fuel injected engine and holding the accelerator to the wide-open throttle position, the air/fuel mixture will be ______.

Technician A says the air/fuel ratio of a GDI [gasoline direct injection] engine can be as high as 60 to 1. Technician B says because the air/fuel ratios are so lean, GDI engines require lower compression ratios to prevent detonation. Who is correct?

The high-pressure fuel pump used in GDI [gasoline direct injection] is driven by the ____________________.