CHAPTER 23 Vehicle Emission Standards and Testing

1. CHAPTER 23 Vehicle Emission Standards and Testing

2. OBJECTIVES After studying Chapter 23, 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.

3. Acceleration simulation mode (ASM) ASM 25/25 test ASM 50/15 test Federal Test Procedure (FTP) I/M 240 test Lean indicator Non-methane hydrocarbon (NMHC) Ozone Rich indicator Sealed Housing for Evaporative Determination (SHED) test Smog State Implementation Plan (SIP) KEY TERMS

4. 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. • Some of the strictest standards in the world are formulated in California by the California Air Resources Board (CARB).

5. EMISSION STANDARDS IN THE UNITED STATES • TIER 1 AND TIER 2 • TLEV Transitional Low-Emission Vehicle • LEV Low-Emission Vehicle • ULEV 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

6. FIGURE 23–1 The underhood decal showing that this Lexus RX-330 meets both national (Tier 2; BIN 5) and California LEV-II (ULEV) regulation standards. EMISSION STANDARDS IN THE UNITED STATES

7. EMISSION STANDARDS IN THE UNITED STATES • FEDERAL EPA BIN NUMBER • SMOG EMISSION INFORMATION • CALIFORNIA STANDARDS

8. EMISSION STANDARDS IN THE UNITED STATES

9. EMISSION STANDARDS IN THE UNITED STATES

10. EMISSION STANDARDS IN THE UNITED STATES

11. FIGURE 23–2 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. EMISSION STANDARDS IN THE UNITED STATES

12. 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+)

13. EXHAUST ANALYSIS TESTING • The Clean Air Act Amendments require enhanced I/M programs in areas of the country that have the worst air quality and the Northeast Ozone Transport region. • The states must submit to the EPA a State Implementation Plan (SIP) for their programs.

14. EXHAUST ANALYSIS TESTING • Each enhanced I/M program is required to include as a minimum the following items: • Computerized emission analyzers • Visual inspection of emission control items • Minimum waiver limit (to be increased based on the inflation index) • Remote on-road testing of one-half of 1% of the vehicle population • Registration denial for vehicles not passing an I/M test • Denial of waiver for vehicles that are under warranty or that have been tampered with • Annual inspections • OBD-II systems check for 1996 and newer vehicles

15. 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

16. FIGURE 23–3 Photo of a sign taken at an emissions test facility. EXHAUST ANALYSIS TESTING

17. FIGURE 23–4 A vehicle being tested during an enhanced emission test. EXHAUST ANALYSIS TESTING

18. FIGURE 23–5 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. EXHAUST ANALYSIS TESTING

19. 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. • The five gases analyzed and their significance include:

20. FIGURE 23–6 A partial stream sampling exhaust probe being used to measure exhaust gases in parts per million (PPM) or percent (%). EXHAUST ANALYSIS AND COMBUSTION EFFICIENCY

21. EXHAUST ANALYSIS AND COMBUSTION EFFICIENCY • The five gases analyzed and their significance include: • HYDROCARBONS • CARBON MONOXIDE • CARBON DIOXIDE (CO2) • OXYGEN • OXIDES OF NITROGEN (NOX)

22. FIGURE 23–7 Exhaust emissions are very complex. When the air–fuel mixture becomes richer, some exhaust emissions are reduced, while others increase. EXHAUST ANALYSIS AND COMBUSTION EFFICIENCY

23. How Can My Worn-Out, Old, High-Mileage Vehicle Pass an Exhaust Emission Test? • Age and mileage of a vehicle are generally not factors when it comes to passing an exhaust emission test. Regular maintenance is the most important factor for passing an enhanced Inspection and Maintenance (I/M) exhaust analysis test. Failure of the vehicle owner to replace broken accessory drive belts, leaking air pump tubes, defective spark plug wires, or a cracked exhaust manifold can lead to failure of other components such as the catalytic converter. Tests have shown that if the vehicle is properly cared for, even an engine that has 300,000 miles (483,000 km) can pass an exhaust emission test.

24. HC TOO HIGH • High hydrocarbon exhaust emissions are usually caused by an engine misfire. What burns the fuel in an engine? • The ignition system ignites a spark at the spark plug to ignite the proper mixture inside the combustion chamber. • If a spark plug does not ignite the mixture, the resulting unburned fuel is pushed out of the cylinder on the exhaust stroke by the piston through the exhaust valves and into the exhaust system.

25. HC TOO HIGH • Therefore, if any of the following ignition components or adjustments are not correct, excessive HC emission is likely. • 1. Defective or worn spark plugs • 2. Defective or loose spark plug wires • 3. Defective distributor cap and/or rotor • 4. Incorrect ignition timing (either too far advanced or too far retarded) • 5. A lean air–fuel mixture can also cause a misfire. This condition is referred to as a lean misfire. A lean air-fuel mixture can be caused by low fuel pump pressure, a clogged fuel filter or a restricted fuel injector.

26. CO TOO HIGH • Excessive carbon monoxide is an indication of too rich an air–fuel mixture. CO is the rich indicator. • The higher the CO reading, the richer the air–fuel mixture. • High concentrations of CO indicate that not enough oxygen was available for the amount of fuel. • Common causes of high CO include: • Too-high fuel-pump pressure • Defective fuel-pressure regulator • Clogged air filter or PCV valve • Defective injectors

27. CO Equals O2 • If the exhaust is rich, CO emissions will be higher than normal. If the exhaust is lean, O2 emissions will be higher than normal. Therefore, if the CO reading is the same as the O2 reading, then the engine is operating correctly. For example, if both CO and O2 are 0.5% and the engine develops a vacuum leak, the O2 will rise. If a fuel-pressure regulator were to malfunction, the resulting richer air–fuel mixture would increase CO emissions. Therefore, if both the rich indicator (CO) and the lean indicator (O2) are equal, the engine is operating correctly.

28. MEASURING OXYGEN (O2) AND CARBON DIOXIDE (CO2) • Two gas exhaust analyzers (HC and CO) work well, but both HC and CO are consumed (converted) inside the catalytic converter. • 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%.

29. How to Find a Leak in the Exhaust System • A hole in the exhaust system can dilute the exhaust gases with additional oxygen (O2). This additional O2 in the exhaust can lead the service technician to believe that the air–fuel mixture is too lean. To help identify an exhaust leak, perform an exhaust analysis at idle and at 2500 RPM (fast idle) and compare with the following: • If the O2 is high at idle and at 2500 RPM, the mixture is lean at both idle and at 2500 RPM. • If the O2 is low at idle and high at 2500 RPM, this usually means that the vehicle is equipped with a working AIR pump. • If the O2 is high at idle, but okay at 2500 RPM, a hole in the exhaust or a small vacuum leak that is “covered up” at higher speed is indicated.

30. FIGURE 23–8 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. How to Find a Leak in the Exhaust System

31. Your Nose Knows • Using the nose, a technician can often identify a major problem without having to connect the vehicle to an exhaust analyzer. For example, • The strong smell of exhaust is due to excessive unburned hydrocarbon (HC) emissions. • If your eyes start to burn or water, suspect excessive oxides of nitrogen (NOX) emissions. • Dizzy feeling or headache.

32. PHOTOCHEMICAL SMOG FORMATION • Oxides of nitrogen are formed by high temperature—over 2500°F (1370°C)—and/or pressures inside the combustion chamber. • Oxides of nitrogen contribute to the formation of photochemical smog when sunlight reacts chemically with NOX and unburned hydrocarbons (HC). • Smog is a term derived by combining the words smoke and fog. • Ground-level ozone is a constituent of smog.

33. PHOTOCHEMICAL SMOG FORMATION • Ozone is an enriched oxygen molecule with three atoms of oxygen (O3) instead of the normal two atoms of oxygen (O2). • Ozone in the upper atmosphere is beneficial because it blocks out harmful ultraviolet rays that contribute to skin cancer. • However, at ground level, this ozone (smog) is an irritant to the respiratory system.

34. 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.

35. TESTING FOR OXIDES OF NITROGENSPECIFICATIONS 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.

36. Check for Dog Food? • A commonly experienced problem in many parts of the country involves squirrels or other animals placing dog food into the air intake ducts of vehicles. Dog food is often found packed tight in the ducts against the air filter. An air intake restriction occurs and drives the fuel mixture richer than normal and reduces engine power and vehicle performance as well as creating high CO exhaust emissions.

37. The Case of the Retarded Exhaust Camshaft • A Toyota equipped with a double overhead camshaft (DOHC) inline six-cylinder engine failed the statemandated enhanced exhaust emission test for NOX. The engine ran perfectly without spark knocking (ping), which is usually a major reason for excessive NOX emissions. The technician checked the following: • The ignition timing, which was found to be set to specifications (if too far advanced, can cause excessive NOX) • The cylinders, which were decarbonized using top engine cleaner • The EGR valve, which was inspected and the EGR passages cleaned

38. The Case of the Retarded Exhaust Camshaft • After all the items were completed, the vehicle was returned to the inspection station where the vehicle again failed for excessive NOX emissions (better, but still over the maximum allowable limit). • After additional hours of troubleshooting, the technician decided to go back to basics and start over again. A check of the vehicle history with the owner indicated that the only previous work performed on the engine was a replacement timing belt over a year before.

39. The Case of the Retarded Exhaust Camshaft • The technician discovered that the exhaust cam timing was retarded two teeth, resulting in late closing of the exhaust valve. The proper exhaust valve timing resulted in a slight amount of exhaust being retained in the cylinder. This extra exhaust was added to the amount supplied by the EGR valve and helped reduce NOX emissions. After repositioning the timing belt, the vehicle passed the emissions test well within the limits.

40. O2S Shows Rich, but Pulse Width Is Low • A service technician was attempting to solve a driveability problem. The computer did not indicate any diagnostic trouble codes (DTCs). A check of the oxygen sensor voltage indicated a higher-than-normal reading almost all the time. The pulse width to the port injectors was lower than normal. The lower-than-normal pulse width indicates that the computer is attempting to reduce fuel flow into the engine by decreasing the amount of on-time for all the injectors.

41. O2S Shows Rich, but Pulse Width Is Low • What could cause a rich mixture if the injectors were being commanded to deliver a lean mixture? Finally the technician shut off the engine and took a careful look at the entire fuel-injection system. Although the vacuum hose was removed from the fuel-pressure regulator, fuel was found dripping from the vacuum hose. The problem was a defective fuelpressure regulator that allowed an uncontrolled amount of fuel to be drawn by the intake manifold vacuum into the cylinders. While the computer tried to reduce fuel by reducing the pulse width signal to the injectors, the extra fuel being drawn directly from the fuel rail caused the engine to operate with too rich an air–fuel mixture.

42. 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).

43. 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.

44. 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.

45. CHAPTER QUIZ 1. 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

46. 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

47. 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

48. 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

49. 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

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