Exam 30: Electronic Fuel Injection

Nearly all of today's diesel systems have a common rail injection system in which the injectors are directly controlled by the PCM.

The ____________________ helps to maintain constant fuel pressure, reduces fuel noise, and maintains pressure during engine cool down.

Typical fuel injector pulse widths range from _____ to _____ milliseconds.

Technician A says throttle-by-wire systems [ETC] eliminate the need for a cruise control actuator. Technician B says ETC also allows the PCM to be more effective when limiting engine and vehicle speeds. Who is correct?

Technician A says TBI systems use top fuel-feeding injectors. Technician B says PFI systems use bottom fuel-feeding injectors. Who is correct?

Identify the purpose and two designs of mass airflow sensors.

The ____________________ system controls idle speed by opening and closing a bypass passage in the throttle body in response to commands from the PCM.

MAP output is the same as what is measured on a vacuum gauge. When intake vacuum is high, MAP voltage is high.

Technician A says the oxygen sensor (O₂S) detects misfires by monitoring the amount of unburned fuel in the exhaust system. Technician B says a heating element inside the sensor allows the sensor to reach operating temperature quickly and to maintain its temperature during periods of idling or low engine load. Who is correct?

Technician A says pulsation dampers reduce the pressure pulsations caused by the rapid opening and closing of the fuel injectors. Technician B says the damper helps to reduce fuel noise and maintains pressure during engine cooldown. Who is correct?

Technician A says in order to meet OBD standards, diesel control systems use many of the same inputs as a gasoline engine (such as the MAP, IAT, MAF, TP, CKP, and CMP sensors). Technician B says the pressure in the fuel rail of a modern common rail diesel engine can range from 2,000 psi (138 bar) to 25,000 psi (1,724 bar). Who is correct?

In a GDI [gasoline direct injection] system, the tip of the injector is located ______.

OBD-II systems have only one O₂S [oxygen sensor] in the exhaust system, located after the catalytic converter (downstream).

The ideal, or stoichiometric mixture of air and fuel for a gasoline engine is ____________________ to 1.

The IAC system uses a ____________________ motor to retract or extend the IAC valve.

The mass airflow (MAF) sensor measures changes in the intake manifold pressure that result from changes in engine load and speed.

The PCM may order a richer mixture when the engine is overheating.

Idle speed control is a function of the PCM.

A fuel injection system that uses a MAP sensor [manifold absolute pressure] to determine the amount of air entering the engine is called a _____-type injection system.

An O-ring at the base of a fuel injector ______.