Question 1

What is applied to the ceramic substrate to make the surface porous?&#10;A)Cerium&#10;B)Washcoat&#10;C)Honeycomb filler&#10;D)Aluminum

Accepted Answer

Washcoat is applied to the ceramic substrate to increase its surface area, making it porous and more effective for supporting the catalytic materials.

Question 2

Two technicians are discussing catalytic converters. Technician A says that the exhaust mixture must fluctuate between rich and lean for the best efficiency. Technician B says that the air-fuel mixture must be leaner than 14.7:1 for best performance from a three-way catalytic converter. Which technician is correct?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Technician A only

Accepted Answer

Technician A is correct because the catalytic converter requires the exhaust mixture to oscillate around the stoichiometric point (14.7:1 air-fuel ratio) to efficiently reduce emissions. This fluctuation allows the three-way catalytic converter to convert NOx, CO, and HC effectively. Technician B is incorrect because a three-way catalytic converter operates most efficiently at a stoichiometric air-fuel ratio (14.7:1), not leaner.

Question 3

A catalytic converter has to be at least how hot before it begins to work?&#10;A)2,000 degrees F&#10;B)1,500 degrees F&#10;C)1,000 degrees F&#10;D)500 degrees F

Accepted Answer

Catalytic converters typically need to reach an operational temperature of around 500 degrees Fahrenheit (260 degrees Celsius) to effectively start the chemical reactions that reduce exhaust emissions.

Question 4

What two primary sensors does the PCM use to check the catalytic converter?&#10;A)MAP and TP&#10;B)Pre-cat and post-cat oxygen sensor&#10;C)Catalytic converter temperature sensor and rear oxygen sensor&#10;D)Pre-cat oxygen sensor and MAF

Accepted Answer

The PCM primarily uses the pre-catalytic converter (pre-cat) and post-catalytic converter (post-cat) oxygen sensors to monitor the efficiency of the catalytic converter by comparing the oxygen levels before and after the catalytic process.

Question 5

A catalytic converter can be harmed by ________.&#10;A)antifreeze&#10;B)excessive engine oil&#10;C)sulfur from poor-quality fuel&#10;D)Any of the above

Accepted Answer

Catalytic converters can be damaged by antifreeze, excessive engine oil, and sulfur from poor-quality fuel, as all these substances can lead to contamination or clogging of the converter.

Question 6

Two technicians are discussing the testing of a catalytic converter. Technician A says that a vacuum gauge can be used and observed to see if the vacuum drops with the engine at 2500 RPM for 30 seconds. Technician B says that a pressure gauge can be used to check for backpressure. Which technician is correct?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Accepted Answer

Both technicians are correct. Technician A describes a method using a vacuum gauge to observe engine vacuum behavior, which can indicate exhaust restrictions if the vacuum drops significantly. Technician B mentions using a pressure gauge to directly measure exhaust backpressure, which is a common method to check for catalytic converter efficiency and blockage.

Question 7

A catalytic converter is being tested with an infrared pyrometer. Which is an acceptable result?&#10;A)The outlet should be hotter than the inlet by 10%&#10;B)Both the inlet and outlet should be the same temperature after the converter reaches operating temperature&#10;C)The temperature of a catalytic converter is the best test to perform to locate a restricted unit&#10;D)The inlet should be hotter than the outlet by 10%

Accepted Answer

The outlet of a catalytic converter being hotter than the inlet by 10% indicates that the catalytic reaction is occurring as it should, converting harmful emissions into less harmful gases, which releases energy and increases the temperature.

Question 8

Which exhaust gas reading indicates a good catalytic converter? A)CO is zero B)O₂is zero C)Both A and B D)Neither A nor B

Accepted Answer

The answer of Which exhaust gas reading indicates a good...

Question 9

A P0422 (catalytic converter efficiency failure) is set. What is a possible cause?&#10;A)Exhaust leak&#10;B)Fuel contamination&#10;C)Engine mechanical fault&#10;D)Any of these

Accepted Answer

A P0422 code, indicating a catalytic converter efficiency failure, can be caused by various issues including exhaust leaks, fuel contamination, or engine mechanical faults. Each of these problems can lead to improper catalytic converter operation by either introducing incorrect exhaust gas composition or affecting the flow and temperature of exhaust gases.

Question 10

Technician A says that the catalytic converter is warranted for 8 years or 80,000 miles, whichever comes first. Technician B says that after replacing the catalytic converter, the old converter must be kept for possible inspection for 60 days. Which technician is correct?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Accepted Answer

The catalytic converter is federally mandated to be warranted for 8 years or 80,000 miles. Additionally, after replacement, the old converter must be kept for 60 days for possible inspection.

Question 11

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

A)Both technicians A and B
B)Technician A only
C)Technician B only
D)Neither technician A nor B

Accepted Answer

The answer of Technician A says that a converter that...

Question 12

To prevent catalytic converter damage, do not crank a flooded engine longer than ________ seconds.&#10;A)10&#10;B)60&#10;C)40&#10;D)15

Accepted Answer

The answer of To prevent catalytic converter damage, do not...

Question 13

The addition of cerium to catalytic converters provided what benefit?&#10;A)Reduction of NOx&#10;B)Purification of NOx&#10;C)Stores oxygen to help with the oxidation process&#10;D)None of these

Accepted Answer

The answer of The addition of cerium to catalytic converters...

Question 14

What term describes a catalytic converter as it reaches its effective temperature?&#10;A)Consumption&#10;B)Initiation&#10;C)Light off&#10;D)None of these

Accepted Answer

The answer of What term describes a catalytic converter as...

Question 15

Some vehicles have a &#34;mini converter.&#34; Where is this component located?&#10;A)Downstream of the main catalytic converter&#10;B)Just upstream of the muffler&#10;C)Attached directly to the exhaust manifold&#10;D)None of these

Accepted Answer

The answer of Some vehicles have a &#34;mini converter.&#34; Where...

Question 16

What is the minimum ECT temperature value required for the catalyst efficiency monitor to run under OBD-II?&#10;A)165 degrees F&#10;B)195 degrees F&#10;C)180 degrees F&#10;D)None of these

Accepted Answer

The answer of What is the minimum ECT temperature value...

Question 17

When observing O2S waveforms on a DSO on an OBD-II vehicle, which O2 sensor should have more oscillations in its O2S waveform?&#10;A)Upstream&#10;B)They will be equal&#10;C)Downstream&#10;D)None of these

Accepted Answer

The answer of When observing O2S waveforms on a DSO...

Deck 86: Catalytic Converters