Systems Repair Worksheet



Systems Repair Worksheet Chapter 33 Pages 978-1008 Name      

Emission Control Systems 62 Points Due Date      

1. The emission control systems on today’s vehicles are an part of the engine and

the electronic engine control system (EEC).

2. HC or are the result of either incomplete burning (misfire) or evaporation.

3. CO or results from burning overly rich A/F mixtures.

4. NOx or result from burning at high temperatures & pressures.

5. In stagnant air, when exposed to sunlight, HC & NOx react to form .

6. O2 is an exhaust gas, but it is not considered to be a . (good diagnostic gas)

7. SO2 evidenced by a smell in the exhaust is not a “regulated” pollutant.

8. CO2 or is a greenhouse gas and an indicator of good combustion.

9. should be emitted from a vehicle’s exhaust. It is a byproduct of good combustion.

Note: An engine will create about a gallon of water for every gallon of gasoline burned.

10. A diesel engine will emit , which is a form of carbon-based particulate emissions.

11. The history of emission controls & the EPA began with the

(CARB) and the of 1963. It continues strong today

with emission standards being one of the driving forces behind technological changes in vehicles.

12. Many states have periodic vehicle emission & (I/M) programs.

13. Vehicles must have a Vehicle Emission Control Information (VECI) under the hood.

14. Complete the chart about emission control systems & devices by circling the choices:

Abbreviation Full Name Type Pollutants Lowered

|TAC | | | |

|*EGR | | | |

|*EVAP | | | |

|EFE | | | |

~~~~~~

|*CAT | | | |

|AIR | | | |

|*PVC | | | |

15. The system reduces the

amount of raw fuel vapors emitted into the air.

16. The charcoal or carbon catches fuel vapors and through the valve,

controls their release into the engine to be burned during closed loop.

17. An Evaporative Emission System can conduct self-tests to detect leaks as small as

.020” and can also monitor canister purge flow. (.020” = large leak)

18. Enhanced EVAP systems use a Pressure senor (FTP) and a canister vent

solenoid in addition to regular parts to run the EVAP diagnostic monitor tests.

19. Systems designed to or limit the amount of pollutants produced by an engine are

called pre-combustion emission controls.

20. Engine design changes like better sealing , more efficient combustion

designs, lower compression ratios, decreased friction, better manifold designs, improved cooling

systems and more accurate spark control systems all increase efficiency & lower pollution.

21. The system brings filtered, fresh air into the crankcase to mix with gasses

which are then routed into the intake manifold and mixed with incoming A/F to be burned.

22. A malfunctioning PCV system will allow engine oil to form, will cause HC dilution

of the engine oil, and will cause seal & gasket leaks from an overly pressurized crankcase.

23. The is the main component in the crankcase ventilation system.

24. Some engines have electrically PCV valves to stop moisture from freezing them.

25. The system dilutes the A/F mixture with controlled amounts of inert exhaust gas in an

effort to lower peak combustion chamber temperatures and prevent oxides of nitrogen emissions.

26. Too EGR flow can cause driveability, starting & idling problems.

27. EGR systems can be eliminated & NOx pollution controlled with valve timing.

28. EGR valve operation can be by an EGR vacuum regulator, which is a pulse-

width modulated solenoid operated by the PCM. The EVR controls EGR on-time.

29. A EGR sensor/system (DPFE) is used

to verify that if the EGR valve was commanded on, it actually did its job. MAP can be used too.

30. Engines with carburetors or throttle body injection used (EFE)

heater grids in the intake manifold or devices known as heat risers to warm the intake manifold.

31. Systems designed to clean up or remedy the after the fuel has been burned but

before the gases exit the tailpipe are called post-combustion emission controls.

32. The (CAT) contains 2 or more

elements (biscuits) coated with catalysts that cause a

chemical reaction to “clean” the exhaust.

33. The 1st bed in a CAT has a rhodium catalyst to reduce into

just Nitrogen and just Oxygen. (reduction = de-oxidation)

34. The 2nd bed in a CAT uses & catalysts to oxidize HC & CO,

turning them into H2O & CO2. A Cerium catalyst is also used to store oxygen in the CAT.

35. The system (AIR) adds fresh air into the exhaust stream while it’s

still in the exhaust manifold to further oxidize the HC and CO in the exhaust.

36. Either -driven AIR pumps, electric AIR pumps, or Pulse-AIR systems are used as this

source of “secondary air” to reduce HC & CO emissions. Air switching diverter valves control flow.

37. Secondary air systems can air upstream to the exhaust manifold or downstream to the CAT.

38. Clean diesel engines that use low fuel are also fit with EGR & PCV systems.

39. filters (traps) & catalytic converters are types of diesel “after treatment” systems.

40. Diesel engines cleaned up their exhaust through OBD-II engine controls and common

electronic fuel injection with high pressure piezoelectric direct injectors.

41. Diesel engines use , which are small electric heater elements threaded right

into the combustion chamber to quickly warm it for extremely cold starting conditions.

42. The diesel PCV system is called (CDR).

43. Diesel engines use EGR to lower combustion chamber temperatures, and also the

exhaust gas before it re-enters the engine. (EGR Cooler)

44. Diesel engines use traps after the catalytic converter to catch soot.

45. Diesel Selective Catalytic Reduction (SCR) systems inject (dose) a liquid into the

exhaust stream that is absorbed onto a catalyst which in turn cleans up NOx emissions.

46. The common reductants used in SCR systems are and .

47. SCR reductants are kept in heated, plastic reservoirs & get filled about as often as the fuel tank.

48. Honda has built a CAT that produces its own to be used as a diesel SCR reductant.

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