Chapter 61

[object Object],[object Object],[object Object],OBJECTIVES: After studying Chapter 61, the reader should be able to: Continued

[object Object],[object Object],OBJECTIVES: After studying Chapter 61, the reader should be able to:

EMISSION STANDARDS IN THE UNITED STATES ,[object Object],Continued

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Figure 61–1 The underhood decal showing that this Lexus RX-330 meets both national Tier 2; BIN 5) and California LEV-II (ULEV) regulation standards. Continued NOTE: A battery-powered electric vehicle charged from the power grid will still be up to 10 times cleaner than even the cleanest gasoline vehicles over their respective lifetimes.

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[object Object],Continued See the table on Page 734 of your textbook.

See the tables on Page 735 of your textbook.

[object Object],Figure 61–2 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. Continued Federal 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.

EUROPEAN STANDARDS ,[object Object],Continued ,[object Object],[object Object],[object Object],[object Object],[object Object],Vehicle emission standards and technological advancements have successfully reduced pollution from cars and trucks by about 90% since the 1970s.

EXHAUST ANALYSIS TESTING ,[object Object],Continued ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Continued

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[object Object],Continued NOTE: A SHED is constructed entirely of stainless steel. The walls, floors, and ceiling, plus the door, are all constructed of stainless steel because it does not absorb hydrocarbons, which could offset test results.

[object Object],Figure 61–3 Photo of a sign taken at an emissions test facility. Continued Each state is free to develop a testing program suitable to their needs as long as they achieve the attainment levels set by the EPA. This approach has led to a variety of different testing programs.

[object Object],Continued ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],If any of these systems are missing, not connected, or tampered with, the vehicle will fail the emissions test and will have to be repaired/replaced by the vehicle owner before the vehicle can pass the emission test.

[object Object],Figure 61–4 A vehicle being tested during an enhanced emission test. Continued Conventional stand-alone sampling equipment is used to measure HC and CO emissions. This type of test is classified as a Basic I/M test by the EPA.

Figure 61–5 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. Continued

[object Object],Continued ,[object Object],[object Object],[object Object]

[object Object],[object Object],EXHAUST ANALYSIS AND COMBUSTION EFFICIENCY Continued Figure 61–6 A partial stream sampling exhaust probe being used to measure exhaust gases in parts per million (ppm) or percent (%).

[object Object],Continued ,[object Object],[object Object],[object Object],[object Object],[object Object],Acceptable levels of HC are 50 ppm or less. High levels of HC could be due to excessive oil consumption caused by weak piston rings or worn valve guides. The most common cause of excessive HC emissions is a fault in the ignition system. Items that should be checked include:

[object Object],What Does NMHC Mean?

[object Object],Continued ,[object Object],[object Object],[object Object],[object Object],CO levels of a properly operating engine should be less than 0.5%. High levels of CO can be caused by clogged or restricted crankcase ventilation devices such as the PCV valve, hose(s), and tubes. Other items that might cause excessive CO include

[object Object],Continued Oxygen The next gas is oxygen (O 2 ). There is about 21% oxygen in the atmosphere, and most of this oxygen should be “used up” during the combustion process to oxidize all the hydrogen and carbon (hydrocarbons) in the gasoline. Levels of O 2 should be very low (about 0.5%). High levels of O 2 , especially at idle, could be due to an exhaust system leak.

[object Object],See the chart on Page 738 of your textbook. NOTE: Adding 10% alcohol to gasoline provides additional oxygen to the fuel and results in lower CO and higher O 2 levels in the exhaust.

[object Object],How Can My Worn Out, Old, High Mileage Vehicle Pass an Exhaust Emissions test?

HC TOO HIGH ,[object Object],[object Object],[object Object],[object Object],[object Object],HINT: To make discussion easier in future reference, this list of ignition components and checks will be referred to simply as “spark stuff.”

CO TOO HIGH ,[object Object],[object Object],[object Object],[object Object],[object Object],HINT: One tech remembers “CO” as meaning “clogged oxygen” and always looks for restricted airflow into the engine whenever high CO levels are detected.

[object Object],MEASURING OXYGEN (O 2 ) AND CARBON DIOXIDE (CO 2 ) Continued NOTE: A hole in the exhaust system can draw outside air (oxygen) into the exhaust system. Therefore, to be assured of an accurate reading, carefully check the exhaust system for leaks. Using a smoke machine is an easy method to locate leaks in the exhaust system. Carbon dioxide (CO 2 ) is a measure of efficiency. The higher the level of CO 2 in the exhaust stream, the more efficiently the engine is operating. Levels of 12% to 17% are considered acceptable.

Figure 61–7 Exhaust emissions are very complex. When the air–fuel mixture becomes richer, some exhaust emissions are reduced, while others increase. Continued

[object Object],Find a Leak in the Exhaust System - Part 1 Figure 61–8 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.

[object Object],Find a Leak in the Exhaust System - Part 2 ,[object Object],[object Object],[object Object]

[object Object],Your Nose Knows - Part 1 ,[object Object],[object Object]

[object Object],Your Nose Knows - Part 2 ,[object Object],[object Object],[object Object],[object Object]

PHOTOCHEMICAL SMOG INFORMATION ,[object Object]

TESTING FOR OXIDES OF NITROGEN ,[object Object]

[object Object],Check For Dog Food?

[object Object],The Case of the Retarded Exhaust Camshaft - Part 1 ,[object Object],[object Object],[object Object],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).

[object Object],The Case of the Retarded Exhaust Camshaft - Part 2 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.

See the chart on Page 740 of your textbook.

[object Object],O 2 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 lower-than-normal pulse width indicates the computer is attempting to reduce fuel flow to the engine by decreasing the on-time for all injectors. The problem was a defective fuel-pressure 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.

SUMMARY ,[object Object],[object Object],[object Object],Continued

SUMMARY ,[object Object],[object Object],[object Object],( cont. )

Chapter 61

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Chapter 61