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AEP > hw 7,8 > Flashcards

hw 7,8 Flashcards

1
Q

A disconnected vacuum hose on a fuel pressure regulator may cause excessive fuel pressure.

A

True’.

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2
Q

SFI is a type of PFI fuel system.

A

True’.

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3
Q

Inertia switches open the fuel pump circuit in case of a severe impact.

A

True

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4
Q

Fuel system pressure should be relieved with the engine running.

A

False

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5
Q

The octane number indicates the antiknock quality of gasoline.

A

True’

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6
Q

Throttle body fuel injection systems provide improved fuel metering when compared to:

A

Carburetors

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7
Q

Technician A says fuel that has low volatility can cause a buildup of deposits in the combustion chamber. Technician B says liquid gasoline will not burn. Who is correct?

A

Both A and B

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8
Q

When the pressure in the intake manifold increases the fuel pressure regulator on a port fuel injection system:

A

Increases fuel pressure

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9
Q

The acceptable amount of alcohol mixed with gasoline is

A

Up to 15%

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10
Q

Technician A says to relieve pressure on an EFI system, a pressure gauge may be connected to the fuel pressure test port and the bleed valve on the gauge opened with the bleed hose installed in an approved container. Technician B says before fuel system components on an EFI system can be removed, the fuel system pressure must be relieved. Who is correct?

A

Both A and B

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11
Q

Technician A says the fuel rail delivers fuel to the fuel injectors. Technician B says the throttle body in a port fuel injection system controls the amount of fuel entering the engine. Who is correct?

A

Technician A only

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12
Q

The fuel pressure regulator in a typical mechanical returnless fuel system is located:

A

At the fuel pump sender assembly

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13
Q

Technician A says a rich air-fuel mixture may be the result of higher-than-normal fuel pressure. Technician B says higher-than-normal fuel pressure causes a lean air-fuel ratio. Who is correct?

A

Technician A only

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14
Q

High fuel pressure may be caused by a:

A

Defective fuel pressure regulator/Fuel return line that is restricted

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15
Q

Technician A says low fuel pressure may be caused by a restricted fuel filter. Technician B says when testing fuel pressure, make sure the specifications are either for the engine running or the engine off. Who is correct?

A

Both A and B

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16
Q

Discussing a multi-port injected system: Technician A says the powertrain control module provides the proper air-fuel ratio by controlling injector pulse width. Technician B says the powertrain control module controls the fuel pressure to provide the proper air-fuel ratio. Who is correct?

A

Technician A only

17
Q

Technician A says that if the engine stalls and the ignition switch is on, the one-way check valve prevents fuel flow from the pump to the fuel filter and fuel system. Technician B says that when the engine is shut off, the one-way check valve prevents fuel flow from the under-hood fuel system components into the fuel pump and tank. Who is correct?

A

Technician B only

18
Q

Technician A says reducing spark advance can cause spark knock. Technician B says excessive carbon deposits can cause spark knock. Who is correct?

A

Technician B only

19
Q

All of the following are added to gasoline today except?

A

Tetraethyl lead

20
Q

Direct gasoline injection systems can spray fuel directly into the combustion chamber when the intake valve is opened.

A

True

21
Q

The idle air control (IAC) valve controls the amount of fuel entering the engine to maintain proper idle speeds.

A

False

22
Q

Central multiport fuel injection systems use one injector and separate fuel tubes that run to each cylinder.

A

True

23
Q

MAP sensors read any pressure above a perfect vacuum.

A

True

24
Q

The intake manifold turning valve (IMTV) makes the intake manifold an active manifold, that is, it responds to changing demands.

A

True

25
Q

Long term fuel trim will change in an attempt to keep short term fuel trim near 0.

A

True

26
Q

An air-fuel ratio sensor does a better job than an O2 sensor of determining just how rich or lean an engine is running.

A

True

27
Q

Clogged fuel injectors will cause long term fuel trim to take away fuel.

A

False

28
Q

Technician A says if the IAC value is at or near zero on a speed density system there may be a manifold vacuum leak. Technician B says if the IAC value is too high there may be a build-up of carbon on the backside of the throttle plate. Who is correct?

A

Both A and B

29
Q

To help isolate a clogged or dirty injector

A

Perform an injector balance test

30
Q

Technician A says acceleration stumbles may be the result of restricted injector tips. Technician B says cylinder misfiring at idle speed may be caused by a defective injector. Who is correct?

A

Both A and B

31
Q

Injector pulse width is

A

The amount of time the injector is turned on

32
Q

Technician A says the poppet nozzles in the CMFI system are opened by fuel pressure. Technician B says the computer opens the poppet nozzles in the CMFI system. Who is correct?

A

Technician A only

33
Q

Technician A says a speed density EFI system is one in which the computer calculates the amount of air entering the engine. Technician B says that to determine the air entering the engine in a speed-density system, the computer uses the TPS and ECT signals. Who is correct?

A

Technician A only

34
Q

The purpose of the manifold vacuum connection to the fuel pressure regulator is to

A

Maintain the same pressure drop across the injectors at idle speed and wide-open throttle

35
Q

Technician A says higher fuel pressure at wide-open throttle is the result of low manifold vacuum to the pressure regulator in the SFI system. Technician B says higher fuel pressure at wide-open throttle is maintained by the PCM in the SFI system to enrich the air/fuel ratio for better acceleration. Who is correct?

A

Technician A only

36
Q

Technician A says coolant is routed through the throttle body to warm the incoming air. Technician B says the throttle body is warmed by coolant to prevent it from freezing. Who is correct?

A

Technician B only

37
Q

Multiport fuel injection systems do not require a

A

Camshaft position sensor

38
Q

Technician A says a SFI requires both crank and cam position sensors. Technician B says SFI engines can also function as MFI if necessary. Who is correct?

A

Both A and B

39
Q

Technician A says an injector ohm test is the most accurate method of testing a fuel injector’s operation. Technician B says an injector ohm test can only confirm a defective injector winding. Who is correct?

A

Technician B only

AEP (5 decks)

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