Chapter 73: Emissions Control Systems
During the reinstallation of the PCV valve, the ___ should be removed from the air cleaner assembly.
Breather Tube
Inside a three-way catalytic converter, what is incoming NOx converted to as it passes through the reduction catalyst?
Nitrogen and Oxygen
Pressure buildup in the crankcase of a vehicle can cause ___.
Oil seals and gaskets to leak oil
Tech A says that testing the secondary air injection system starts with checking for any related DTC's. Tech B says that all new vehicles have a secondary air injection system. Who is correct?
Tech A
Tech A says that the MIL light is the first indication of trouble on an emissions control system. Tech B says that all states require yearly inspections of all the emissions control devices. Who is correct?
Tech A
Tech A says that the secondary air injection pump may be either electrically or belt driven. Tech B says that the secondary air injection pump is only used when the engine is fully warmed up to help cool the catalytic converter. Who is correct?
Tech A
Tech A says that to diagnose abnormal exhaust color, it is important to understand what each color represents. Tech B says that the color of exhaust cannot help diagnose abnormal exhaust. Who is correct?
Tech A
The first step in controlling engine emissions is to design the engine in such a way as to reduce emissions as much as possible, such as building ___-enhancing strategies and precisely controlling valve and spark timing.
Turbulence
The most common PCV system problem is a ___ leak.
Vacuum
If the PCV valve is located in the ___, the PCV valve should be removed and ensured that a strong vacuum is coming through the valve with the engine running.
Valve Cover
identify the reason a catalytic converter can fail when a catalyst becomes coated by a substance such as lead from leaded fuel.
Contamination
If a vehicle passes a(n) ___ test with clean results, that is a good indication that all of the engine systems and the engine itself are operating well.
Emissions
Low tail pipe ___ mean a vehicle is running efficiently, which helps to conserve energy.
Emissions
Carbon monoxide is a colorless, odorless, tasteless, ___, and highly toxic gas.
Flammable
There are two primary pre-combustion emission control systems; the ___ system and the ___ system.
Heated air intake; Exhaust Gas Recirculation
In case of a leak in the EVAP system, ___ can be released into the atmosphere.
Hydrocarbons
___ is/are 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 tailpipe.
Hydrocarbons
If the EGR valve of a vehicle is stuck in an open position, the engine will ___.
Idle Excessively Roughly
If engine operating conditions are likely to produce oxides of nitrogen, the EGR valve opens, letting some burned exhaust gases pass from the exhaust into the ___ system.
Intake
In a typical fixed-orifice PCV system, what pulls the vapors from the crankcase?
Intake manifold Vacuum
Which of the following is a function of the positive crankcase ventilation (PCV) system?
It directs blowby gases and vapors back into the intake manifold.
If nitrogen reacts under the high temperature and pressure of internal combustion, it can become:
NOx
Emissions from combustion are being discussed. Technician A states that all of the byproducts of combustion are harmful. Technician B states that of all the gases in the atmosphere, the most common is oxygen. Who is correct?
Neither
Identify a drivability concern typically caused by EGR valves.
Rough Idle Concern
The ___ effect occurs when the exhaust gases moving out of the combustion chamber create a low-pressure area in the exhaust manifold, helping to pull air and fuel into the cylinder.
Scavenging
First aid for victims of carbon monoxide poisoning starts with recognizing the signs of exposure: ___, nausea, headache, dizziness, or light-headedness.
Shortness of Breath
In vehicles with cracks and leaks that result in an EVAP system failure, the use of a(n) ___ may be necessary to find the leaks in the system.
Smoke Machine
There are two common types of electric EGR valves: the pulse-width-modulated solenoid type and the ___ motor EGR valve type.
Stepper
Which of the following is NOT a measured gas when using a five gas analyzer?
Sulfur Dioxide
An evaporative emissions (EVAP) system is being discussed. Technician A states that the EVAP system protects the environment against evaporating hydrocarbons. Technician B states that the fuel caps used in today's vehicles are vented, which allows air to flow in and out of the gas tank freely. Who is correct?
Tech A
Tech A says that if the EVAP system continues to purge at idle, a rough idle could be created. Tech B says that even a small fault in the EVAP system creates drivability issues. Who is correct?
Tech A
Tech A says that overheated catalysts cannot be restored and must be replaced. Tech B says that overheated catalysts can be easily restored by driving the vehicle for an extended time under a moderate load. Who is correct?
Tech A
Tech A says that pinging can be referred to as the sound of marbles being shaken in a glass jar. Tech B states that pinging can be referred to as the sound of water gushing in a water pipe. Who is correct?
Tech A
A blue colored exhaust typically means that ___.
The engine is burning oil
If crankcase pressure issue is not resolved, it may cause___.
The gasket to pop out of place
A stoichiometric air-fuel ratio of 14.7:1 is equal to:
1.0 Lambda
What percentage of oxygen is in the atmosphere?
20.95%
A white colored exhaust can be caused due to a(n) ___.
A blown Head Gasket
All of the following conditions lead to a black colored exhaust EXCEPT:
A blown head gasket
___ charcoal means the charcoal is porous and has a large surface area that can absorb large quantities of fuel vapor.
Activated
The ___ of a secondary air injection system pumps air into the exhaust stream and assist the operation of catalytic converter.
Air Pump
Tech A says that catalytic converters are a post-combustion control device that perform a final cleanup of tailpipe emissions. Tech B says that catalytic converters create heat as they burn off harmful gases before leaving the exhaust system. Who is correct?
Both
Tech A says that gas analyzer needs to warm up for at least 10 minutes. Tech B says that gas analyzer must be zeroed before installing the probe in a vehicle's exhaust. Who is correct?
Both
The EGR valve does not operate at idle because there is only a small amount of air-fuel mixture being burned, so the combustion temperature is ___ 2,500 F
Below
A positive crankcase ventilation (PCV) system is being discussed. Technician A states that PCV hoses should be visually inspected for softening, brittleness, cracks, kinks, and holes. Technician B states that a symptom of a clogged PCV valve could be various leaking engine oil seals and gaskets. Who is correct?
Both
A positive crankcase ventilation (PCV) system is being discussed. Technician A states that some PCV systems contain an oil separator with an oil drain pipe leading back to the crankcase. Technician B states that current PCV systems draw fresh air from the air cleaner or intake duct. Who is correct?
Both
A vehicle with an EVAP-related concern is diagnosed. Tech A says that a scan tool can be used to pull any diagnostic codes. Tech B says that if there are no diagnostic codes, the scan tool can be used to view the live sensor and actuator data .Who is correct?
Both
An evaporative emissions (EVAP) system monitor is being discussed. Technician A states that some EVAP monitoring systems use a fuel tank pressure sensor. Technician B states that the powertrain control module (PCM) commands the vent valve closed during the monitor test. Who is correct?
Both
Controlling emissions is being discussed. Technician A states that one way to control emissions is to design an engine in such a way that emissions are reduced as much as possible. Technician B states that engines should warm up as quickly as possible to lower emissions. Who is correct?
Both
Tech A says that any vehicle produced after 1996 must monitor the efficiency of the catalytic converter. Tech B says that catalyst monitoring is accomplished with multiple oxygen sensors. Who is correct?
Both
Tech A says that black exhaust indicates a very rich-running engine. Tech B says that white exhaust can indicate coolant in the exhaust. Who is correct?
Both
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?
Both
Tech A says that some manufacturers use VVT rather than EGR systems to control oxides of nitrogen. Tech B says that holding the exhaust valves open during the intake stroke will allow for some exhaust gases to be pulled into the engine, acting as an internal EGR system. Who is correct?
Both
Tech A says that some states require emissions testing with only a gas analyzer. Tech B says that some states require emissions testing with an exhaust analyzer and chassis dynamometer. Who is correct?
Both
Tech A says that the EGR valve does not function at idle. Tech B says that the EGR valve will not function during WOT. Who is correct?
Both
Tech A says that the PCV system removes blowby gases from the crankcase in a manner that is not harmful to the environment. Tech B says that the PCV system prevents the buildup of crankcase pressure. Who is correct?
Both
Tech A says that the gas cap in an EVAP system is prone to leaks. Tech B says that this can be due to the gas cap not being tightened properly. Who is correct?
Both
Tech A says that the purge valve is part of the evaporative emissions system. Tech B says that OBDII systems must illuminate the MIL when the emissions exceed 1.5 times the FTP. Who is correct?
Both
Tech A says that the two-way catalytic convertor was the first type of catalytic convertor. Tech B says that it converts hydrocarbons and carbon monoxide to carbon dioxide and water. Who is correct?
Both
Tech A states that a DTC is set if the electrical system of a secondary air injection system fails. Tech B states that a check engine light is also illuminated at that instance of component failure. Who is correct?
Both
Which exhaust gas is a result of incomplete combustion and is colorless, odorless, tasteless, flammable, and highly toxic?
CL
Particulates from modern engines are usually small particles of ___.
Carbon
How does the exhaust gas recirculation (EGR) system lower NOx emissions?
Catalytic converter is cooled which increases its chemical efficiency (B)
What is the best location for a spark plug when manufacturers are designing combustion chambers for the lowest possible emissions?
Center
In an evaporative emissions (EVAP) system, where are fuel vapors stored?
Charcoal Canister
Which of the following is NOT an example of emissions testing equipment?
DMM/Test Light
Catalytic converters come in two types: ___ and ___.
Oxidizing; Reduction
What DTC will be set by the PCM if the ECM detects a large leak in the EVAP system?
P0455
What DTC will be set by the PCM if the ECM detects a small leak in the EVAP system?
P0456
Which emissions system is designed to draw out blowby gases from the crankcase and send them back through the intake manifold?
PCV
identify the system that is used to remove blowby gases from the crankcase in an environmentally friendly manner.
PCV System
A drivability concern caused by an EGR valve is called ___ and is a pre-ignition or detonation concern.
Pinging
What will happen if blowby gases are not removed from the crankcase of a vehicle?
Pressure buildup can occur
In the combustion chamber, where surface temperatures are low, the combustion flame can be ___.
Quenched
The reduction catalyst in a catalytic converter helps to:
Reduce the oxides of nitrogen molecules into their base compounds.
When the catalyst of a catalytic converter is contaminated with lead and silicone, then the converter must be typically ___.
Replaced
Air-fuel ratio is being discussed. Technician A states that a mixture with too much air and not enough fuel is considered rich. Technician B states that engines use many sensors to detect conditions, and that information is used to adjust the fuel injector spray time. Who is correct?
Tech B
An exhaust gas recirculation (EGR) system is being discussed. Technician A states that the EGR valve is normally open on start-up and closes as the engine gets warm. Technician B states that some manufacturers have used variable valve timing (VVT) to accomplish the same reduction in NOx as an EGR system. Who is correct?
Tech B
Tech A says that air should be injected into the exhaust manifold at all times. Tech B says that air should not be injected into the exhaust manifold at all times. Who is correct?
Tech B
Tech A says that secondary air injection is only used on vehicles equipped with a three-way catalytic converter. Tech B says that secondary air injection systems may not be needed due to the efficient engine designs and reduced emissions. Who is correct?
Tech B
Tech A says that the PCV system recirculates exhaust gases into the intake manifold. Tech B says that there are three different types of PCV systems. Who is correct?
Tech B
The catalytic converter is being discussed. Technician A states that the catalytic converter is designed to clean up the emissions of a poorly running engine. Technician B states that a modern catalytic converter's operation is monitored by oxygen sensors both before and after the catalyst. Who is correct?
Tech B
The stoichiometric air-fuel ratio is being discussed. Technician A states that the stoichiometric ratio is 14.7 parts of air to 1 part of fuel by volume. Technician B states that a ratio of 15.0:1 by weight is a lean mixture. Who is correct?
Tech B
In which of these cases is the catalytic converter most likely to be saved?
When contaminated by carbon
Physical damage to a catalytic converter can occur under all of the following conditions EXCEPT:
When the catalyst is coated by silicone from improper sealants.
There is one condition when oxides of nitrogen are being created in large amounts and the RGR valve does not operate: it is___.
When the vehicle is operated in WOT
