Exam 31: Fuel Injection System Diagnosis and Service

An oxygen sensor must heat up to approximately _____ before functioning in its closed loop mode.

What is the difference in signal output between an oxygen sensor and an A/F [air/fuel] ratio sensor?

The LTFT works to bring the STFT close to a 0 percent correction.

With the TP sensor connector disconnected, test the sensor with a(n) ____________________.

A(n) ____________________ is used to test the internal electrical circuit of an injector.

Do not use compressed ____________________ to flush or clean the fuel rail.

Other than inspecting the electrical connections, there are usually no physical checks to mass airflow or manifold absolute pressure sensors.

Idle learn procedures for ETC [throttle-by-wire]-equipped vehicles are being discussed. Technician A says the learn or relearn procedure should be completed anytime the PCM has been replaced or updated, or after the throttle body has been cleaned or replaced. Technician B says the system does not need to relearn if the battery has been disconnected. The system will automatically go through the procedure when the engine is restarted.Who is correct?

An exhaust gas analyzer can be used to determine whether an injector is leaking.

Technician A says a defective injector may cause cylinder misfiring at idle speed. Technician B says restricted injector tips may result in acceleration stumbles. Who is correct?

STFT adjustments are temporary and are not stored in the PCM's memory.

Always pressurize the fuel system before disconnecting any fuel system components.

IAC motor damage may result if throttle body cleaner is allowed to enter the motor.

Quick tests to a GM hot film mass airflow meter on an engine with idling problems are being performed. Technician A taps on the meter lightly with a plastic mallet. Technician B unplugs the meter. Who is correct?

The engine must be at normal operating temperature before the O₂ sensor is tested.

If a hot-wire type mass airflow [MAF] sensor is contaminated with dirt, the operation of the ____________________ relay should be checked.

How is an injector balance test performed?

What is the difference between the pulse width of an injector and the duty cycle?

Which of the following components can cause excessively high pressure in a returnless fuel delivery system?

Fuel trim is being discussed. Technician A says a + 12.0 percent LTFT value indicates that the system is running 12 percent richer than normal. Technician B says LTFT should constantly change between positive and negative values when the system is running in closed loop. Who is correct?