Week 4, Light Duty Diesel Emissions

Question 1

• Liquid and solid particles emitted from the engine exhaust and crankcase
• Black carbon results in soot emissions; eliminated with newer diesel engines
• Regulated and classified by particulate size in four categories

Answer 1

Particulate Matter

Question 2

Chassis ________________ measure emissions based on distance travelled by the complete vehicle

Answer 2

Dynamometers

Question 3

What is a common method to measure smoke density of diesel engine exhaust?

Answer 3

Opacity Testing

Question 4

• Inadequate combustion time
• Improperly mixed fuel and air
• Coarse spray droplets
• Insufficient combustion heat
• Fuel pressure too low

These are all common causes of…

Answer 4

Incomplete combustion

Question 5

Regulating _______ (a naturally occurring component in diesel fuel), it enables sophisticated exhaust emissions’ aftertreatment

Answer 5

Sulfur

Question 6

High fuel sulfur content destroys ability of sulfate production devices to convert _________ emissions to __________ emissions

Answer 6

Noxious (harmful); Nonharmful

Question 7

Diesel engines are governed at relatively ____ engine speeds

Answer 7

Low

Question 8

First standards to reduce diesel emissions were introduced in _______

Answer 8

1970

Question 9

Diesel fuel sulfur content was reduced to __% in 1993

Answer 9

1

Question 10

Prior to 2007, emission reduction was accomplished in the ______________

Answer 10

Cylinder

Question 11

• Indicate the level of emission standard an engine was designed to achieve
• Provides information about part replacement and adjustment procedures, software calibration files, and other relevant data that affects emissions

Answer 11

Emissions Decals

Question 12

• Light duty: 110,000 miles or 10 years
• Medium duty: 185,000 miles of 10 years
• Heavy duty: 435,000 miles or 10 years

These are all examples of…

Answer 12

Useful life requirements

Question 13

• Low and high pressure cooled EGR
• Two-way oxidation converters
• Diesel particulate filters
• Etc.

These are all examples of…

Answer 13

EPA-07 Standards

Question 14

From 2004-2010, NOx emissions had to be reduced by _____

Answer 14

90%

Question 15

The biggest technical challenges with diesel catalysts are…

Answer 15

• Cold exhaust temperatures
• Excess air content in exhaust

Question 16

A(n) _________________________________ causes oxygen to chemically combine with noxious emissions such as HC and CO

Answer 16

Oxidation catalytic converter

Question 17

_____________________ systems were introduced to help achieve a 90% reduction in NOx emissions

Answer 17

Selective catalytic reduction

Question 18

Oxidation process turns emissions into _____________

Answer 18

Water

Question 19

Oxidation converters consist of a stainless-steel canister called a _____________

Answer 19

Substrate

Question 20

Substrate in a catalyst has a washcoat of catalytic ________________________

Answer 20

Precious metals

Question 21

Diesel catalysts need a minimum temperature of _______ before O2 can oxidize

Answer 21

400°F

Question 22

Reduction of pungent diesel odor is a ______________

Answer 22

Byproduct

Question 23

Exhaust is diluted with air, which _________________ its temperature

Answer 23

Reduces

Question 24

Technology incorporates HC-trapping materials into a catalyst substrate called _______________

Answer 24

Zeolite

Question 25

Low-temperature oxidation catalysts begin to catalyze at approximately _______

Answer 25

360°F

Question 26

What component removes soot and other solid particles from diesel exhaust, rendering the exhaust completely smokeless?

Answer 26

DPF (Diesel Particulate Filter)

Question 27

DPF's eliminate particles down to ___ nanometers

Answer 27

50

Question 28

Exhaust passed through a wall _____________ where gas can escape but PM is trapped

Answer 28

Flow filter

Question 29

When DPF's eventually become clogged, _______________ clears out the filter

Answer 29

Regeneration

Question 30

Heat for regeneration either comes from ________________ or __________________

Answer 30

Exhaust gas; added fuel

Question 31

_________ Regeneration - Takes place 85% of the time - No fuel is added - Vehicle must be 30+mph for 20 minutes

Answer 31

Passive

Question 32

The DPF is heated by adding small amounts of fuel to the exhaust stream. A downstream oxidation converter produces heat through a catalytic reaction of the fuel

Answer 32

Active regeneration

Question 33

In active regeneration, exhaust temperatures can raise to over _______

Answer 33

1000°F

Question 34

A fault code is set when a soot load of ____ is reached

Answer 34

80%

Question 35

Late injection in the exhaust stroke can cause ___________ in engine oil

Answer 35

Fuel dilution

Question 36

__________ regeneration requires vehicle to be away from combustible material

Answer 36

Parked

Question 37

DPF catalyst substrate is available in different materials such as...

Answer 37

- Cordierite - Silicon carbide - Metal foil

Question 38

What can accumulate inside a DPF? (result of burned oil)

Answer 38

Ash

Question 39

What is the process called where liquid urea is sprayed into exhaust stream to destroy NOx molecules?

Answer 39

SCR (Selective Catalytic Reduction)

Question 40

NOx ______________________ is a catalyst strategy for removing NOx in the low-temperature, oxygen-rich exhaust environment of diesel engines

Answer 40

Absorber technology

Question 41

Lean NOx refers to __________________

Answer 41

Oxygen content

Question 42

The process in which NOx emissions are temporarily stored in the catalyst and removed in a two-step process that introduces fuel-rich oxygen-depleted exhaust

Answer 42

NOx Adsorbing

Question 43

What are the two drawbacks in DeSOx reactions?

Answer 43

- NAC aftertreatment requires increased fuel consumption - Sulfur deactivates NACs

Question 44

A variety of ______ are needed to make DPFs work

Answer 44

Sensors

Question 45

Which sensor measures exhaust pressure at DPF inlet and outlet and supplies that data to the ECM?

Answer 45

Differential pressure sensor

Question 46

Most DPFs use _______ temperature sensor

Answer 46

Three

Question 47

____ sensors do not provide closed-loop feedback to meter the correct amount of DEF, but can detect incorrect concentrations of DEF emitted by dosing injectors and other emission related faults

Answer 47

NOx

Question 48

What component produces NH3 in the engine exhaust using HC dosing, high EGR flow, and reduced oxygen content without fluid additives?

Answer 48

NAN/LNT components

Question 49

- When DPF soot loading exceeds 80%, the driver should change driving conditions to initiate a DPF passive regeneration - If passive regeneration cannot be completed, an active regeneration must be done - Engine must e warm and left at low idle, parking brake applied, and DPF inhibit switch held These are all necessary when performing an...

Answer 49

Active Regeneration Procedure

Question 50

- Initiated using an electronic service tool or OEM software - Light-duty vehicles cannot be regenerated by dash switches - Heavy-duty vehicles may not be able to complete active regenerations These are all necessary when performing a...

Answer 50

Forced DPF Regeneration

Question 51

____ will accumulate from engine oil and eventually DPF will need to be removed for service

Answer 51

Ash

Question 52

_________________________ is a major emission problem in diesel engines due to higher compression ratios, cylinder pressure, and temperatures

Answer 52

NOx formation

Question 53

EGR may incorporate the use of a ________________ to help draw in EGR gases

Answer 53

Throttle plate

Question 54

Provide the ECM with data about quantity of air and exhaust, conditions that enable and disable EGR flow, and diagnostic data for the OBD system

Answer 54

EGR System Input Sensors

Question 55

Engine speed and accelerator pedal position indicate how much EGR mass is required for engine; combined with intake manifold pressure and temperature and determines the weight of air entering the cylinders

Answer 55

EGR Mass calculations

Question 56

The OBD II system detects and measures whether correct EGR flow is enabled based on a reduction in airflow into the engine

Answer 56

MAF Sensor and EGR Flow Calculations

Question 57

EGR gas flows through a venturi, which has a sensor measuring the pressure on its inlet and outlet sides. Low flow produces a low differential, high flow produces a high differential. Combined with gas temperature data, an accurate measure of EGR flow can be achieved.

Answer 57

Pressure Differential Measurement of EGR Flow

Question 58

Exhaust gas temperature must be lowered to roughly 425°F before it enters the cylinder. An EGR cooler is a heat exchanger that transfers heat from EGR gas to the cooling system. All cooling system components must be able to withstand the additional heat load

Answer 58

EGR Coolers

Question 59

What tools are required for diagnosing an external, non-cooled EGR?

Answer 59

1. Vacuum gauge 2. Multimeter 3. Scan tool