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AVI ASE-A8 Manual

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PERFORMANCE
Disclaimer of Warranties:
This manual contains test procedures and test information obtained by an ASE Master Technician with known
good test equipment on real vehicles. Your tests may vary due to your test equipment or procedures. No warranty
can be made from the ideas presented due to personal testing procedures, nor does the author or anyone
connected with him or her assume any responsibilities or liabilities. The use of this manual is conditional on the
acceptance of this disclaimer. If the terms of this disclaimer are not acceptable, please return this manual.
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50902
ASE-A8
ENGINE
Automotive Video 6280 Arc Way
Ft. Myers, FL 33966
1-800-71-TRAIN (1-800-718-7246)
www.auto-video.com
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  • Page 1 ASE-A8 ENGINE PERFORMANCE Disclaimer of Warranties: This manual contains test procedures and test information obtained by an ASE Master Technician with known good test equipment on real vehicles. Your tests may vary due to your test equipment or procedures. No warranty can be made from the ideas presented due to personal testing procedures, nor does the author or anyone connected with him or her assume any responsibilities or liabilities.

  • Page 3: Table Of Contents

    ENGINE PERFORMANCE FOR ASE TEST A8 Contents ASE A8 Task List ........ii hapter A: General Diagnosis.
  • Page 4 ASE A8 TEST PREP TASK LIST Content Area Questions in Test Percentage of Test A. General Diagnosis B. Ignition System Diagnosis and Repair C. Fuel, Air Induction and Exhaust Systems Diagnosis and Repair D. Emissions Control Systems Diagnosis and Repair (Including OBD II) 1.
  • Page 5 ASE A8 TEST PREP TASK LIST B. Ignition System Diagnosis and Repair (8 questions) 1. Diagnose ignition system related problems such as no-starting, hard starting, engine misfire, poor driveability, spark knock, power loss, poor mileage, and emissions problems; determine root cause; determine needed repairs.
  • Page 6 ASE A8 TEST PREP TASK LIST 3. Inspect, test, service, and replace components of the EGR system, including EGR valve, tubing, passages, vacuum/pressure controls, filters, hoses, electrical/electronic sensors, controls, solenoids and wiring of exhaust gas recirculation (EGR) systems. 3. Secondary Air Injection (AIR) And Catalytic Converter (2 questions) 1.

  • Page 7: Hapter A: General Diagnosis

    Chapter A GENERAL DIAGNOSIS Poor engine performance can be the result of a long list make sure the engine is in sound mechanical condition. of problems. Performance, or driveability problems may In addition to internal engine defects, driveability prob- be indicated by customer complaints of no starting, lems may be caused by a malfunction in the electrical, hard starting, loss of power, poor fuel mileage, engine fuel, ignition, or emission control systems.
  • Page 8 Chapter A: General Diagnosis ROAD TEST • Fuel lines, hoses, and fittings that are free of leak- age and damage Whenever possible, let the customer accompany you on • Battery, cables, and connections that are tight and the road test. The customer knows the vehicle and can free of corrosion.
  • Page 9 Chapter A: General Diagnosis Technical Service Bulletin SUBJECT: Sags/Hesitation/Stumble/Start & Stall OVERVIEW: This bulletin involves selectively erasing and reprogramming the Powertrain Control Module (PCM) with new software (calibration changes). MODELS: 2003 Minivan and Truck NOTE: THIS INFORMATION APPLIES TO VEHICLES EQUIPPED WITH A 3.34L ENGINE. SYMPTOM/CONDITION: Sags/Hesitation/Stumble or Start &...
  • Page 10 Chapter A: General Diagnosis Fuel and EVAP Pipe Caution These manuals are more in-depth than Service Manuals as they provide component descriptions and operation In order to reduce the risk of fire and personal injuryob- theory along with the applicable troubleshooting proce- serve the following items: dures.
  • Page 11 Chapter A: General Diagnosis Avoid the following actions unless required by the diag- because these parts operate at one-half crankshaft nostic procedure: speed. • Jumpering or grounding of the components or con- A stethoscope is a handy tool for isolating noises. You nectors can also use a timing light to determine whether a noise •...
  • Page 12 Chapter A: General Diagnosis Keep in mind that oil vapor odors are not always the re- ioning of the extra gas pressure pushing on the pis- sult of an internal engine problem. A clogged or mal- functioning positive crankcase ventilation (PCV) system •...
  • Page 13 Chapter A: General Diagnosis Fig. 1-2. Typical engine analyzer power balance panel. Cylinder Power Balance Test Fig. 1-3. Compression tester gauge installed in the spark plug hole. The Powertrain Control Module (PCM) in most latemod- el vehicles incorporates the ability to conduct a power and the spark plug.
  • Page 14 Chapter A: General Diagnosis Cylinder Leakage Test A cylinder leakage tester, or leak-down tester, gives more detailed results than a compression test. Used as a follow-up to compression testing, a leakage test can reveal: • The exact location of a compression leak •...
  • Page 15 Chapter A: General Diagnosis FIRING INTERMEDIATE DWELL SECTION SECTION SECTION 8 CYL 6 CYL 4 CYL ALL CYLINDERS Fig. 1-6. Cylinder traces are displayed one after another in a parade pattern. Fig. 1-5. All cylinder traces are displayed one on top of another in a superimposed pattern.
  • Page 16 Chapter A: General Diagnosis SPARK BEGINS INTERMEDIATE SECTION FIRING SECTION SPARK ENDS SPARK ENDS PRIMARY CIRCUIT SWITCHES ON DIMINISHING OSCILLATIONS FIRING LINE Fig. 1-8. A normal primary circuit firing trace. Fig. 1-9. The intermediate section begins as the spark extinguishes and continues until the primary circuit is switched on.
  • Page 17 Chapter A: General Diagnosis Fig. 1-11. The onboard diagnostic system, which monitors sensor and actuator signals, records a DTC when a circuit abnormality occurs. Fuel System Diagnosis lems, refer to Ignition System Diagnosis discussed pre- viously. Fuel system malfunctions can cause an assortment of driveability problems, such as engine surging, stalling Electrical System Diagnosis and misfiring, hard or no starting, and poor fuel mileage.
  • Page 18 Chapter A: General Diagnosis signal that is outside its limits, it records a diagnostic trouble code (DTC) in its memory. Generally, the computer is capable of recognizing the following: •A particular signal, such as engine speed, is not being furnished •...
  • Page 19 Chapter A: General Diagnosis Fig. 1-13. Typical breakout box. Fig. 1-14. Typical exhaust gas analyzer. are available in many styles and designs. Current mod- system from supplying oxygen into the exhaust stream. els are designed to sample and analyze either four or five This decreases the amount of O2 at the tailpipe, and gasses present in the exhaust from the vehicle.
  • Page 20 Chapter A: General Diagnosis AIR-FUEL POSSIBLE CAUSES RELATED CRUISE EMISSION IDLE RATIO SYMPTOMS IDLE 1800-2000 Rich AFR Vacuum leak to map Black smoke or Below sensor sulfur odor 10:1 Fuel injectors leaking Engine in open loop 300 ppm Bad Power Valve Surge/hesitation (carburetor) Engine not...
  • Page 21 Chapter A: General Diagnosis Condition Ignition Misfire Large Some Some Some to Large Some Increase Decrease Decrease Decrease Decrease Compression Some to Large Some Some Some Some Loss Increase Decrease Decrease Decrease Increase Rich Mixture Some to Large Large Some Some Large Increase...
  • Page 22 Chapter A: General Diagnosis Abnormal CO2 and O2 Readings Since the catalytic converter reduces HC and CO, these emissions are unreliable for determining the airfuel ratio. However, CO2 and O2 readings can be useful, provid- ed that the air injection system has been disabled. When air and fuel entering the engine burns with the least amount of wasted energy, at the stoichiometric air- fuel ratio, the engine emits the highest amount of CO2.
  • Page 23 Chapter A: General Diagnosis Adjustment Methods Follow this procedure: 1. Starting with any valve, back off the rocker arm Typical valve clearance specifications range from 0.004 locknut until the valve starts to clatter. At this point, to 0.025 inch (0.10 to 0.64 mm) for intake valves and the valve has too much clearance.
  • Page 24 Chapter A: General Diagnosis ADJUSTING SCREW ROCKER LOCKNUT ROCKER SHAFT VALVE CAMSHAFT SPRING INTAKE VALVE EXHAUST VALVE Fig. 1-19. Overhead cam engine with rocker arms and screw-type adjusters. 1. Position a cylinder at TDC on its power stroke so both valves are closed. 2.
  • Page 25 Chapter A: General Diagnosis CYLINDER HEAD TIMING MARK SPROCKET TIMING MARK CAMSHAFT SPROCKET SPECIAL ADJUSTING MAGNET TOOL SHIM ENGINE CASE Fig. 1-20. Depress the follower with the special tool to remove/install TIMING MARK the adjuster shim. 1. Position the cylinder to be checked at TDC. 2.
  • Page 26 Chapter A: General Diagnosis Check the coolant level and test the concentration using a hydrometer. Look for signs of oil and combustion con- tamination. Engine oil escaping into the coolant will not mix. The oil will float on top of the coolant. Combustion gases will chemically react with coolant to rapidly break it down turning it a rust-brown color.
  • Page 27 Chapter A: General Diagnosis Fig. 1-23. Testing engine coolant with a hydrometer. System Pressure Test Pressure testing the cooling system is a quick and easy way to find an external leak. Perform the test on a cold engine using a hand pump with a gauge: Fig.
  • Page 28 Chapter A: General Diagnosis FAN SHROUD CROSSFLOW RADIATOR Splice Ground Incomplete Connector Component RADIATOR View FAN SWITCH AUTOMATIC TRANSMISSION OIL COOLER FITTINGS ELECTRIC FAN BLADES FAN MOTOR Switch Complete Battery Motor Component View Fig. 1-25. Typical electric cooling fan assembly. Fig.
  • Page 29 Chapter A: General Diagnosis Fig. 1-27. Typical automotive electrical schematic. The table consists of four columns labeled as follows: Locator View • Name This column contains the reference to the appropriate • Location locator view. • Locator View Circuit Descriptions •...
  • Page 30 Chapter A: General Diagnosis Fig. 1-28. Typical component locator chart. How to Use Connector End Views today only on the minority of batteries that are unsealed and have removable filler caps. Connector end views show the cavity or terminal loca- tions for all the most connectors shown in the system Some sealed maintenance-free batteries are equipped schematic(s).
  • Page 31 Chapter A: General Diagnosis Fig. 1-29. Typical connector end view chart. ABNORMAL OR PHANTOM BATTERY • An accessory, such as a trunk light, glove box light, DRAIN PROBLEMS underhood light, or cigarette lighter, remaining on when the vehicle is not in use Phantom battery drain, or parasitic draw, is caused by •Parasitic drains required to operate systems that something in the vehicle constantly drawing current...
  • Page 32 Chapter A: General Diagnosis Fig. 1-30. Maintenance-free battery state-of-charge indicator. Due to the higher parasitic current drains on late model vehicles, the old test of removing a battery cable con- Fig. 1-31. Connection for testing for parasitic draw. nection and tapping it against the terminal while looking for a spark is both dangerous and no longer a valid check for excessive current drain.
  • Page 33 Chapter A: General Diagnosis High resistance in the cranking circuit can cause either high or low current draw. This is because the starter VOLTMETER AMMETER motor requires high current to get up to speed. Once up to speed, the starter motor acts like a generator to pro- duce a counter voltage which limits the current.
  • Page 34 Chapter A: General Diagnosis VOLTMETER STARTER REMOTE RELAY STARTER VHz~ IGNITION SWITCH IGNITION VHz~ SWITCH SWITCH SOLENOID NEUTRAL SAFETY SWITCH STARTER BATTERY TESTER MOTOR CHASSIS/ BODY AMPS ENGINE STARTER BATTERY Fig. 1-33 Typical voltmeter connections for performing a starter Fig. 1-34. Connections for loading the system and testing for voltage motor cranking voltage test.
  • Page 35 Chapter A: General Diagnosis BATTERY VHz~ IGNITION SWITCH SWITCH INDICATOR LAMP BAT. SOLENOID DIODE TRIO STARTER BATTERY TESTER MOTOR CHASSIS/ BODY AMPS ENGINE REGULATOR Fig. 1-35 Connections for loading the system and testing for voltage drop on the ground side of the starting system. 1.
  • Page 36 Chapter A: General Diagnosis shorted to power in a system with an internally 5. Adjust the carbon pile to obtain the maximum am- grounded field, or B-circuit meter reading while keeping the system voltage • High resistance in the wiring between the battery above 12 volts.
  • Page 37 Chapter A: General Diagnosis VHz~ VHz~ BATTERY BATTERY BATTERY BATTERY TESTER TESTER AMPS AMPS GENERATOR GENERATOR Fig. 1-37. Equipment connections for checking voltage drop in the Fig. 1-38. Equipment connections for checking voltage drop in the insulated, or positive, generator circuit. ground, or negative, generator circuit.
  • Page 38 Chapter A: General Diagnosis Field Current Draw Test To begin: 1. Check the battery electrolyte level, state-of charge, The field current draw test is performed with the engine and capacity. If the battery is worn out or defective, off. For some vehicles, the regulator or warning lamp cir- the charging system may not be at fault.
  • Page 39 Chapter A: Review Questions 1. The first step in diagnosing a 5. What would be the sealing 9. What would be the approximate performance or driveability ability of a cylinder with a 28 state-of-charge of a battery problem is to: percent loss of air pressure whose temperature-corrected during a leakage test?

  • Page 40: Chapter B: Ignition System Diagnosis And Repair

    Chapter B IGNITION SYSTEM DIAGNOSIS AND REPAIR This chapter discusses testing, repairing, and replacing points could not handle the required increase in current individual components of the ignition system. Most flow. To solve this problem the first electronic ignition modern ignition systems contain delicate, and expen- systems replaced breaker points with a transistor.
  • Page 41 Chapter B: Ignition System Diagnosis and Repair Symptom Definition Possible Causes NO START WI TH NORMAL The starter cranks the engine Primary ignition circuit CRANK SPEED normally but the engine does failure not start. No RPM signal to ECM / Ignition Module Wet secondary ignition system components...
  • Page 42 Chapter B: Ignition System Diagnosis and Repair Sources of high primary resistance include: • Loose, corroded, or damaged wiring connections • An incorrect or defective coil •A poor ground at the ignition module Low source voltage can be caused by the following: •...
  • Page 43 Chapter B: Ignition System Diagnosis and Repair Fig. 2-4. Some systems use an additional sensor on the camshaft to properly phase the firing sequence. Fig. 2-3. A crankshaft position sensor provides the input used to initiate plug firing on a direct ignition system. For any ignition system to operate properly, the follow- ing conditions must be met: •...
  • Page 44 Chapter B: Ignition System Diagnosis and Repair LONG, LOW SPARKLINE AND SHORT OSCILLATIONS SEPARATED FROM OTHERS SHOWS LOW RESISTANCE LACK OF SPARKLINE SHOWS OPEN PLUG CABLE Fig. 2-7. A low, long sparkline on a secondary superimposed pattern indicates low-resistance in one cylinder. Fig.
  • Page 45 Chapter B: Ignition System Diagnosis and Repair HIGH, SHORT SPARKLINE DWELL AT 800 RPM DWELL AT 1700 RPM Fig. 2-10. A high, short sparkline on a secondary superimposed pattern indicates high-resistance in one cylinder. Intermediate Section Abnormalities DWELL AT Use the intermediate section of the trace to check coil 3000 RPM function.
  • Page 46 Chapter B: Ignition System Diagnosis and Repair light brownish-white accumulations that form on and SPECIAL TOOL around the electrode. Normally, ash deposits are non- conductive, but large amounts may cause misfiring. Splash Fouling SPARK PLUG WIRE AND Small dark patches visible on the insulator indicate BOOT splash fouling.
  • Page 47 Chapter B: Ignition System Diagnosis and Repair SPECIAL BENDING TOOL SIDE ELECTRODE CENTER ELECTRODE ROUND WIRE FEELER GAUGE Fig. 2-14. Adjusting spark plug electrode gap. •Do not assume that new plugs are correctly gapped • Do not make gap adjustments by tapping the elec- trode on a workbench or other solid object Cleaning the threaded plug holes in the cylinder head with a thread chaser will ensure easy spark plug instal-...
  • Page 48 Chapter B: Ignition System Diagnosis and Repair Ignition Cable Service Excessive resistance in the secondary circuit can cause OHMMETER driveability problems such as an engine misfire, higher burn voltage, and shorter burn time. Damaged cables are often the cause, and can be tested with an ohmme- VHz~ ter.
  • Page 49 Chapter B: Ignition System Diagnosis and Repair Fig. 2-17. Typical coil-near-plug ignition coil installation. Manufacturers provide voltage drop specifications for various ignition components. Measure the voltage drop across the ignition module ground as follows: Fig. 2-16. Typical multiple coil coil-pack. 1.
  • Page 50 Chapter B: Ignition System Diagnosis and Repair VHz~ VHz~ DISTRIBUTOR BATTERY COIL IGNITION SWITCH Fig. 2-18. Checking secondary coil winding resistance with an Fig. 2-19. Checking ignition coil current draw with an ammeter. ohmmeter. There are several advantages of multiple ignition coil 1.
  • Page 51 Chapter B: Ignition System Diagnosis and Repair ammeter to the positive (battery) coil terminal, figure 2- 19. When using an inductive ammeter, fit the inductive pickup over the primary wire to the coil positive terminal FIRING INTERMEDIATE DWELL leaving the wire connected. SECTION SECTION SECTION...
  • Page 52 Chapter B: Ignition System Diagnosis and Repair CAMSHAFT ONE CAMSHAFT REVOLUTION (720 OF CRANKSHAFT ROTATION) TIMING ROTOR TOOTH CAMSHAFT POSITION (CMP) SENSOR SIGNAL SIGNAL CRANKSHAFT POSITION (CKP) SENSOR 30 GAP (MISSING TEETH) ONE CRANKSHAFT REVOLUTION (360 ) MISSING TEETH TIMING ROTOR Fig.
  • Page 53 Chapter B: Ignition System Diagnosis and Repair INPUT VANE VOLTAGE HIGH SIGNAL MAGNET SHUTTER BLADE VOLTAGE HALL POWER INPUT ELEMENT STRONG SIGNAL MAGNETIC ROTATING FIELD SHAFT GROUND PERMANENT INPUT HALL MAGNET ELEMENT VOLTAGE SWITCHING TRANSISTOR VANE SHUTTER Fig. 2-23. Distributor-mounted Hall-effect sensor. SIGNAL WHEEL VOLTAGE...
  • Page 54 Chapter B: Ignition System Diagnosis and Repair WINDOW HIGH SIGNAL VOLTAGE PHOTO TRANSISTOR Fig. 2-25. Square-wave pattern from a Hall-effect sensor. When a slot in the trigger wheel is aligned with the sensor the signal is low because the magnetic filed is not engulfing the Hall element.
  • Page 55 Chapter B: Ignition System Diagnosis and Repair Fig. 2-27. The sample vehicle wiring diagram shows PCM sensors, actuator, and related circuits.
  • Page 56 Chapter B: Ignition System Diagnosis and Repair Fig. 2-28. Sample vehicle electrical symbols. Internal PCM functions tions and adapt output commands to the "learned" characteristics of vehicle operation. This feature, Battery, or system, voltage is supplied to the PCM at known as adaptive strategy, allows the system to two points, pins 12 and 13.
  • Page 57 Chapter B: Ignition System Diagnosis and Repair Because the PCM operates on low voltage signals, even small changes in resistance anywhere along a circuit can effect system performance. Many driveability com- plaints and control system malfunctions are a direct re- sult of excessive resistance on the monitored circuits.
  • Page 58 Chapter B: Review Questions 1. Low primary circuit voltagcan be 4. Spark plug overheating, which is 7. When using an ohmmeter to caused by all of the fo lowing indicated by a clean, white check an ignition coil, there should EXCEPT: insulator tip and excessive be infinite resistance between:...

  • Page 59: Diagnosis And Repair

    Chapter C FUEL, AIR INDUCTION, AND EXHAUST SYSTEMS DIAGNOSIS AND REPAIR 1. Inspect the fuel tank for: To run efficiently, an engine must be supplied with a constant flow of clean pressurized fuel and filtered air in • Physical damage and leakage at fittings, con- precisely metered amounts.
  • Page 60 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair HARD START COLD ENGINE LACK OF POWER/SLUGGISH POOR FUEL ECONOMY SECONDARY IGNITION SYSTEM SECONDARY IGNITION SYSTEM SECONDARY IGNITION SYSTEM FUEL PRESSURE ECM POWER AND GND CKT ECM POWER AND GND CKT THROTTLE POSITION SENSOR FUEL PRESSURE ENGING VACUUM...
  • Page 61 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair Replacement O-rings must be specifically designed for fuel system use. Tighten fittings to the specified torque- value to prevent O-ring damage. FLARE NUT FITTING Fuel Filter Replacement The fuel filter is the only item of the system that must be TUBING changed at regular service intervals.
  • Page 62 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair VAPOR BYPASS NIPPLE FUEL OUTLET FUEL INLET DIRECTION OF FUEL FLOW Fig. 3-3. Inline fuel filter with a vapor bypass fitting. Fig. 3-4. Cut-away of a typical high-pressure fuel injection filter. Replacing Fuel Injection System Filters Fuel system pressure must be relieved to change the- filter on a fuel injected engine.
  • Page 63 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair VACUUM-PRESSURE GAUGE IDLE PRESSURE GAUGE TACHOMETER (ENGINE SPEED) 6 INCH MAXIMUM FUEL LINE FROM FUEL PUMP FUEL PUMP CARBURETOR OR THROTTLE BODY CARBURETOR THROTTLE BODY Fig. 3-6. Direct gauge connection for performing a mechanical fuel pump pressure test.
  • Page 64 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair PRESSURE DISCONNECTED GAUGE VACUUM HOSE PRESSURE RELEASE BUTTON VACUUM FUEL PRESSURE PUMP REGULATOR SCHRADER VALVE FUEL DRAIN FITTING TUBE Fig. 3-9. Fuel pressure gauge with relief value for servicing Schrader valve-equipped fuel injection systems.
  • Page 65 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair Low residual pressure can be caused by leaking fuel lines, injectors, or cold start valve, a faulty fuel pump check valve, or a defective pressure regulator. Fuel Injection Volume Test When a pump volume measure is specified, the sample is taken at the fuel return line rather than at the delivery pipe.
  • Page 66 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair Fig. 3-11. Fuel pressure regulator operation. External Electric Pump Vacuum acting on the top side of the diaphragm along with spring pressure controls fuel pressure. A decrease Older fuel injected vehicles use an external electric fuel in vacuum creates an increase in fuel pressure.
  • Page 67 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair INTERNAL FUEL FLOW TO FUEL FUEL FILTER INJECTORS RUBBER FUEL FILTER/ GROMMET FUEL AT PUMP PRESSURE MODULE REGULATOR CALIBRATED SPRINGS EXCESS FUEL BACK TO TANK FUEL INLET Fig. 3-12. Typical in-tank fuel pressure regulator. lization.
  • Page 68 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair OHMMETER OHMMETER OHMMETER VHz~ VHz~ VHz~ DETACHED CONNECTOR DETACHED POWER CONNECTOR OR VREF CIRCUIT VREF SIGNAL SIGNAL SIGNAL RETURN GROUND HARNESS SENSOR HARNESS SENSOR Fig. 3-14. Checking the resistance of a thermistor sensor with an ohmmeter.
  • Page 69 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair HOLD Hz FREQUENCY OXYGEN SENSOR ELEMENT 5.28 PEAK-PEAK ATMOSPHERE ATMOSPHERE 50.0 DUTY CYCLE OXYGEN OXYGEN 5.00 PULSE WIDTH GENERATED SIGNAL 0.6 v 0.3 v EXHAUST EXHAUST GENERATED SIGNAL OXYGEN OXYGEN MORE LESS...
  • Page 70 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair VOLTAGE READINGS COURSE OF ACTION Minimum Maximum Average None - System operating Under 200 mV Over 700 mV 400-500 mV properly. Over 200 mV 400-500 mV Not applicable Replace oxygen sensor. Replace oxygen sensor.
  • Page 71 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair HOLD mV MAXIMUM 0.00 MINIMUM 1200mV 1000 200ms/DIV RECALL BACK SEARCH PRINT SELECT Fig. 3-21. Typical fuel injector. Fig. 3-20. Oscilloscope trace of a good HO S that is switching •...
  • Page 72 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair COMBINATION PUMP FUEL AND TANK CAP INJECTOR FIRST 0-60 P.S.I. 30 P.S.I. TESTER READING PRESSURE GAUGE PRESSURE RELIEF VALVE (INITIAL PRESSURE) GAUGE CHECK VALVE FUEL SECOND INJECTOR READING CLEANER (PRESSURE FILTER AFTER...
  • Page 73 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair THROTTLE BODY FUEL INJECTION FUEL PRESSURE REGULATOR Throttle body, or single point, fuel injection is a common INJECTOR FUEL feature on many domestic engines. The throttle body SUPPLY FROM TANK assembly houses the throttle plates and provides the INTAKE mounting point for the fuel injectors, idle speed con-...
  • Page 74 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair INTAKE AIR THROTTLE BODY AIR PREHEAT CONTROL VALVE AIR OUTLET (VACUUM MOTOR) TUBE FRESH INLET VANE AIRFLOW METER HOT AIR INLET TUBE AIR CLEANER AIR FILTER HOUSING Fig. 3-25. The intake ductwork delivers fresh air to the combustion chambers. Most TBI engines react differently than carbureted en- Exhaust Manifold Service gines because they use a speed density method of fuel...
  • Page 75 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair Fig. 3-26. Typical exhaust system components. Catalytic Converter Service Temperature Test Before testing, repair any known problems that may Catalytic converters are required by law to give at least cause high emissions, as well as any exhaust leaks.
  • Page 76 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair LACK OF POWER OR HIGH OIL CONSUMPTION EMITS BLACK EXHAUST SMOKE OR EMITS BLUE EXHAUST SMOKE POSSIBLE CAUSE CORRECTION POSSIBLE CAUSE CORRECTION Damaged or disconnected Inspect and correct Excessive blowby or PCV Check for engine wear;...
  • Page 77 Chapter C: Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair BEARING INLET WASTEGATE BOOST HOSE ACTUATOR PISTON CARBON BRACKET ACTUATOR BEARING RING FACE SEAL SEAL PASSAGE OUTLET Fig. 3-31. Typical turbocharger wastegate actuator installation. Fig. 3-30. Check turbocharger shaft seals for signs of oil leakage. the system from overcharging, figure 3-31.
  • Page 78 Chapter C: Review Questions 4. Which of the following is the typical 7. The signal carried by the ground 1. All of the following may be used fuel line EXCEPT: operating pressure range of a wire on a potentiometer is also throttle body injection system? known as: a.

  • Page 79: Chapter D: Emission Control Systems Diagnosis And Repair

    Chapter D EMISSION CONTROL SYSTEMS DIAGNOSIS AND REPAIR Reducing the exhaust emissions of a modern internal- combustion engine to an acceptable legal level is a com- THIS END OF THE PCV THIS END IS SUBJECT VALVE IS SUBJECT TO TO INTAKE MANIFOLD plex task.
  • Page 80 Chapter D: Emission Control Systems Diagnosis and Repair 3. Listen for a hissing noise from the valve. 4. Place a finger over the end of valve. A strong vacu- um should be felt and engine speed should drop by 40 RPM or more if the system is working properly. AIR CLEANER COVER If engine speed does not increase when the valve is dis-...
  • Page 81 Chapter D: Emission Control Systems Diagnosis and Repair Fig. 4-3. Typical 3-port vacuum switch test procedure. ate the pintle and control the flow of exhaust gasses, fig- a steady reading after vacuum is applied. Note the time ure 4-6. If the EGR valve fails to open when it should, ex- required for the vacuum gauge to level off to a steady pect: reading and compare it to specifications.
  • Page 82 Chapter D: Emission Control Systems Diagnosis and Repair the fasteners to the specified torque value to prevent ex- haust gas leaks. TO VACUUM SOURCE TO VACUUM SOURCE EGR Vacuum Controls The vacuum signal to the EGR valve may be regulated by one or more of the following: POPPET •...
  • Page 83 Chapter D: Emission Control Systems Diagnosis and Repair Fig. 4-7. Belt-driven pump AIR system. EXHAUST GAS TREATMENT 4. Disconnect the pump hose at the check valve. Start the engine and check for airflow from the open end In addition to exhaust gas recirculation, many engines of the hose.
  • Page 84 Chapter D: Emission Control Systems Diagnosis and Repair Fig. 4-9. AIR control solenoid outputs from the PCM. Component Testing Check Valve Correct operation of the air pump and the various valves A one-way check valve is used to prevent the reverse and switching devices is essential for proper system op- flow of exhaust gasses through the system, figure 4-11, eration.
  • Page 85 Chapter D: Emission Control Systems Diagnosis and Repair fective. Check the connections first, then the valve FREE FLOW assembly. NO FLOW 2. Poor engine performance and surging can result if VALVE DISC one or more of the check valves has failed. This al- VALVE PLATE SPRING (HIDDEN) lows exhaust gas to enter through the air cleaner.
  • Page 86 Chapter D: Emission Control Systems Diagnosis and Repair Fig. 4-12. Three-way converter operation. The oxygen content in a catalyst is important for efficient rear sensor switches is divided by the number of front conversion of exhaust gases. When a lean airfuel ratio sensor switches to determine the switching ratio.
  • Page 87 Chapter D: Emission Control Systems Diagnosis and Repair Fig. 4-13. In order to monitor catalyst operation HO S sensors are mounted before and after the converter. designed for fuel system use. Securely tighten all con- Purge Tests nections. On late-model vehicles the PCM controls purging of the Check that the vapor vent hose leading to the canister is stored vapor with a duty cycle purge solenoid figure 4- properly routed and positioned.
  • Page 88 Chapter D: Emission Control Systems Diagnosis and Repair MANIFOLD VACUUM DIAPHRAGM THROTTLE SPRING BODY PURGE SOLENOID CANISTER TEST PORT VALVE SEAT CANISTER LEAK DETECTION PUMP CARBURETOR BOWL FUEL TANK PURGE VACUUM Fig. 4-15. A simple vacuum-activated canister purge valve for a Fig.
  • Page 89 Chapter D: Review Questions 1. A defect in the PCV system can 4. The downstream HO2S is used 7. On a vehicle without an EVAP leak cause all of the following EXCEPT: PRIMARILY to: detection pump system, the system test passes if: a.

  • Page 90: Chapter E: Computerized Engine Control Diagnosis And Repair (Including Obd Ii)

    Chapter E COMPUTERIZED ENGINE CONTROL DIAGNOSIS AND REPAIR (INCLUDING OBD II) Modern automotive engine management systems use a STORAGE complex network of electronic components to keep the COMPUTER engine operating at peak efficiency with minimal emis- PROGRAMS AND sions, while at the same time delivering an acceptable MEMORY level of performance and driveability.
  • Page 91 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) COMPUTER CONTROLLED ENGINE FUNCTIONS CHECK The output commands of an engine control system reg- ENGINE ulate most, or all, of the following operations: • Fuel metering, fuel injection or a carburetor •...
  • Page 92 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) The third character is a number used by all manufactur- ers to identify which system has a fault. This designa- tion will be the same for P0 (OBD II) or P1 (manufactur- er's) codes.
  • Page 93 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) The result? "HO2S/1, Bank 2 Heater Malfunction", the best procedure is to diagnose and repair the HO2S/1 heater The customer returns the next day with the same malfunction first, even though its DTC is a higher symptoms.
  • Page 94 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) • Run engine for 5 minutes in closed loop, • or until “check engine” light comes on. Light on Light off • Disconnect engine coolant Trouble is intermittent. sensor. Make physical inspection •...
  • Page 95 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) troubleshoot hard codes, figure 5-4. The procedures as- Pre-OBD II vehicles trouble codes should be diagnosed sume that the problem is present at the time of testing. and serviced in a basic order: hard codes first, followed by intermittent codes.
  • Page 96 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) MIL will blink as long the severe misfire is detected. Sensor (TPS) is reporting wide-open, but other sensors are reporting idle speed values, the ECM will set a DTC CATALYTIC CONVERTER - For many vehicles the mon- for the TPS.
  • Page 97 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) indicate more fuel is being added. When the ECM sees Camshaft position is used to identify which cylinder mis- a rich (high voltage) signal from the HO2S, the fuel trim fired.
  • Page 98 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) Fig. 5-5. Fuel trim corrections may be displayed on the scan tool as percentage of correction. Fig. 5-6. The ECM is programed to notice the sudden change in CKP sensor pulses.
  • Page 99 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) Fig. 5-7. When the catalyst is working efficiently most oxygen is used to oxidation and reduction, so post converter voltage fluctuations are Fig. 5-8. As catalyst performance becomes less efficient, less minimal.
  • Page 100 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) Fig. 5-9. The above data can be accessed by the technician using the OBD II scan tool and the Data Link Connector (DLC). faulty circuit or component. Look for unusual circuit ac- conditions exist, perform the following actions: tivity, such as high or low signals, voltage dropout, and •Inspect for an engine coolant temperature (ECT)
  • Page 101 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) noticeably lower than expected. Also fuel economy is Inches of Inches of MAP Sensor Signal Mercury Absolute Voltage (volts) Mercury Vacuum noticeably lower than the economy was on this vehicle 0.5 psi 4.80 31.00...
  • Page 102 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) •Inspect the engine control module (ECM) grounds • What its specific application is for being clean, tight, and in the proper locations. • How it connects to the circuitry •...
  • Page 103 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) only, and the circuit grounds through the sensor hous- accelerator pedal position. Systems may also use a po- ing. With these, a loose mounting or dirt and corrosion tentiometer to measure EGR valve opening, canister on the sensor threads creates resistance on the ground purge valve condition, and vane airflow sensor circuit.
  • Page 104 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) HOLD HOLD mV MAXIMUM mV MAXIMUM 0.00 MINIMUM mV MINIMUM 1200mV 1000mV 1000 200ms/DIV 500ms/DIV RECALL RECALL BACK SEARCH PRINT SELECT BACK SEARCH PRINT SELECT Fig. 5-11. A good HO S scope trace features rounded peaks and Fig.
  • Page 105 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) VHz~ Fig. 5-13. The position of the variable wiper on a potentiometer determines whether the signal voltage will be high or low. Most thermistor failures are due to an open or short cir- THROTTLE POSITION cuit, which can be detected with a digital multimeter SENSOR...
  • Page 106 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) REFERENCE VOLT DROPOUT MANIFOLD SIGNAL PRESSURE PIEZORESISTIVE DEVICE GROUND VOLT MAP SENSOR Fig. 5-16. Manifold vacuum acts on a piezoresistive crystal to provide a variable analog signal to the PCM based on engine load. FIg.
  • Page 107 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) Stepper Motor PULL-UP RESISTOR A stepper motor operates by moving its armature in 5VREF small increments in one direction or the other. A pintel, which does not rotate, is threaded onto the end of the armature shaft.
  • Page 108 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) T = COMPLETE CYCLE TIME t = DUTY CYCLE TIME (PULSE WIDTH) DUTY CYCLE = DUTY CYCLE = t/T = 3/4 = 75% t/T = 1/4 = 25% UNITS OF TIME UNITS OF TIME PULSE PULSE...
  • Page 109 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) POWER V Hz~ V Hz RELAY CIRCUIT RPM+ LAMP CONTROL COIL CIRCUIT CONTROL SWITCH (COMPUTER FUNCTION) GROUND RETURN Fig. 5-20. Applying power to the low current control circuit of a relay closes the contacts to allow high current through the power circuit.
  • Page 110 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) VHz~ VHz~ DISTRIBUTOR BATTERY Fig. 5-22. Ohmmeter connection testing the resistance of a pickup coil. COIL IGNITION problems. One example of this may be a car that idles SWITCH too high because the ECM monitors the battery voltage.
  • Page 111 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) GROUND VHz~ – BATTERY Fig. 5-26. Checking voltage drop at the PCM ground connection. ternator with a dropped diode can severely affect an au- tomotive computer system. To check for AC ripple volt- age, switch your DVOM to AC and connect the black lead to a good ground and the red lead to the "BAT", or power, terminal on the back of the alternator (not the...
  • Page 112 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) nal at a 50 percent duty cycle, the voltage would read 2.5 volts. For automotive applications, when dealing with digital waves, and especially with ECM outputs, we are con- cerned with the amount of time the signal is low, rather then high.
  • Page 113 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) Fig. 5-29. Checking the frequency of a MAP sensor. Fig. 5-28. Checking for voltage ripple from an AC generator. Check Connectors for Damage Intermittent problems are often caused by damaged wiring connectors and terminals.
  • Page 114 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) tem power relay. If so, check the relay. 3. Sensor reference voltage and ground circuits - Many sensors share a common reference voltage supply from the PCM or ECM and a common ground.
  • Page 115 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) 12191490 Connector Part 80 Way F Micro-Pack Series (Blue) Information Wire Color Circuit Number Function BLK/WHT 1551 Ground to G108 1867 LT GRN CKP 12V Reference 1746 Fuel Injector 3 Control PNK/BLK 1745 LT GRN/BLK...
  • Page 116 Chapter E: Computerized Engine Control Diagnosis And Repair (Including OBD II) alytic converter is a two trip monitor, with the additional Warm-Up Cycle condition that the MIL will blink while the severe misfire Warm-up cycles are used by the ECM for automatic is occurring.
  • Page 117 Chapter E: Review Questions 1. The cause of a MIL not lighting 6. Excessive voltage drop across a 10. If total cycle time of a PWM signal during a bulb check when the high resistance ground is 5ms and the solenoid is connection in series with a ignition is switched on can be all energized for 2ms during each...

  • Page 118: Index

    Index Chapter A Variable Valve Timing ..... .19 COOLING SYSTEM SERVICE ... .20 CUSTOMER INTERVIEW .
  • Page 119 Index Electronic Component Testing ....36 Volume Test ......57 Secondary Circuit Diagnosis and Repair .
  • Page 120 Index Thermostatic Vacuum Switch Test ...74 Road Test and Record Data ....93 Spark Delay Valve Tests ....74 Diagnosis Of Emissions And Drivability Problems .

  • Page 121: Sample Test

    Sample Test TEST TAKING ADVICE will be less likely to doubt yourself while reading the an- swers. As soon as you make the decision to schedule an L1 test, begin preparing by including dedicated study timein your Note all operating conditions stated in the question when weekly schedule.
  • Page 122 Sample Test 7. When the positive voltmeter lead of 12. On an oscilloscope raster display of 17. Technician A says that a good me- a voltmeter is connected to the pos- the secondary ignition system, the chanical fuel pump will deliver about itive (battery) coil terminal and the most likely cause of an 8 to 10 de- a quart, or liter, of fuel per minute at...
  • Page 123 Sample Test 31. Technician A says that too much 22. An unmetered air leak downstream 26. Technician A says that the idle air of the airflow sensor can cause: control (IAC) valve may have to be valve lash clearance can increase disconnected to perform a cylinder the effective camshaft duration and a.
  • Page 124 Sample Test 35. Problems in the cooling system can 41. The starter control circuits includes 46. All of the following are methods to relieve fuel pressure EXCEPT: cause all of the following EXCEPT: all of the following EXCEPT: a. Increased emission levels a.
  • Page 125 Sample Test 52. Technician A says a four-gas ex- 56. Technician A says a thermistor is a 59. Which of the following sensor sig- haust analyzer is not used to meas- sensor that provides variable resist- nals is NOT used during open loop ure Oxides of Nitrate (NOx).

  • Page 126: Glossary

    Glossary Actuator: A device that receives a voltage signal or com- Catalyst: Specific compounds that enhance a chemical mand from a computer and responds by performing a me- reaction without being consumed by the reaction. chanical action. Centrifugal Advance: A method of advancing the ignition Air-Fuel Ratio: The ratio of air to fuel by weight of the air spark using weights in the distributor that react to centrifu- and fuel mixture drawn into the engine.
  • Page 127 Glossary Drive-by-Wire: A throttle control system which relies on High-Impedance: A high level of opposition to current cre- electronic signals from the accelerator pedal position sen- ated by the combined forces of resistance, capacitance, sor to direct the PCM or throttle actuator control module to and inductance in a circuit.
  • Page 128 Glossary Oscillations: Steady, uninterrupted up-and-down swings, Sensor: A device that provides an electric signal to a com- or waveforms. puter to indicate a certain physical condition. In an automo- tive electronic system, sensors monitor such conditions as Oscilloscope: An oscilloscope is an instrument commonly vehicle speed, throttle opening, or steering angle.
  • Page 129 Glossary Top Dead Center (TDC): The point in engine rotation when Voltmeter: A voltmeter is an instrument used for measur- cylinder number one is at the top of its travel and the valves ing the potential difference, or voltage, between two points are closed.

  • Page 130: Test Answers

    Test Answers Chapter A: Chapter D: Sample Test: 1. c, 2. a, 3. b, 4. a, 5. c, 6. c, 7. d, 8. 1. d, 2. b, 3. c, 4. a, 5. a, 6. c, 7. d, 8. d 1. b, 2. a, 3. d, 4. b, 5. b, 6. a, 7. c, c, 9.

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