Automotive Engine Performance Post Test Review

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

At the fuel pump sender assembly.

The MIL light of an OBD-equipped vehicle is flashing. Technician A says a spark plug wire may be shorted to ground. Technician B says a cylinder may have low compression. Who is correct?

Both A and B.

While discussing EI systems, Technician A says that crankshaft sensors sometimes need re-synchronized with the cam sensors. Technician B say that the gap on crankshaft sensors can be adjusted on some engines. Who is correct?

Both A and B.

While discussing EVAP valves, Technician A says the evaporative emissions system has to be able to detect a leak as small as 0.010" in size. Technician B says that the initial vacuum pull down test works by closing the purge and vent valves and watching to see if the tank pressure rises. Who is correct?

Both A and B.

While discussing J2534 pass-through programming: Technician A says that before programming a module, make certain that the battery voltage is at least 12.5 volts. Technician B says that after a module is programmed, there may be additional steps to set up the module, such as setting tire size. Who is correct?

Both A and B.

While discussing direct fuel injection (DFI), Technician A says some DFI systems utilize port fuel injectors in the intake to improve performance. Technician B says some DFI systems utilize port fuel injectors in the intake manifold to help keep the intake valves clean.

Both A and B.

While discussing primary and secondary ignition circuits, Technician A says that the primary circuit controls the secondary circuit. Technician B says that the primary circuit also controls ignition timing in the secondary circuit. Who is correct?

Both A and B.

While discussing the diagnosis of an coil near plug system in which the crankshaft and camshaft sensor tests are satisfactory but a spark tester connected from the spark plug wires to ground does not fire, Technician A says the coil assembly may be defective. Technician B says the voltage supply wire to the coil assembly maybe open. Who is correct?

Both A and B.

While discussing the diagnosis of an EI system, Technician A says the primary coil normally has between 5,000 and 20,000 ohms of resistance. Technician B says the coil secondary normally has less than 2 ohms of resistance. Who is correct?

Neither A or B.

Technician A says Mode 5 contains the tests for non-continuously monitored systems. Technician B says Mode 6 contains the oxygen sensor monitoring tests. Who is correct?

Neither A or B.

Technician A says fuel injectors may be cleaned by soaking them in solvent. Technician B says it is a good idea to use a wire brush to unclog injectors. Who is correct?

Neither A or B.

The acceptable amount of ethanol mixed with conventional gasoline is:

Up to 10%.

The period of time that the exhaust and intake valves are both open is called:

Valve overlap.

Oil is found in the air filter housing. Which of the following conditions could be the cause?

Worn piston rings or a clogged PCV valve.

An air filter that is contaminated with oil may be caused by:

A defective PCV system and excessive engine blowby.

Which of the following can cause a high HC reading?

A faulty spark plug wire.

While discussing how to test CKP sensors, Technician A says that a DVOM can be used on some types of sensors. Technician B says that an oscilloscope can be used on some types of sensors. Who is correct?

Both A and B.

For work to have taken place, a mass can be:

Lifted and Moved.

The "W" in engine oil represents?

Oil viscosity at 0 degrees F.

Which of these statements about modern mass air flow sensors is true?

The sensor produces a digital signal.

Magnetic pulse generators are commonly used to send data to the computer about:

The speed of the monitored component.

As engine load rises what happens to manifold pressure?

Vacuum goes down.

The purpose of the PCV system is to:

Control emissions, relieve the engine's crankcase of pressure and vapors, and reduce the formation of oil sludge.

An intercooler is used to:

Cool the air from a supercharger or turbocharger before it reaches the combustion chamber.

To help isolate a clogged or dirty injector:

Perform an injector balance test.

Excessive CO emissions may be caused by:

Rich air-fuel mixtures.

Technician A says in a COP system the PCM can control timing on a cylinder by cylinder basis. Technician B says COP allows less time for coil saturation. Who is correct?

Technician A only.

Technician A says that actuators perform the actual work commanded by the PCM. Technician B says that actuators have to be relays. Who is correct?

Technician A only.

Technician A says that cylinders having excessive blow by may cause oil to be present in the air cleaner. Technician B says a PCV valve recirculates crankcase vapors into the exhaust system. Who is correct?

Technician A only.

Technician A says that the permanent magnet sensor is basically a magnet and a coil of wire. Technician B says that permanent magnets sensors produce a DC voltage signal. Who is correct?

Technician A only.

Technician A says a fuel level sensor malfunction may cause a trouble code to set. Technician B says the evaporative emissions check test is only run when the fuel tank is empty. Who is correct?

Technician A.

Technician A says a type A misfire will set a trouble code on the first failure. Technician B says a type B misfire will set a trouble code on the first failure. Who is correct?

Technician A.

Technician A says an EGR valve recirculates exhaust back into the air intake stream. Technician B says an EGR valve increases combustion chamber temperatures. Who is correct?

Technician A.

The best way to check for cylinder contribution is:

A power balance test.

Technician A says an OBD II drive cycle is easily completed every time the vehicle is driven. Technician B says enabling criteria defines the criteria that must be met in order for a monitor test to be completed. Who is correct?

Technician B.

Technician A says both the fuel injector and spark plug are turned off when a cylinder is deactivated on a variable displacement engine. Technician B says the spark plug may foul if is allowed to become too cool during cylinder deactivation. Who is correct?

Technician B.

The supercharger is driven by:

The crankshaft.

A cylinder leakage test is used to determine which of the following:

The source of leakage from a cylinder and to measure the percentage of compression lost.

The component that permits fast warmup of the engine after it has been started is the:

Thermostat.

Which of the following is false concerning variable valve timing engines?

They utilize the camshaft (CMP) and crankshaft (CKP) sensors to determine the amount of advance or retard.

True or False: Long term fuel trim will change in an attempt to keep short term fuel trim near 0.

True

True or False: A disconnected vacuum hose on a fuel pressure regulator may cause excessive fuel pressure.

True.

True or False: Engine pressure sensors read any pressure above a perfect vacuum.

True.

True or False: The manifold absolute pressure (MAP) sensor monitors engine load.

True.

True or False: Waste spark systems deliver spark to two cylinders (companion) at once.

True.

A waste spark ignition system equipped vehicle has a no-spark condition. Technician A says the crankshaft position sensor may be defective. Technician B says the ignition module may be defective. Who is correct?

Both A and B.

Technician A says that poor grounds can be identified by conducting voltage drop tests and monitoring the circuit with a lab scope. Technician B says that when conducting a voltage drop test the circuit must be turned on and have current flowing through it. Who is correct?

Both A and B.

Technician A says the air intake temperature sensor (IAT) signal is very similar to the engine coolant temperature sensor signal. Technician B says the IAT can affect ignition timing. Who is correct?

Both A and B.

Technician A says the comprehensive component monitor is used to check devices that do not have their own monitor. Technician B says the comprehensive component monitor also checks the wiring for shorts and opens. Who is correct?

Both A and B.

A perfect vacuum is said to have been reached at:

14.7 in Hg.

Variable cam timing is used to allow high overlap at:

High RPM.

A three-way catalyst is named for its ability to reduce which emissions:

NOx, CO, HC.

A low voltage signal from the O2 sensor indicates:

A lean air-fuel ratio.

Excessive HC emissions may be caused by all of these, except:

An EGR valve stuck open.

A waste spark ignition system fires on which two strokes?

Compression and exhaust.

Which of the following is a pre-combustion emission control?

EVAP

The OBD II AIR system pumps air into the:

Exhaust manifold.

True or False: During cruising and idle operation, Direct gasoline injection (GDI) systems spray fuel directly into the combustion chamber when the intake valve is opened.

False.

True or False: Feedback circuits only refer to O2 sensor information.

False.

True or False: On most electronic ignition systems base timing needs to checked and adjusted whenever the system is serviced.

False.

True or False: Open loop is utilized as much as possible on an OBD2 application.

False.

True or False: Semi return less fuel systems vary fuel pressure to ensure correct atomization.

False.

True or False: Surging at low speeds or a rough idle may occur if the EGR valve is stuck closed.

False.

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

False.

The OBD II EVAP system is designed to reduce which emission?

HC.

A defective engine coolant temperature may cause:

Hard engine starting, reduced fuel economy, and a rich air/fuel ratio.

A pending code is one that:

Has had one failure but has not had a second consecutive failure.

All of the following situations may call for timing advance except:

Heavy engine load (high pressure).

The measurement of the rate at which work is performed is measured in:

Horsepower.

OEM active intake manifolds are designed to do what?

Increase air velocity for low RPM performance.

If the pressure is increased on a gas in an enclosed container, the temperature of the gas will:

Increase.

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

Increases fuel pressure.

In order for the PCM to achieve closed loop operation all criteria must be met except:

Intake air temperature must be at least 32 degrees F.

The computer may use the manifold absolute pressure sensor to monitor all of the following except:

Intake manifold air flow

A turbocharger may be damaged by:

Lack of oil, contaminants in the oil, and ingestion of foreign material through the air intake.

Which of the following OBD-II test modes allows scan tools to access freeze frame data?

Mode 2.

An O2 sensor may be used to:

Monitor the air/fuel ratio and monitor the condition of the catalytic converter.

Which exhaust gas /gasses are controlled by the EGR valve?

NOx.

The output voltage of a downstream O2 sensor is fluctuating when the engine is at operating temperature. Technician A says the catalytic converter is working efficiently. Technician B says the O2 sensor may need to be replaced. Who is correct?

Neither A and B.

Short-term fuel trim (STFT) adds or subtracts fuel to correct for:

Small or temporary changes and changes in the O2 sensor signal.

Which of the following can be used to locate both exhaust and vacuum leaks?

Smoke.

The result of a plugged catalytic converter can cause an exhaust restriction which in turn will cause:

Stalling, popping, backfire, and/or a loss of power.

Excessive oxygen in the exhaust gas stream will cause a zirconia oxygen sensor to:

Stay below 450mv.

Engine displacement is calculated by using which of the following:

Stroke, bore, and number of cylinders.

The signal that alerts the misfire monitor that a misfire may be occurring is provided by the:

The crankshaft position sensor.

The ignition switch, primary coil winding, and module are all components of:

The primary ignition circuit.

True or False: Inertia switches open the fuel pump circuit in case of a severe impact.

True.

True or False: The ignition coil is both a primary and secondary ignition component.

True.

True or False: The octane number indicates the antiknock quality of gasoline.

True.

True or False: To relieve fuel system pressure, the fuel pump circuit should be disconnected and the engine should be started and ran until it shuts off.

True.

Exhaust passes by which wheel of a turbocharger?

Turbine wheel

A Hall-effect switch is being analyzed on a lab scope. The high part of the signal measures 5.0 volts. Ideally, what should the low part of the signal read?

0.0 volts.

At 2,000 rpm, the maximum allowable exhaust back pressure is approximately:

1.2 psi.

Oxides of nitrogen (NOx) are formed when combustion temperatures reach more than:

2,500 degrees F.

A V6 engine requires how many spark events (spark plug firings) per crankshaft revolution?

3.

Twenty inches of vacuum would be equivalent to how much pressure absolute?

5 psia.

An oscilloscope test shows firing lines the same, but abnormally high. This is the result of:

A lean air-fuel mixture.

A flashing MIL indicates:

A misfire that may damage the catalytic converter.

A partially restricted or blocked exhaust system may result in:

A rough idle and loss of engine power.

The type of oxygen sensor that changes current flow to indicate exhaust oxygen content is the:

Air-fuel ratio sensor.

Technician A says a P0300 is considered a generic DTC. Technician B says a P1300 is considered a manufacturer specific DTC.

Both A and B

Technician A says a quad driver has four independently controllable outputs. Technician B says some output driver modules may control up seven independent outputs. Who is correct?

Both A and B

Technician A says pulse width modulation (PWM) is measured in a length of time, not a percentage of a cycle. Technician B says that the cooling fan relay is usually controlled by the PCM through PWM. Who is correct?

Both A and B

Technician A says vapor lock can be caused by excessive under hood temperatures. Technician B says vapor lock can be caused by low fuel pressure. Who is correct?

Both A and B.

Technician A say canister purging occurs only when conditions are correct. technician B says modern purge valves are computer controlled. Who is correct?

Both A and B.

Technician A say that maximum cylinder pressure occurs around 10-20 degrees ATDC. Technician B say that timing is manipulated to have the combustion event occur prior to maximum cylinder pressure. Who is correct?

Both A and B.

Technician A says a P0300 is considered a generic DTC. Technician B says a P1300 is considered a manufacturer specific DTC. Who is correct?

Both A and B.

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?

Both A and B.

Technician A says a quad driver has four independently controllable outputs. Technician B says some output driver modules may control up seven independent outputs. Who is correct?

Both A and B.

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?

Both A and B.

Technician A says analog MAF sensors should produce a relatively smooth signal at idle. Technician B says MAF sensors can incorporate a IAT sensor.

Both A and B.

Technician A says any induction air leak after the MAF sensor can cause a poor running condition. Technician B says an air leak after the MAF sensor results in un-metered air. Who is correct?

Both A and B.

Technician A says if a timing belt or chain becomes excessively worn, it is possible that a change in valve timing accuracy will result. Technician B says an excessively worn timing chain or belt can cause the timing to jump. Who is correct?

Both A and B.

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?

Both A and B.

Technician A says if the firing voltage is higher than normal the burn time will decrease. Technician B says if the firing voltage is lower than normal the burn time will increase. Who is correct?

Both A and B.

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

Both A and B.

Technician A says most replacement network modules have to be reprogrammed. Technician B says that some replacement modules can be customized by programming certain features for a customer. Who is correct?

Both A and B.

Technician A says non-contact TPS sensors can redundantly monitor the same sensor to ensure accuracy. Technician B says non-contact sensors are so good only one may be needed.

Both A and B.

Technician A says placing the turbocharger close to the exhaust helps its efficiency. Technician B says the turbocharger shaft may turn at speeds in excess of 100,000 rpm. Who is correct?

Both A and B.

Technician A says that a duty cycle is a percentage of time in a fixed cycle that a device is on. Technician B says that if a full cycle were 1 second in length, a 50% duty cycle means that the device was on for .5 seconds. Who is correct?

Both A and B.

Technician A says that compression can be raised by physically modifying the engine. Technician B says that compression can be effectively raised by using a turbocharger to force air into the engine. Who is correct?

Both A and B.

Technician A says that ion-sensing ignition systems are based on the coil on plug system. Technician B say that the ion-sensing ignition system uses the spark plug itself as a sensor. Who is correct?

Both A and B.

Technician A says that when a ground controlled (low-side) driver is turned off, the voltage trace on the oscilloscope at the actuator goes high. Technician B says that when a driver controlled (high-side)actuator is turned off, the oscilloscope trace at the actuator goes low. Who is correct?

Both A and B.

Technician A says the computer may activate a circuit by completing the path to ground. Technician B says the computer may activate a circuit by completing the path to power. Who is correct?

Both A and B.

Technician A says the crankshaft position sensor can be a Hall-effect switch. Technician B says the crankshaft position sensor can be a magnetic pulse generator. Who is correct?

Both A and B.

Which exhaust gas is near its highest level when the air/fuel ratio is near stoichiometric?

CO2

All of the following are OBD II continuous monitors, except:

Catalyst Efficiency.

Which of the following is not part of comprehensive component monitoring?

Catalyst Efficiency.

Intake manifold vacuum is highest during what operating condition?

Deceleration.

The vent valve in an evaporative emissions system may be:

Opened to allow fresh air through the charcoal canister and closed with the purge valve open while the PCM monitors the fuel tank pressure sensor for vacuum.

All CAN protocol messages contain all of the following information except:

Other modules acknowledge the message.

All of the following are examples of advantages of EI except:

Reduced spark burn time.

Magnetic pulse generators can be checked by which of the following:

Resistance test, AC voltage test, and waveform signature test.

Technician A says that some spark testers look like a spark plug, but they have a very large electrode gap. Technician B says that when the engine is cranked to check for voltage output, the ignition coil is forced to produce a lower voltage to overcome the reduced resistance created by the wide gap. Who is correct?

Technician A only.

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?

Technician A.

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?

Technician A.

Technician A says fuel pumps can be checked for amperage draw and current waveform. Technician B says a low amp probe is connected in series with the circuit being tested. Who is correct?

Technician A.

Technician A says low compression pressures could prevent combustion from occurring inside a cylinder. Technician B says compression pressure is not a factor for complete combustion. Who is correct?

Technician A.

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?

Technician A.

While discussing direct fuel injection (DFI), Technician A says the DFI injector may require a special tool to remove it from the cylinder head. Technician B says the DFI high-pressure fuel line from the high-pressure pump to the fuel rail can be reused only twice before replacement. Who is correct?

Technician A.

Technician A states the purpose of an ignition control module is to ground the secondary circuit. Technician B states the purpose of an ignition control module is to ground the primary circuit. Who is correct?

Technician B only

Technician A says that a crankshafts sensors primary responsibility is fuel synchronization. Technician B says that hall-effect sensors are used as crankshaft and or camshaft sensors. Who is correct?

Technician B only.

Technician A says that serial data is what the scan tool uses to communicate with the PCM and modules. Technician B says that bi-directional control can be used to diagnose outputs. Who is correct?

Technician B only.

Technician A states that non-contact type hall-effect sensors wear out very quickly. Technician B states that some throttle position sensors are non-contact.

Technician B only.

Technician a says that the communication protocol called UART has been around since the early 1980's. Technician B says that CAN was the standard for all emission-related modules starting in 2008. Who is correct?

Technician B only.

While testing ignition coils in an EI system, Technician A says that an infinity reading means that the windings have zero resistance and are shorted. Technician B say that the primary windings in some EI coils cannot be measured with an ohmmeter. Who is correct?

Technician B only.

Spark plugs are being discussed: Technician A says iridium spark plugs should not have the gap checked by the technician. Technician B says platinum spark plugs should not have the electrode filed. Who is correct?

Technician B.

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?

Technician B.

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 underhood fuel system components into the fuel pump and tank. Who is correct?

Technician B.

Technician A says the PCM supplies power and ground to magnetic pulse generators. Technician B says the PCM supplies power and ground to Hall-effect sensors. Who is correct?

Technician B.

Technician A says the ignition timing must retard as RPM increases. Technician B says ignition timing is retarded under maximum load. Who is correct?

Technician B.

True or False: If dwell time is to short, the coil and module can overheat.

True

True or False: A defective crankshaft position sensor is a common cause of a no-start condition.

True.

True or False: A negative fuel trim indicates the engine is running rich.

True.

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

True.

True or False: Faulty PCV valves can cause premature engine failure.

True.

The principle that describes using a restriction to increase the speed of a liquid or a gas is called:

Venturi principle.