OBJECTIVES - PowerPoint PPT Presentation

slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
OBJECTIVES PowerPoint Presentation
play fullscreen
1 / 45
OBJECTIVES
178 Views
Download Presentation
erasmus
Download Presentation

OBJECTIVES

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. OBJECTIVES After studying Chapter 25, the reader will be able to: • Prepare for ASE A8 certification test content area “D” (Emissions Control Systems Diagnosis and Repair) and ASE L1 certification test content area “F” (I/M Failure Diagnosis). • Discuss emission standards. • Identify the reasons why excessive amounts of HC, CO, and NOX exhaust emissions are created. • Describe how to baseline a vehicle after an exhaust emission failure. • List acceptable levels of HC, CO, CO2, and O2 with and without a catalytic converter. • List four possible causes for high readings for HC, CO, and NOX.

  2. EMISSION STANDARDS IN THE UNITED STATES • In the United States, emissions standards are managed by the Environmental Protection Agency (EPA) as well as some U.S. state governments. • Tier 1 and Tier 2 • TLEV—Transitional Low-Emission Vehicle. • LEV—(also known as: LEV I) Low-Emission Vehicle. • ULEV (also known as ULEV I)—Ultra-Low-Emission Vehicle. • ULEV II—Ultra-Low-Emission Vehicle. • SULEV—Super-Ultra-Low-Emission Vehicle. • ZEV—Zero-Emission Vehicle. • PZEV—Partial Zero-Emission Vehicle. • ILEV—Inherently Low-Emission Vehicle. • AT-PZEV—Advanced Technology Partial Zero-Emission Vehicle. • NLEV—National Low-Emission Vehicle.

  3. EMISSION STANDARDS IN THE UNITED STATES FIGURE 25-1 The underhood decal showing that this Lexus RX-330 meets both national (Tier 2; BIN 5) and California LEV-II (ULEV) regulation standards.

  4. EMISSION STANDARDS IN THE UNITED STATESFederal EPA Bin Number • The higher the tier number, the newer the regulation; the lower the bin number, the cleaner the vehicle. • The 2004 Toyota Prius is a very clean Bin 3, while the Hummer H2 is a dirty Bin 11. TABLE 25-1 EPA Tier 2—120,000-Mile Tailpipe Emission Limits. The highest bin number allowed after January 1, 2007, is Bin 8

  5. EMISSION STANDARDS IN THE UNITED STATESFederal EPA Bin Number TABLE 25-2 Air Pollution Score U.S.EPA Vehicle Information Program (The Higher the Score, the Lower the Emissions)

  6. EMISSION STANDARDS IN THE UNITED STATESFederal EPA Bin Number TABLE 25-3 Greenhouse Gas Score

  7. EMISSION STANDARDS IN THE UNITED STATESSmog Emission Information • New vehicles are equipped with a sticker that shows the relative level of smog-causing emissions created by the vehicle compared to others on the market. • Smog-causing emissions include unburned hydrocarbons (HC) and oxides of nitrogen (NOX). FIGURE 25-2 This label on a Toyota Camry hybrid shows the relative smog-producing emissions, but this does not include carbon dioxide (CO2), which may increase global warming.

  8. EMISSION STANDARDS IN THE UNITED STATESCalifornia Standards • The pre-2004 California Air Resources Board (CARB) standards as a whole were known as LEV I. • Within that, there were four possible ratings: Tier 1, TLEV, LEV, and ULEV. • The newest CARB rating system (since January 1, 2004) is known as LEV II.

  9. EUROPEAN STANDARDS • Europe has its own set of standards that vehicles must meet, which includes the following tiers: • Euro I (1992–1995) • Euro II (1995–1999) • Euro III (1999–2005) • Euro IV (2005–2008) • Euro V (2008) • Vehicle emission standards and technological advancements have successfully reduced pollution from cars and trucks by about 90% since the 1970s. • Unfortunately, there currently are more vehicles on the road and they are being driven more miles each year, partially offsetting the environmental benefits of individual vehicle emissions reductions.

  10. EXHAUST ANALYSIS TESTING • Federal Test Procedure (FTP) • I/M Test Programs • Visual Tampering Checks • One-Speed and Two-Speed Idle Test • Loaded Mode Test • Acceleration Simulation Mode (ASM) • I/M 240 Test • OBD-II Testing • Remote Sensing • Random Roadside Testing

  11. EXHAUST ANALYSIS TESTING FIGURE 25-3 Photo of a sign taken at an emissions test facility.

  12. EXHAUST ANALYSIS TESTING FIGURE 25-4 A vehicle being tested during an enhanced emission test.

  13. EXHAUST ANALYSIS TESTING FIGURE 25-5 Trace showing the Inspection/Maintenance 240 test. The test duplicates an urban test loop around Los Angeles, California. The first “hump” in the curve represents the vehicle being accelerated to about 20 MPH, then driving up a small hill to about 30 MPH and coming to a stop. At about 94 seconds, the vehicle stops and again accelerates while climbing a hill and speeding up to about 50 MPH during this second phase of the test.

  14. EXHAUST ANALYSIS AND COMBUSTION EFFICIENCY • A popular method of engine analysis, as well as emission testing, involves the use of five-gas exhaust analysis equipment. FIGURE 25-6 A partial stream sampling exhaust probe being used to measure exhaust gases in parts per million (PPM) or percent (%).

  15. EXHAUST ANALYSIS AND COMBUSTION EFFICIENCY • Hydrocarbons • Carbon Monoxide • Carbon Dioxide (CO2) • Oxygen • Oxides of Nitrogen (NOX) FIGURE 25-7 Exhaust emissions are very complex. When the air-fuel mixture becomes richer, some exhaust emissions are reduced, while others increase.

  16. HC TOO HIGH • If any of the following ignition components or adjustments are not correct, excessive HC emission is likely. • Defective or worn spark plugs • Defective or loose spark plug wires • Defective distributor cap and/or rotor • Incorrect ignition timing (either too far advanced or too far retarded) • A lean air-fuel mixture can also cause a misfire. This condition is referred to as a lean misfire.

  17. CO TOO HIGH • Common causes of high CO include: • Too-high fuel-pump pressure • Defective fuel-pressure regulator • Clogged air filter or PCV valve • Defective injectors

  18. MEASURING OXYGEN (O2) AND CARBON DIOXIDE (CO2) • The amount of leftover oxygen coming out of the tailpipe is an indication of leanness. • The higher the O2 level, the leaner the exhaust. • Oxygen therefore is the lean indicator. • Acceptable levels of O2 are 0% to 2%. • Carbon dioxide (CO2) is a measure of efficiency. • The higher the level of CO2 in the exhaust stream, the more efficiently the engine is operating.

  19. HOW TO FIND A LEAK IN THE EXHAUST SYSTEM FIGURE 25-8 A hole in the exhaust system can cause outside air (containing oxygen) to be drawn into the exhaust system. This extra oxygen can be confusing to a service technician because the extra O2 in the exhaust stream could be misinterpreted as a too-lean air fuel mixture.

  20. PHOTOCHEMICAL SMOG FORMATION • Oxides of nitrogen contribute to the formation of photochemical smog when sunlight react chemically with NOX and unburned hydrocarbons (HC). • Smog is a term derived by combining the words smoke and fog.

  21. TESTING FOR OXIDES OF NITROGEN • Because the formation of NOX occurs mostly under load, the most efficient method to test for NOX is to use a portable exhaust analyzer that can be carried in the vehicle while the vehicle is being driven under a variety of conditions. • Specifications for NOX • From experience, a maximum reading of 1,000 parts per million (PPM) of NOX under loaded driving conditions will generally mean that the vehicle will pass an enhanced I/M roller test. • A reading of over 100 PPM at idle should be considered excessive.

  22. SUMMARY • Excessive hydrocarbon (HC) exhaust emissions are created by a lack of proper combustion such as a fault in the ignition system, too lean an air-fuel mixture, or too cold engine operation. • Excessive carbon monoxide (CO) exhaust emissions are usually created by a rich air-fuel mixture. • Excessive oxides of nitrogen (NOX) exhaust emissions are usually created by excessive heat or pressure in the combustion chamber or a lack of the proper amount of exhaust gas recirculation (EGR).

  23. SUMMARY • Carbon dioxide (CO2) levels indicate efficiency. The higher the CO2, the more efficient the engine operation. • Oxygen (O2) indicates leanness. The higher the O2, the leaner the air-fuel mixture. • A vehicle should be driven about 20 miles, especially during cold weather, to allow the engine to be fully warm before an enhanced emissions test.

  24. REVIEW QUESTIONS • List the five exhaust gases and their maximum allowable readings for a fuel-injected vehicle equipped with a catalytic converter. • List two causes of a rich exhaust. • List two causes of a lean exhaust. • List those items that should be checked if a vehicle fails an exhaust test for excessive NOX emissions.

  25. CHAPTER QUIZ • Technician A says that high HC emission levels are often caused by a fault in the ignition system. Technician B says that high CO2 emissions are usually caused by a richer-than-normal air-fuel mixture. Which technician is correct? • Technician A only • Technician B only • Both Technicians A and B • Neither Technician A nor B

  26. CHAPTER QUIZ • Technician A says that high HC emission levels are often caused by a fault in the ignition system. Technician B says that high CO2 emissions are usually caused by a richer-than-normal air-fuel mixture. Which technician is correct? • Technician A only • Technician B only • Both Technicians A and B • Neither Technician A nor B

  27. CHAPTER QUIZ 2. HC and CO are high and CO2 and O2 are low. This could be caused by a _____. • Rich mixture • Lean mixture • Defective ignition component • Clogged EGR passage

  28. CHAPTER QUIZ 2. HC and CO are high and CO2 and O2 are low. This could be caused by a _____. • Rich mixture • Lean mixture • Defective ignition component • Clogged EGR passage

  29. CHAPTER QUIZ 3. Which gas is generally considered to be the rich indicator? (The higher the level of this gas, the richer the air-fuel mixture.) • HC • CO • CO2 • O2

  30. CHAPTER QUIZ 3. Which gas is generally considered to be the rich indicator? (The higher the level of this gas, the richer the air-fuel mixture.) • HC • CO • CO2 • O2

  31. CHAPTER QUIZ 4. Which gas is generally considered to be the lean indicator? (The higher the level of this gas, the leaner the air-fuel mixture.) • HC • CO • CO2 • O2

  32. CHAPTER QUIZ 4. Which gas is generally considered to be the lean indicator? (The higher the level of this gas, the leaner the air-fuel mixture.) • HC • CO • CO2 • O2

  33. CHAPTER QUIZ 5. Which exhaust gas indicates efficiency? (The higher the level of this gas, the more efficient the engine operates.) • HC • CO • CO2 • O2

  34. CHAPTER QUIZ 5. Which exhaust gas indicates efficiency? (The higher the level of this gas, the more efficient the engine operates.) • HC • CO • CO2 • O2

  35. CHAPTER QUIZ 6. All of the gases are measured in percentages except _____. • HC • CO • CO2 • O2

  36. CHAPTER QUIZ 6. All of the gases are measured in percentages except _____. • HC • CO • CO2 • O2

  37. CHAPTER QUIZ 7. After the following exhaust emissions were measured, how was the engine operating? HC = 766 PPM CO2 = 8.2% CO = 4.6% O2 = 0.1% • Too rich • Too lean

  38. CHAPTER QUIZ 7. After the following exhaust emissions were measured, how was the engine operating? HC = 766 PPM CO2 = 8.2% CO = 4.6% O2 = 0.1% • Too rich • Too lean

  39. CHAPTER QUIZ 8. Technician A says that carbon inside the engine can cause excessive NOX to form. Technician B says that excessive NOX could be caused by a cooling system fault causing the engine to operate too hot. Which technician is correct? • Technician A only • Technician B only • Both Technicians A and B • Neither Technician A nor B

  40. CHAPTER QUIZ 8. Technician A says that carbon inside the engine can cause excessive NOX to form. Technician B says that excessive NOX could be caused by a cooling system fault causing the engine to operate too hot. Which technician is correct? • Technician A only • Technician B only • Both Technicians A and B • Neither Technician A nor B

  41. CHAPTER QUIZ 9. A clogged EGR passage could cause excessive _____ exhaust emissions. • HC • CO • NOX • CO2

  42. CHAPTER QUIZ 9. A clogged EGR passage could cause excessive _____ exhaust emissions. • HC • CO • NOX • CO2

  43. CHAPTER QUIZ 10. An ignition fault could cause excessive _____ exhaust emissions. • HC • CO • NOX • CO2

  44. CHAPTER QUIZ 10. An ignition fault could cause excessive _____ exhaust emissions. • HC • CO • NOX • CO2