Exam 30: Electronic Fuel Injection

Technician A says an SFI is more efficient than an MPI injection because fuel is injected only when the intake valve is open, so the fuel can't condense when the intake valve is closed. Technician B says an MPI injection system can shut down the injector for a misfiring cylinder, preventing catalytic converter overheating. Who is correct?

Which of the following is NOT a component of a throttle-by-wire system?

____________________ systems inject fuel above the throttle plates.

Technician A says when the ECT sensor detects low engine temperature, the PCM decreases the injection pulse width. Technician B says when the TP sensor detects a sudden increase in throttle angle, the PCM increases the injectors' pulse width. Who is correct?

The auxiliary air valve is controlled by the PCM.

In most TBI systems, the fuel pressure is maintained at _____.

Because modern engines heat up rapidly, heated oxygen sensors (HO₂S) are not needed.

A speed-density EFI system computer determines the amount of air entering the engine from the ____________________ sensor and engine rpm input signals.

Technician A says the vacuum hose on the fuel pressure regulator of a PFI system is connected to the intake manifold. Technician B says the fuel pressure regulator of a TBI injection system doesn't need a vacuum hose to regulate pressure because the injectors are located above the throttle plate where the air pressure is constant. Who is correct?

The fuel pressure regulator can be located _____.

Describe the purpose of a manifold absolute pressure (MAP) sensor.

The injectors on a modern port fuel injection system receive fuel from the ____________________.

Fuel injector firing is being discussed. Technician A says SFI systems control each injector separately so that it fires just before the intake valve opens. Technician B says sequential injector firing is more accurate than multiport systems. Who is correct?

A mass airflow-type fuel injection system uses a ____________________ sensor to determine the amount of air entering the engine.