Automotive Exam

timer Asked: Jun 26th, 2018

Question description

Oxides of nitrogen (NOx) contribute to the formation of

A. photochemical smog.

B. acid rain.

C. particulate emissions.

D. high levels of CO2.

Technician A says that a converter that rattles when tapped with a mallet should be replaced. Technician B says that the root cause of a converter failure should be diagnosed and repaired before a replacement converter is installed. Who is correct?

Two technicians are explaining what exhaust gas emissions tell you about engine operation. Technician A says that the higher the level of CO2 in the exhaust stream, the more efficiently the engine is operating. Technician B says that CO2 levels of 20 to 25 percent are considered acceptable.

Technician A says that a 3 × 5 card should be held against the oil fill opening if the positive crankcase ventilation (PCV) system is operating correctly. Technician B says that if a PCV valve rattles, it's working properly. Who is correct?

Oxygen combines with nitrogen in the air to form NOx at about _______ °F.

A. 1500

B. 50

C. 2500

D. 000

A maximum reading of _______ parts per million (PPM) of NOx under loaded driving conditions generally means that the vehicle will pass an enhanced I/M roller test.

A. 1,000

B. 500

C. 100

D. 2,000

Two technicians are discussing the evaporative emission monitor. Technician A says that serious monitor faults cause a blinking malfunction indicator lamp (MIL) or even an engine shutdown. Technician B says that the engine computer will run the EVAP monitor when fuel level is within 15 to 25 percent and the TP sensor position is between 9 and 10 percent. Who is correct?

Technician A says that the location of the catalytic converter isn't important. Technician B says that the catalytic converter should be positioned as far away from the engine as possible. Who is correct?

The OBD-II catalytic converter monitor uses _______ sensor(s) to monitor catalytic converter efficiency.

A. an engine coolant temperature

B. front and rear catalyst temperature

C. front and rear O2

D. a throttle position

A vehicle has a crimped fuel return line. What effect will this have on 5-Gas Analyzer gas readings?

A. CO decreases

B. NOx stays the same

C. O2 increases

D. HC decreases

The _______ valve protects the air pump from reverse-exhaust pressure.

A. check

B. diverter

C. positive crankcase ventilation (PCV)

D. gulp

As the efficiency of the catalytic converter drops through deterioration, the switching rate of the rear O2 sensor signal will start to look like the front O2 sensor signal. When the rear O2 sensor signal reaches approximately 75 percent of the front O2sensor, which of the following is the result?

A. The catalytic converter should be replaced.

B. A one-trip flag is set with a code stored, but the MIL isn't activated.

C. The catalyst beads in the converter should be changed.

D. The diagnostic trouble code is stored with the MIL on.

Which of the following exhaust gases are least likely to be measured in percentages?

A. CO (carbon monoxide)

B. CO2 (carbon dioxide)

C. HC (hydrocarbon)

D. O2 (oxygen)

The positive crankcase ventilation (PCV) system helps reduce _______ exhaust gas emissions.

A. CO2 (carbon dioxide)

B. NOx (oxides of nitrogen)

C. oxygen

D. HC (hydrocarbon)

To avoid excessive catalyst temperatures and the possibility of fuel vapors reaching the converter, the following rules are being discussed: Technician A says that it's okay to use any fuel additives or cleaners in the fuel system. Technician B says that you should repair engine problems such as dieseling, misfiring, or stumbling as soon as possible. Who is correct?

Technician A says that carbon monoxide (CO) and hydrocarbon (HC) levels should increase if the air injection reactor (AIR) hoses are pinched off. Technician B says that a defective drive belt may cause AIR system problems. Who is correct?

What term describes a catalytic converter as it reaches its effective temperature?

A. Initiation

B. Consumption

C. Light-off

D. Firing

Which one of the following is a prime source of problems in secondary air systems?

A. Dirt

B. Water

C. Engine coolant

D. Engine oil

Which of these evaporative control valve(s) is/are normally open?

A. Both the canister purge and canister vent valve

B. Neither the canister purge nor canister vent valve

C. Canister purge valve

D. Canister vent valve

Which of these engine concerns may be caused by a stuck-open exhaust gas recirculation (EGR) valve?

A. Excessive NOx exhaust emissions

B. Ping (spark knock or detonation)

C. Engine missing at highway speed

D. Rough idle/stalling

One of the best ways to find a vacuum leak on a speed-density fuel-injection system is to read the intake air controller (IAC) count, or percentage, with a scan tool. Normal IAC percentage is usually 15 to 25. A reading of less than _______ indicates a vacuum leak.

A. 25

B. 10

C. 15

D. 5

Which of these sensors would be least likely used as an input sensor?

A. Engine-coolant temperature

B. Throttle position

C. Fuel


Technician A says that the powertrain control module (PCM) uses the manifold absolute pressure (MAP) sensor to determine the load on the engine and the amount of fuel needed. Technician B says that, at idle, the MAP sensor voltage will be higher at high altitudes than when at sea level. Who is correct?

The absence of any mechanical linkage between the throttle pedal and the throttle body requires the use of a _______ motor.

A. stepper



D. throttle

A potentiometer is a variable-resistance sensor with _______ terminals.

A. three

B. one

C. two

D. four

A _______ is used to electrically replace the injector in the circuit and flash if the injector circuit is working correctly.

A. noid light

B. 100 ohm resistor

C. 30–40 ohm resistor

D. fused jumper wire

A direct injection (DI) fuel injector system sprays high-pressure fuel, up to _______ psi, into the combustion chamber as the piston approaches the top of the compression stroke.

A. 2,900

B. 80

C. 1,000

D. 65

The voltage value at which a Zirconia oxygen sensor switches from rich to lean or from lean to rich is

A. 0.25 V (250 mV).

B. 0.5 V (500 mV).

C. 0.9 V (900 mV).

D. 0.45 V (450 mV).

After removing the vacuum hose from the fuel-pressure regulator, you see gasoline has dripped out of the hose. Technician A says that the fuel pressure regulator is defective. Technician B says that one or more of the injectors may be defective, causing the fuel to get into the hose. Who is correct?

The speed-density fuel-injection system uses the _______ sensor as the primary sensor to determine base pulse width.

A. MAF (mass air flow)

B. BARO (barometric)

C. MAP (manifold absolute pressure)

D. TP (throttle position)

The opening of the throttle plate can be delayed as long as _______ milliseconds to allow time for the amount of fuel needed to catch up to the opening of the throttle plate.

A. 90

B. 30

C. 180

D. 60

Two technicians are discussing engine coolant temperature (ECT) sensor diagnosis. Technician A says that the correct function of an ECT sensor depends on having a properly filled cooling system. Technician B says that the voltage measured on the ECT signal wire should be low when the engine is cold and high when the engine is hot. Who is correct?

Normal throttle position voltage on most vehicles is about 0.5 volt at idle (closed throttle) and about _______ volts at wide-open throttle (WOT).

A. 1.5 to 2.8

B. 4.5

C. 2.5

D. 13.5 to 15.0

Technician A says that many port fuel-injection systems on four-cylinder engines use a simultaneous firing of injectors. Technician B says that sequential fuel injectors are timed and pulsed individually, much like the spark plugs are sequentially operated in firing order of the engine. Who is correct?

Fuel lines supply fuel to the throttle body or fuel rail and return excess fuel and vapors to the tank. Which of the following best describes fuel and vapor lines?

The fuel pump in the fuel tank supplies fuel to the _______-driven high-pressure fuel pump at a pressure of approximately _______ psi.

A. AC motor, 60

B. crankshaft, 100

C. DC motor, 100

D. camshaft, 60

Two technicians are discussing how to check fuel injector resistance. Technician A says that you would use a digital ohmmeter read in tenths of an ohm to measure the resistance across the injector terminals. Technician B says that the resistance of the injectors should be measured twice—once when the engine and injectors are cold and once after the engine has reached normal operating temperature. Who is correct?

Which of these input sensors is used to calculate the amount of air volume delivered to the engine?

A. TP (throttle position)

B. MAF (mass air flow)

C. MAP (manifold absolute pressure)

D. AIT (air intake temperature)

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