Comprehensive Engine Performance Assessement

1. True or False. The illuminated malfunction indicator lamp (MIL) lets the tech know that there is an emission problem that needs to be diagnosed.

True

False

The check engine light or malfunction indicator lamp are responsible of notifying the driver of a concern with emission regulation equipment.

Explanation

The check engine light or malfunction indicator lamp are responsible of notifying the driver of a concern with emission regulation equipment.

2. Emissions can be caused naturally by:

Forest fires.

Volcanoes.

Decomposition of materials.

All of the above

Emissions are a product of combustion. Combustion is naturally occurring and so are instances that aren't man made.

Explanation

Emissions are a product of combustion. Combustion is naturally occurring and so are instances that aren't man made.

3. A limit value is the maximum amount of _____________ that a vehicle is permitted to emit.

Speed

Emissions

Air

Water

There is a limit on how much of each harmful gas a vehicle can emit.

Explanation

There is a limit on how much of each harmful gas a vehicle can emit.

4. What does the Environmental Protection Agency (EPA) require all vehicles to have to warn the driver of an emission fault?

A beeping horn

An illuminated light

A buzzing buzzer

A ringing bell

A light MUST BE in every vehicle that has OBD II.

Explanation

A light MUST BE in every vehicle that has OBD II.

5. Tech A says that carbon monoxide is lethal. Tech B says never run an engine inside a closed shop without proper exhaust ventilation. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

CO will kill you. An engine running in an unventelated shop will harbor this deadly gas.

Explanation

CO will kill you. An engine running in an unventelated shop will harbor this deadly gas.

6. Today's emissions come from the vehicle's:

Fuel system.

Crankcase.

Tailpipe.

All of the above

Unwanted vehicle emissions are created from all of the above.

Explanation

Unwanted vehicle emissions are created from all of the above.

7. ______________ is a colorless, odorless, tasteless, flammable, and highly toxic gas.

Carbon dioxide

Hydrocarbons

Carbon monoxide

Sulfur

CO is a harmful gas to humans. It will suffocate you.

Explanation

CO is a harmful gas to humans. It will suffocate you.

8. In automotive applications, most_______________ is/are a by-product of combustion and is/are emitted from the exhaust system.

Fuel

Air

Emissions

Catalysts

Most emissions created from cars is from the tailpipe.

Explanation

Most emissions created from cars is from the tailpipe.

9. The stoichiometric ratio, also referred to as lambda, is the ratio of air to fuel at which all of the oxygen in the air and all the fuel are completely burned. The stoichiometric ratio for gasoline is:

34.3:1.

17.2:1.

15.7:1.

14.7:1.

14.7:1 is the sweet spot for engine performance and emissions.

Explanation

14.7:1 is the sweet spot for engine performance and emissions.

10. True or False. The main concern of the evaporative emission (EVAP) system is the gas cap.

True

False

Yes, the fuel filler cap is by far the most over looked component of the EVAP emissions system, by both customers and technicians.

Explanation

Yes, the fuel filler cap is by far the most over looked component of the EVAP emissions system, by both customers and technicians.

11. Which of the following methods may be used to manually perform a cylinder power balance test?

Unplug the ignition from each cylinder.

Unplug the fuel injectors.

Both A and B

None of the above

To perform a power balance test, either the ignition or the fuel can be disabled.

Explanation

To perform a power balance test, either the ignition or the fuel can be disabled.

12. The purpose of the vehicle speed sensor (VSS) is to measure the:

Turbulence in the incoming airstream.

Throttle position.

Speed of the vehicle.

Coolant temperature.

VSS is an acronym for vehicle speed sensor.

Explanation

VSS is an acronym for vehicle speed sensor.

13. ____________ is a by-product of complete combustion, along with water.

Carbon monoxide

Hydrocarbons

Carbon dioxide

Sulfur

CO2 is a by-product of complete combustion.

Explanation

CO2 is a by-product of complete combustion.

14. Tech A says that closed loop is when the feedback system is ignoring the sensors. Tech B says that closed loop is when the feedback system uses all the sensors to control the PCM. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Closed loop is when there is an intact feedback system and the PCM uses its inputs to make engine running adjustments.

Explanation

Closed loop is when there is an intact feedback system and the PCM uses its inputs to make engine running adjustments.

15. ____________ is created when raw fuel evaporates into the atmosphere or when it does not burn at all in the combustion chamber and is exhausted out the tail pipe.

Carbon dioxide

Hydrocarbons

Carbon monoxide

Sulfur

Raw fuel is primary comprised of hydrogen and carbon.

Explanation

Raw fuel is primary comprised of hydrogen and carbon.

16. True or False. The evaporative emission (EVAP) system is designed to ensure that hydrocarbons are released into the atmosphere.

True

False

The EVAP emissions system's sole purpose is to harness evaporated HC and to direct it into the engine intake to be burned.

Explanation

The EVAP emissions system's sole purpose is to harness evaporated HC and to direct it into the engine intake to be burned.

17. In what year did it become mandatory for all vehicles to be on-board diagnostic II (OBDII) compliant?

1994

1995

1996

1997

Federally mandated OBD II was put into effect in 1996. It was a landmark year for the automotive industry.

Explanation

Federally mandated OBD II was put into effect in 1996. It was a landmark year for the automotive industry.

18. The collapse of the magnetic field inside the ignition coil happens as a result of the interruption of current to the:

Primary winding.

Secondary winding.

Ignition control module.

Electronic control module (ECM).

The collapse of voltage occurs on the primary side of the ignition coil.

Explanation

The collapse of voltage occurs on the primary side of the ignition coil.

19. The term _________________, when used in automotive circles, normally refers the pollution produced by a light vehicle during operation of the vehicle or while sitting stationary.

Catalyst

Compression

Combustion

Emission

Emissions are the polluting discharge of a running vehicle.

Explanation

Emissions are the polluting discharge of a running vehicle.

20. A variation in pulse width at a fixed frequency is called:

Duty cycle.

Analog cycle.

Pulse-width modulation.

Digital cycle.

The control for the duty cycle is called a pulse width modulation.

Explanation

The control for the duty cycle is called a pulse width modulation.

21. Tech A says that under high temperature and pressure of combustion, oxides of nitrogen is produced. Tech B says that oxides of nitrogen are only produced at temperatures less than 500°F. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

NOx is a by-product of incomplete combustion and will result in higher exhaust temperatures. NOx are created at all temperatures, but lots of them are created when there is extreme heat.

Explanation

NOx is a by-product of incomplete combustion and will result in higher exhaust temperatures. NOx are created at all temperatures, but lots of them are created when there is extreme heat.

22. Tech A says that the positive crankcase ventilation (PCV) system removes blow-by gases from the crankcase in a manner that is not harmful to the environment. Tech B says that the PCV system prevents the build-up of crankcase pressure. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

The PCV system's responsibility is to recycle blow by gasses back into the engine to be burned. It also relives the build up of pressure created by these blow by gasses.

Explanation

The PCV system's responsibility is to recycle blow by gasses back into the engine to be burned. It also relives the build up of pressure created by these blow by gasses.

23. Tech A says that a slightly lean mixture offers good fuel economy and low exhaust emissions. Tech B says that a mixture that is too rich fouls spark plugs and causes incomplete burning. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Both Tech A and Tech B are correct. A slightly lean mixture, meaning there is more air than fuel, can offer good fuel economy and low exhaust emissions. On the other hand, a mixture that is too rich, meaning there is more fuel than air, can foul spark plugs and cause incomplete burning. Therefore, both statements are accurate and provide valid explanations for the effects of different fuel mixtures.

Explanation

Both Tech A and Tech B are correct. A slightly lean mixture, meaning there is more air than fuel, can offer good fuel economy and low exhaust emissions. On the other hand, a mixture that is too rich, meaning there is more fuel than air, can foul spark plugs and cause incomplete burning. Therefore, both statements are accurate and provide valid explanations for the effects of different fuel mixtures.

24. In what year was the positive crankcase ventilation (PCV) first used on vehicles' emission systems?

1959

1960

1961

1962

Another landmark year in automotive mechanics. 1961 is the year for the introduction of the PCV system.

Explanation

Another landmark year in automotive mechanics. 1961 is the year for the introduction of the PCV system.

25. When performing a cylinder leakage test, a small amount of air leakage can be heard from the exhaust tail pipe. This indicates:

Worn valve guides.

A bent intake valve.

A leaking cylinder head gasket.

A bad exhaust valve

A leak heard from the associated part of the compression chamber will lead you to the bad sealing component.

Explanation

A leak heard from the associated part of the compression chamber will lead you to the bad sealing component.

26. When testing intake manifold vacuum, the gauge needle oscillates back and forth rapidly, which generally indicates:

A partially restricted exhaust

A mechanical condition such as a burned or bent valve.

Late ignition or valve timing.

None of the above

The needle oscillations are an indication of an internal mechanical fault, which occurs as rapidly as the engine turns.

Explanation

The needle oscillations are an indication of an internal mechanical fault, which occurs as rapidly as the engine turns.

27. The on and off time of a stepper motor relates to its duty cycle, which is generally expressed as a:

Percentage.

Numeric value.

Binary number.

Hexi-decimal value.

The amount of time something is on or off, the duty cycle, is expressed as a percentage.

Explanation

The amount of time something is on or off, the duty cycle, is expressed as a percentage.

28. The type of ignition system in which two cylinders share one coils is called a:

Distributor ignition system.

Waste spark ignition system.

Coil-on plug ignition system.

None of the above

It's called waste spark because it fires on a pair of engine cylinders on opposite engine cycles.

Explanation

It's called waste spark because it fires on a pair of engine cylinders on opposite engine cycles.

29. Tech A says that ignition coils are essentially transformers. Tech B says that the primary side of the coil delivers the high voltage spark that is necessary to jump the plug gap. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Ignition coils transform low voltage into high voltage to jump the gap of the spark plug. The secondary side delivers the high voltage to jump this gap.

Explanation

Ignition coils transform low voltage into high voltage to jump the gap of the spark plug. The secondary side delivers the high voltage to jump this gap.

30. Tech A says that hydrocarbons are created when raw fuel does not burn completely in the combustion chamber and is exhausted out the tailpipe. Tech B says that hydrocarbons are created when raw fuel evaporates into the atmosphere. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Raw fuel is primarily comprised of hydrogen and carbon, whether liquid or vapor.

Explanation

Raw fuel is primarily comprised of hydrogen and carbon, whether liquid or vapor.

31. A high-voltage spark must cross the spark plug electrode as the piston approaches top dead center (TDC) of the

Exhaust stroke.

Ignition stroke.

Intake stroke.

Compression stroke.

Once the fuel and air mixture has compressed, a spark is needed to ignite the mixture.

Explanation

Once the fuel and air mixture has compressed, a spark is needed to ignite the mixture.

32. Tech A says that engine misfiring will cause a lean exhaust condition. Tech B says that engine misfiring can cause overheating of the catalytic converter. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

When an cylinder misfires, the fuel remains unburned. The catalyst speeds the reaction of converting unwanted combustion by-products into safer emissions. This process is exothermic and is exaggerated when there is an excess of hydrocarbons in the exhaust.

Explanation

When an cylinder misfires, the fuel remains unburned. The catalyst speeds the reaction of converting unwanted combustion by-products into safer emissions. This process is exothermic and is exaggerated when there is an excess of hydrocarbons in the exhaust.

33. Today's vehicle technology has reduced the harmful emissions on new vehicles to almost:

0%.

5%.

10%.

15%.

With all of the progressive technology available today, emissions of vehicles is approaching zero.

Explanation

With all of the progressive technology available today, emissions of vehicles is approaching zero.

34. Tech A says that fuel pump pressure can often be tested by accessing a test port. Tech B says that fuel pump volume can be affected by the condition of the fuel injectors. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

If there is a test port to test supply pressure, that's the way to go.
The fuel pump determines the amount of fuel delivered. The injectors only open and close.

Explanation

If there is a test port to test supply pressure, that's the way to go.
The fuel pump determines the amount of fuel delivered. The injectors only open and close.

35. Tech A says that the crankshaft sensor is used to determine vehicle speed. Tech B says the cam sensor is used to control fuel pump speed. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

The vehicle speed sensor (VSS) is responsible for inputting vehicle speed.
The cam sensor is responsible for inputting camshaft position to the ECM.

Explanation

The vehicle speed sensor (VSS) is responsible for inputting vehicle speed.
The cam sensor is responsible for inputting camshaft position to the ECM.

36. In what year did the catalytic convertor first make its appearance on automobiles' emission control systems?

1970

1971

1972

1973

1973 is the year when the catalytic converter premiered.

Explanation

1973 is the year when the catalytic converter premiered.

37. Tech A says that the exhaust gas recirculation (EGR) valve does not function at idle. Tech B says that the EGR valve will not function during wide-open throttle (WOT). Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

The EGR valve mostly operates during cruising speeds. At idle, the engine will run very poorly. The need for performance supersedes the need for EGR system operation.

Explanation

The EGR valve mostly operates during cruising speeds. At idle, the engine will run very poorly. The need for performance supersedes the need for EGR system operation.

38. Tech A says that the more oxygen the engine uses means the engine is running a rich mixture. Tech B says that the less oxygen the engine uses means the engine is running a lean mixture. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Tech A's statement is incorrect because a rich mixture means there is more fuel relative to the amount of oxygen, not necessarily more oxygen usage. Tech B's statement is also incorrect because a lean mixture means there is more oxygen relative to the fuel, but it does not imply that less oxygen is being used overall. In fact, a lean mixture has more oxygen available compared to fuel, contrary to Tech B's statement.

Explanation

Tech A's statement is incorrect because a rich mixture means there is more fuel relative to the amount of oxygen, not necessarily more oxygen usage. Tech B's statement is also incorrect because a lean mixture means there is more oxygen relative to the fuel, but it does not imply that less oxygen is being used overall. In fact, a lean mixture has more oxygen available compared to fuel, contrary to Tech B's statement.

39. The pattern in which a lab scope shows all the cylinders firing in sequence is called the:

Parade pattern.

Raster pattern.

Spark line.

Firing line.

On an lab scope, the spark voltages as they are read is called a parade pattern.

Explanation

On an lab scope, the spark voltages as they are read is called a parade pattern.

40. When checking cranking compression, which of the following malfunctions is either confirmed or ruled out by performing a wet test on a cylinder with low compression?

None of the above

A small hole in the top of the piston

A burned exhaust valve

A leaking cylinder head gasket

A wet compression test validates the seal provided by the piston rings.

Explanation

A wet compression test validates the seal provided by the piston rings.

41. Tech A says that during open loop operation, the engine control module (ECM) ignores the oxygen sensor signal and operates based on the last known ECM values. Tech B says that during ECM last known values, the following sensors run: manifold absolute pressure (MAP) sensor, mass airflow (MAF) sensor, throttle position sensor (TPS), and intake air temperature (IAT) sensor. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

During open loop, the ECM / PCM does ignore the O2 sensors, but it uses preprogrammed values to run the engine. The MAP is an active value. To run well, it needs current readings.

Explanation

During open loop, the ECM / PCM does ignore the O2 sensors, but it uses preprogrammed values to run the engine. The MAP is an active value. To run well, it needs current readings.