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Exam 6: Exhaust Gas Analysis

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Question 1

Multiple Choice

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When an engine has good combustion (proper compression and volumetric efficiency, proper spark timing and delivery, and a stoichiometric air-fuel ratio) , which level of gas emissions should be high?

A) CO emissions
B) CO₂ emissions
C) O₂ emissions
D) NO_X emissions

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Question 2

Multiple Choice

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An engine has excessive oxygen (O₂) readings at idle. At 2500 RPM, the readings are normal. Which condition is the most likely cause?

A) A restricted fuel filter
B) A leaking fuel injector
C) A vacuum leak
D) A cracked spark plug

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C

Question 3

Multiple Choice

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An exhaust gas analyzer (concentration sampling type) is being used to sample the exhaust of a vehicle that has an exhaust system leak.  Which of these four gasses will read higher than normal?

Which gas can be used an indicator of a lean condition?

When a concentration-type gas analyzer has been properly warmed up and its probe is exposed to ambient air, what should the displayed oxygen reading indicate?

An exhaust analyzer that measures lambda is being discussed. Technician A says a lambda reading of 0.98 to 1.02 is considered normal. Technician B says a lambda of 1.12 indicates a lean condition. Who is correct?

​ A vehicle with a return-type fuel injection system is being tested with an exhaust gas analyzer and the following results are obtained (AIR pump disabled) : At Idle:                                                                        At2500 RPM: CO₂   =    8.10 %                                                     CO₂     =    9.70 % CO    =    10.00 % (pegged high)                           CO      =    8.13 % O₂     =     0.00 %                                                    O₂       =    0.00 % HC     =      850 PPM                                                HC      =     530 PPM L        =      0.707                                                       l          =    0.769 ​ Which condition would most likely be responsible for all of the readings shown? ​

A vehicle has high levels of oxides of nitrogen (NO_x) . Which condition could be the cause?

A vehicle with high levels of oxides of nitrogen (NOx) is being discussed. Technician A says engine overheating is a likely cause. Technician B says a defective turbocharger intercooler may be the cause. Who is correct?

Normal combustion is being discussed. Technician A says water (H₂O) is a by-product of normal combustion. Technician B says carbon dioxide (CO₂) is a by-product of normal combustion. Who is correct?

​ A vehicle with a return-type fuel injection system is being tested with an exhaust gas analyzer and the following results are obtained (AIR pump disabled) : At Idle:                                                                        At 2500 RPM: CO₂  =   14.80 %                                                     CO₂   =   8.30 % CO   =    0.00 %                                                      CO     =   0.00 % O₂    =    0.20 %                                                      O₂      =    4.25 % HC   =    45 PPM                                                     HC    =    330 PPM L        =   1.007                                                           l       =    1.313 ​ Which condition would most likely be responsible for all of the readings shown? ​

Which gas is considered toxic?

​ A pre-OBD II vehicle with a return-type fuel injection system is being tested with an exhaust gas analyzer and the following results are obtained (AIR pump disabled) : At Idle:                                                            At 2500 RPM: CO₂     =    8.35 %                                           CO₂      =     7.80 % CO       =   0.00 %                                           CO       =     0.00 % O₂          =   0.91 %                                            O₂       =     0.85 % HC       =   2,150 PPM                                     HC      =     2,360 PPM L           =   0.930                                                l          =     0.908 ​ Which condition would most likely be responsible for all of the readings shown? ​

Which gas can be used an indicator of a rich condition?

Which statement is true about carbon monoxide (CO) ?

Carbon monoxide (CO) is being discussed. Technician A says carbon monoxide may cause dizziness. Technician B says carbon monoxide smells like rotten eggs.Who is correct?

A vehicle has both excessive CO and O₂ readings. Which condition is the most likely cause?

The term "stoichiometric" refers to an air fuel mixture of:

​ A vehicle with a return-type fuel injection system is being tested with an exhaust gas analyzer and the following results are obtained (AIR pump disabled) : At Idle:                                                                        At 2500 RPM: CO₂      =          8.20 %                                                 CO₂        =          14.30 % CO       =          0.00 %                                                 CO        =          0.00 % O₂          =          5.10 %                                                 O₂         =          0.25 % HC       =          1,200 PPM                                           HC       =          30 PP L           = 1.304                                                       l          =          1.01 ​ Which condition would most likely be responsible for all of the readings shown? ​

Constant volume sampling generally tests for four gasses: