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Fuels > quiz 3 > Flashcards

quiz 3 Flashcards

1
Q

In a HPCR fuel system, fuel output pressure to the injectors is controlled by:

pump speed and flow.

the rail pressure control valve.

common rail and injector line volume.

the pressure limiting valve.

A

the rail pressure control valve.

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2
Q

Injection in a hydraulically controlled electronically activated injector may be classified as:

a constant beginning and variable end.

a constant beginning and end.

a variable beginning and end.

a variable beginning and constant end.

A

a variable beginning and end.

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3
Q

Injection timing is changed, on electronic controlled diesel engines, primarily by information received from the:

Fuel pressure sensor.

electronic unit injectors.

oil pressure sensor.

engine speed sensor.

A

engine speed sensor.

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4
Q

“HEUI” is an acronym for:

Heated Encapsulated Unit Injector.

High Efficiency Unit Injector.

Hydraulically Actuated Electronically Controlled Unit Injector.

High Energy Unit Injector.

A

Hydraulically Actuated Electronically Controlled Unit Injector.

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5
Q

The ECM would ____________ the PWM signal to the injection actuation pressure control valve during start up.

decrease

increase

encode

decode

A

increase

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6
Q

The HEUI fuel system controls engine cylinder injection pressures by:

control is built into the injectors using orifices and accumulators.

ECM control of the primary fuel system pressure.

ECM control of the fuel pressure prior to the injectors.

ECM control of oil pressure directed to an amplifier piston.

A

ECM control of oil pressure directed to an amplifier piston.

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7
Q

The HPCR fuel system utilizes a radial piston pump that provides high pressure:

mechanical actuation force.

oil for the injection process.

fuel for the transfer process.

fuel for the injection process.

A

fuel for the injection process.

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8
Q

A coolant level sensor on the C-12 engine would most likely be used by the ECM for the purpose of:

fuel delivery schedule.

timing schedule.

engine shutdown system.

torque curve shaping.

A

engine shutdown system.

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9
Q

Which of the following statement(s) is/are true?

Diagnostic fault codes are provided to indicate an electrical/electronic problem has been detected by the ECM.

Flash codes are the same for all engines.

Diagnostic event codes are provided to indicate some operational problem and usually does not indicate an electronic malfunction.

Both a. and c. are correct.

A

Both a. and c. are correct.

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10
Q

A grounded signal wire at a temperature sensor would result in:

a burnt harness.

a zero volt signal at the ECM.

a five volt signal at the ECM.

damage to the five volt regulator.

A

a zero volt signal at the ECM.

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11
Q

The outputs of an electronic control system may be classified as:

sensors and actuators.

actuators and displays.

displays and sensors.

proportional and variable.

A

actuators and displays.

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12
Q

A temperature sensor in which the resistance value decreases as the temperature increases can be considered a:

negative temperature co-efficient resistor.

duty cycle resistor.

positive temperature co-efficient resistor.

pulse width modulated resistor.

A

negative temperature co-efficient resistor.

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13
Q

The limp home mode will usually:

energize the pull-in winding.

reduce engine speed to a pre-determined amount.

shut the engine down.

maintain normal running.

A

reduce engine speed to a pre-determined amount.

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14
Q

For use by a microcomputer, electrical analog voltage signals are:

reduced to digital signals.

amplified to digital signals.

encoded to digital signals.

decoded to digital signals.

A

encoded to digital signals.

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15
Q

The percentage of time a solenoid is energized relative to the total cycle time is the:

pulse width modulation.

duty cycle.

amplitude.

frequency.

A

duty cycle.

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16
Q

A thermistor is best described as a component:

that is a thermally sensitive resistor.

with a positive resistance coefficient of temperature.

with a digitally controlled resistance valve.

that is a thermally sensitive switch.

A

that is a thermally sensitive resistor.

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17
Q

The duration of time that the solenoid is energized can be expressed as:

pulse width modulation.

PWM or Duty Cycle

frequency.

duty cycle.

amplitude.

A

PWM or Duty Cycle

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18
Q

An analog signal is a wave form that can change in _____________.

amplitude only.

frequency only.

mean effective voltage.

amplitude and frequency.

A

amplitude and frequency.

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19
Q

A two wire temperature sensor with an open ground wire would be read by the ECM as:

high voltage.

high resistance.

high current.

low current.

A

high voltage.

20
Q

Before reaching a sensor, the current from the ECM power supply passes through a current limiting resistor for the purpose of:

decoding within the ECM.

preventing excess current flow.

preventing excess resistance.

encoding within the ECM.

A

preventing excess current flow.

21
Q

When attempting to communicate with an ECM, via its data link port, a technician must:

have the appropriate software loaded on a “PC”.

have the appropriate interface between the ECM and the “PC”.

have the ignition key turned on.

all of the above answers are correct.

A

all of the above answers are correct.

22
Q

If a reluctance type of sensor does not generate a strong signal, our first check should be:

resistance of the sensor winding.

charging system and battery voltage.

sensor clearance to the pulse wheel tabs.

voltage of the sensor input line.

A

sensor clearance to the pulse wheel tabs.

23
Q

A customer programmable feature on a 3406E engine would likely be stored in the:

EEPROM.

RAM.

ROM.

PROM.

A

EEPROM.

24
Q

The SAE code system uses the FMI to describe a code. This stands for:

failure module identifier.

for module information.

failure mode identifier.

further maintenance identification.

A

failure mode identifier.

25
Q

An out-of-range sensor would be displayed by the ECM as a fault code. This would be considered:

a hard (active) code.

a soft (inactive) code.

a historic code.

both b. and c.

A

a hard (active) code.

26
Q

A diagnostic fault code that would likely cause the ECM to put the engine in a de-rate mode (limp home) could be received from the following sensors except the:

oil pressure sensor.

coolant level sensor.

vehicle speed sensor.

engine speed/timing sensor.

A

vehicle speed sensor

27
Q

A potentiometer type of throttle position sensor provides the ECM with a:

varying resistance reading.

current flow signal.

AC analog signal.

DC analog signal.

A

DC analog signal.

28
Q

The process of converting a digital signal to an analog signal is commonly referred to as:

decoding.

pulse width modulation.

encoding.

duty cycle.

A

decoding.

29
Q

A coolant temperature sensor has a specification range of 3,000 to 4,000 ohms. The measured resistance of the sensor is 12K ohms. This indicates that the sensor:

is in good condition.

has high resistance.

has an open winding.

as an internal short.

A

has high resistance

30
Q

The speed of a 3126B engine is calculated by the ECM from the:

voltage of the signal received.

frequency of the signal received.

duration of the signal received.

amplitude of the signal received.

A

frequency of the signal received.

31
Q

Electronically controlled fuel injection systems:

optimize engine performance.

lower exhaust emissions.

reduce fuel consumption.

improve start ability.

all of the above are correct.

A

all of the above are correct.

32
Q

An injector solenoid tested with an ohmmeter reads below specifications. It may be said the solenoid:

has excessive resistance.

has an open circuit.

has a ground fault.

has a short circuit.

A

has a short circuit.

33
Q

An analog signal can be defined as one which is a(n):

varying DC voltage.

AC sine wave.

both a. and b. are correct.

constant PWM voltage.

A

both a. and b. are correct

34
Q

During engine operation the computer would read the ___________ across the thermistor.

voltage drop

resistance

analog signal

current flow

A

voltage drop

35
Q

A reluctance type sensor may be used by the ECM for:

engine RPM.

engine speed.

camshaft position.

all the above.

A

all the above.

36
Q

The Cat C-15 electronic unit injector control signal is:

adjusted by the fuel position sensor.

buffered by the throttle position sensor.

obtained directly from the timing sensor.

pulse width modulated by the ECM.

A

pulse width modulated by the ECM.

37
Q

A fault code is generated if a sensor’s output is:

below 5 volts.

digital.

not within acceptable parameters.

below 8 volts.

A

not within acceptable parameters.

38
Q

A fault code may be displayed as a(n):

flashing panel lamp.

illuminated panel display symbol.

numeric code, displayed on a service tool.

all of the above answers are correct.

A

all of the above answers are correct

39
Q

The reluctance type of sensor generates:

a digital DC signal.

an AC voltage signal.

an analog DC signal.

none of the above are correct.

A

an AC voltage signal.

40
Q

An actuator is an output device that receives a signal from:

the accelerator sensor.

a variety of sensors.

the speed sensor.

the electronic control module.

A

the electronic control module.

41
Q

A three wire throttle position sensor may be classified as:

a proportional potentiometer.

an input device.

both a. and b. are correct.

an output signal.

A

both a. and b. are correc

42
Q

When checking electronic circuits, it is important that the voltmeter used have:

low impedance.

high impedance.

high capacitance.

low resistance.

A

high impedance.

43
Q

The following can be considered transducers, except:

a transformer.

a coolant level sensor.

an accelerator position sensor.

a boost pressure sensor.

A
44
Q

A C-12 electronic unit injector will deliver fuel to the engine when the solenoid is:

does not need current.

de-energized.

open.

energized.

A

energized.

45
Q

Diagnostic trouble codes generated by the ECM are considered:

amplitude type signals.

output signals.

frequency type signals.

input signals.

A

output signals.

Fuels (4 decks)

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