Exhaust and Emission System

Question 1

What are the Two purposes of the Exhaust System?

Answer 1

1. To quiet engine operation.

2. Carry exhaust fumes to the rear of the vehicle.

Question 2

List Four major Exhaust System components.

Answer 2

1. Exhaust Manifold, 2. Header Pipe, Catalytic Converter, 4. Muffler.

Question 3

What is Exhaust Back Pressure?

Answer 3

Exhaust back pressure is developed in the exhaust system as a result of cloggage in the exhaust system. High back pressure reduces engine power and can even prevent the vehicle from starting. It can be corrected by larger pipes and free - flowing mufflers.

Question 4

What is and Advantage of a Dual Exhaust?

Answer 4

It reduces back pressure.

Question 5

What is the purpose of the oxygen sensor?

Answer 5

The oxygen sensor senses the amount of oxygen in the exhaust system and helps the ECU to determine whether the air - fuel mixture should be richer or leaner.

Question 6

What is the purpose of the Muffler (Silencer) ?

Answer 6

It reduces pressure pulses and the resulting noise from the engine.

Question 7

What is the purpose of the Catalytic Converter (Catalyst)?

Answer 7

It reduces and filters exhaust pollutants.

Question 8

What is the purpose of the Exhaust Manifold Heat Valve?

Answer 8

It forces hot exhaust gases through the exhaust passages in the intake manifold if the engine gets too hot and helps the engine warm up faster by preventing hot exhaust gas from immediately exiting the engine and by doing so, improves cold engine fuel vaporisation.

Question 9

What is the importance of Heat Shields?

Answer 9

They reduce the amount of heat transferred to the body of the car or items under the vehicle from the hot exhaust system.

Question 10

What material is the Exhaust system components made of?

Answer 10

They are made of rust resistant steel tubing.

Question 11

What is Air Pollution?

Answer 11

Air pollution is caused by an excess amount of harmful chemicals in the atmosphere.

Question 12

What is Smog?

Answer 12

Smog is a visible cloud of airborne pollutants. It is harmful to humans, animals and vegetation. It is formed when pollutants combine with oxygen and nitrogen in the presence of sunlight.

Question 13

List the Four Pollutants produced by the Engine.

Answer 13

1. Hydrocarbons, 2. Carbon Monoxide, 3. Oxides of Nitrogen, 4. Particulates.

Question 14

What is the Ideal Air to Fuel Ratio for complete Combustion in the Engine?

Answer 14

14.7 : 1

Question 15

List the Two other Vehicle Emission sources otherwise from the Engine directly.

Answer 15

1. Fuel Vaporisation

2. Crankcase Vapours.

Question 16

List the Five engine designs that can minimise emissions.

Answer 16

1. Lower Compression
2. Small Combustion Chamber Surface
3. Reduced Quench Areas
4. Decreased Valve Overlap
5. Hardened Valves and Seats.

Question 17

List the Seven Emission control systems.

Answer 17

1. Positive Crankcase ventilation.
2. Evaporative emissions control
3. Exhaust gas recirculation
4. Air Injection
5. Thermostatic air cleaner
6. Pulse
7. Catalytic Converter.

Question 18

List three aspects of the Emission control system that can be monitored using On Board Diagnostics.

Answer 18

1. Catalytic Converter Efficiency
2. Engine Misfire
3. Oxygen sensor output.

Question 19

What are the Six types of Catalytic Converters?

Answer 19

1. Monolithic
2. Pellet -type
3. Mini Catalytic Converter
4. Two - way Converter
5. Three - way Converter
6. Dual Bed Converter.

Question 20

Explain briefly the Exhaust Gas Recirculation System.

Answer 20

The Exhaust Gas Recirculation System works by allowing a small portion of the burned exhaust gases to enter the intake manifold and flow into the combustion chamber, reducing the temperatures in the combustion chamber and reducing Nitrogen Oxide emissions.