OBJECTIVES After studying Chapter 23 the reader will

OBJECTIVES After studying Chapter 23, the reader will be able to: 1. Prepare for the ASE Engine Performance (A 8) certification test content area “D” (Emission Control Systems). 2. Describe the purpose and function of the positive crankcase ventilation and the air-injection reaction system. 3. Discuss how the PCV and SAI systems are tested under OBD-II regulations. 4. Explain methods for diagnosing and testing faults in the PCV and SAI systems. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

BACKGROUND • The process of combustion produces power in an internalcombustion engine. • Under perfect conditions, combustion would completely consume the air-fuel mixture, leaving only harmless byproducts, such as water vapor (H 2 O) and carbon dioxide (CO 2). • Combustion of the air-fuel mixture is never perfect, however, and at best is incomplete. • By-products other than H 2 O and CO 2 remain after the combustion process and go out the tailpipe. • These by-products of incomplete combustion include carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NOX). Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CRANKCASE VENTILATION • The problem of crankcase ventilation has existed since the beginning of the automobile because no piston ring, new or old, can provide a perfect seal between the piston and the cylinder wall. • Positive crankcase ventilation (PCV) systems were developed to ventilate the crankcase an recirculate the vapors to the engine’s induction system so they can be burned in the cylinders. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CRANKCASE VENTILATION Closed PCV Systems FIGURE 23 -1 A PCV system includes a hose from the air cleaner assembly so that filtered air can be drawn into the crankcase. This filtered air is then drawn by engine vacuum through the PCV valve and into the intake manifold where the crankcase fumes are burned in the cylinder. The PCV valve controls and limits this flow of air and fumes into the engine and the valve closes in the event of a backfire to prevent flames from entering the crankcase area. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CRANKCASE VENTILATION Closed PCV Systems FIGURE 23 -2 A dirty PCV vent filter inside the air cleaner housing. The air enters the crankcase through this filter and then is drawn into the engine through the PCV valve. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PCV VALVES • The PCV valve in most systems is a one-way valve containing a springoperated plunger that controls valve flow rate. FIGURE 23 -3 Spring force, crankcase pressure, and intake manifold vacuum work together to regulate the flow rate through the PCV valve. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PCV VALVES FIGURE 23 -4 Air flows through the PCV valve during idle, cruising, and lightload conditions. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PCV VALVES FIGURE 23 -5 Air flows through the PCV valve during acceleration and when the engine is under a heavy load. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PCV VALVES FIGURE 23 -6 PCV valve operation in the event of a backfire. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ORIFICE-CONTROLLED SYSTEMS • While most orifice flow control systems work the same as a PCV valve system, they may not use fresh air scavenging of the crankcase. • Crankcase vapors are drawn into the intake manifold in calibrated amounts depending on manifold pressure and the orifice size. • If vapor availability is low, as during idle, air is drawn in with the vapors. • During off-idle operation, excess vapors are sent to the air cleaner; as crankcase pressure increases oil, the gases backup. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM DIAGNOSIS • When intake air flows freely, the PCV system functions properly, as long as the PCV valve or orifice is not clogged. • Modern engine design includes the air and vapor flow as a calibrated part of the air-fuel mixture. FIGURE 23 -7 A visual inspection found this deteriorated PCV vacuum hose. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM DIAGNOSIS • PCV System Performance Check – A properly operating positive crankcase ventilation system should be able to draw vapors from the crankcase and into the intake manifold. – If the pipes, hoses, and PCV valve itself are not restricted, vacuum is applied to the crankcase. – A slight vacuum is created in the crankcase (usually less than 1 in. Hg if measured at the dipstick) and is also applied to other areas of the engine. • There are several methods that can be used to test a PCV system. – – The Rattle Test The 3 x 5 Card Test The Snap-Back Test Crankcase Vacuum Test Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM DIAGNOSIS FIGURE 23 -8 A typical PCV valve. A defective or clogged PCV valve or hose can cause a rough idle or stalling problem. Because the air flow through the PCV valve accounts for about 20% of the air needed by the engine at idle, use of the incorrect valve for an application could have a severe effect on idle quality. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM DIAGNOSIS FIGURE 23 -9 A typical PCV valve installed in a rubber grommet in the valve cover. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM DIAGNOSIS FIGURE 23 -10 A water manometer being used to check for a slight vacuum when testing at the oil dipstick tube. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PCV MONITOR • All vehicles must be checked for properation of the PCV system starting with 2004 and newer vehicles. • The PCV monitor will fail if the PCM detects an opening between the crankcase and the PCV valve or between the PCV valve and the intake manifold Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PCV-RELATED DIAGNOSTIC TROUBLE CODE Advanced Engine Performance Diagnosis, 4/e By James D. Halderman ©

SECONDARY AIR INJECTION (SAI) SYSTEM • An air pump provides the air necessary for the oxidizing process inside the catalytic converter. FIGURE 23 -11 A typical belt-driven air pump. Air enters through the revolving fins. These fins act as a moving air filter because dirt is heavier than air and therefore the dirt in the air is deflected off the fins at the same time the air is drawn into the pump. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

SECONDARY AIR INJECTION (SAI) SYSTEM Air Switching Valves FIGURE 23 -12 (a) When the engine is cold and before the oxygen sensor is hot enough to reach closed loop, the air flow is directed to the exhaust manifold(s) through one-way check valve(s). These valves keep exhaust gases from entering the switching solenoids and the air pump itself. (b) When the engine achieves closed loop, the air flows from the pump, is directed to the catalytic converter, and then moves through a check valve. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

AIR DISTRIBUTION MANIFOLDS AND NOZZLES • Air is delivered to the exhaust system in one of two ways: – An external air manifold, or manifolds, distributes the air through injection tubes with stainless steel nozzles. The nozzles are threaded into the cylinder heads or exhaust manifolds close to each exhaust valve. – An internal air manifold distributes the air to the exhaust ports near each exhaust valve through passages cast in the cylinder head or the exhaust manifold. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

AIR DISTRIBUTION MANIFOLDS AND NOZZLES • Three basic types of air pumps are the belt-driven air pump, the pulse air-driven air pump, and the electric motor-driven air pump. – – Exhaust Check Valves Belt-Driven Air Pumps Electric Motor-Driven Air Pumps Pulse Air-Driven Devices Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

AIR DISTRIBUTION MANIFOLDS AND NOZZLES FIGURE 23 -13 An AIR exhaust check valve between the rubber air hose and the metal discharge tubes. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

AIR DISTRIBUTION MANIFOLDS AND NOZZLES FIGURE 23 -14 Exhaust check valves in the AIR system allow air to flow in only one direction. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

AIR DISTRIBUTION MANIFOLDS AND NOZZLES FIGURE 23 -15 A typical belt-driven air pump used on an older model Chevrolet Corvette. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

AIR DISTRIBUTION MANIFOLDS AND NOZZLES FIGURE 23 -16 The air pump supplies air to the exhaust port of each cylinder. Unburned HCs are oxidized into CO 2 and H 2 O and CO is converted to CO 2. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

AIR DISTRIBUTION MANIFOLDS AND NOZZLES FIGURE 23 -17 A typical electric motor-driven secondary air injection (SAI) pump. This unit is on a Chevrolet Corvette and only works when the engine is cold. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

SECONDARY AIR INJECTION SYSTEM DIAGNOSIS • The secondary air injection system should be inspected if an exhaust emissions test failure occurs. • With the engine running, check for normal operation: – Visual Inspection – Four-Gas Exhaust Analysis Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

SAI-RELATED DIAGNOSTIC TROUBLE CODE Advanced Engine Performance Diagnosis, 4/e By James D. Halderman ©

SUMMARY 1. Positive crankcase ventilation (PCV) systems use a valve or a fixed orifice to control the fumes from the crankcase back into the intake system. 2. A PCV valve regulates the flow of fumes depending on engine vacuum and seals the crankcase vent in the event of a backfire. 3. As much as 30% of the air needed by the engine at idle speed flows through the PCV system. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

SUMMARY 4. PCV tests include the rattle test, card test, snapback test, and crankcase vacuum test. 5. The SAI system forces air at low pressure into the exhaust to reduce CO and HC exhaust emissions. 6. Exhaust check valves are used between the AIR pump and the exhaust manifold to prevent exhaust gases from flowing into, and causing damage to, the AIR pump and valves. Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

REVIEW QUESTIONS 1. What exhaust emissions do the PCV valve and SAI system control? 2. How does a PCV valve work? 3. What does the abbreviation PCV mean? 4. What does the abbreviation AIR mean? Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 1. The PCV system controls which exhaust emission(s)? a) b) c) d) HC CO NOX Both HC and CO Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 2. How much of the air needed by the engine flows through the PCV system when the engine is at idle speed? a) b) c) d) 1% to 3% 5% to 10% to 20% Up to 30% Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 3. Technician A says that if the PCV system were defective or clogged, the engine could idle rough. Technician B says that the engine may stall. Which technician is correct? a) b) c) d) Technician A only Technician B only Both Technicians A and B Neither Technician A nor B Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 4. Technician A says that if a PCV valve rattles, then it is okay and does not need to be replaced. Technician B says that if a PCV valve does not rattle, it should be replaced. Which technician is correct? a) b) c) d) Technician A only Technician B only Both Technicians A and B Neither Technician A nor B Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 5. Technician A says that the PCV system should create a slight pressure in the crankcase at idle. Technician B says that the PCV system should create a slight vacuum in the crankcase at 2500 RPM. Which technician is correct? a) b) c) d) Technician A only Technician B only Both Technicians A and B Neither Technician A nor B Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 6. The SAI system is used to reduce which exhaust emission(s)? a) b) c) d) HC CO NOX Both HC and CO Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 7. Two technicians are discussing exhaust check valves used in SAI systems. Technician A says that they are used to prevent the output from the AIR pump from entering the intake manifold. Technician B says the check valves are used to keep the exhaust from entering the AIR pump. Which technician is correct? a) b) c) d) Technician A only Technician B only Both Technicians A and B Neither Technician A nor B Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 8. Where is the output of the AIR pump directed when the engine is cold? a) b) c) d) Exhaust manifold Catalytic converter Air cleaner assembly To the atmosphere Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 9. The switching valves on the AIR pump have failed several times. Technician A says that a defective exhaust check valve could be the cause. Technician B says that a restricted exhaust system could be the cause. Which technician is correct? a) b) c) d) Technician A only Technician B only Both Technicians A and B Neither Technician A nor B Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CHAPTER QUIZ 10. When checking for the properation of the SAI system using an exhaust gas analyzer, how much should the oxygen (O 2) levels increase when the pump is allowed to function? a) b) c) d) 1% to 4% 5% to 10% to 20% Up to 30% Advanced Engine Performance Diagnosis, 4/e By James D. Halderman © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458