Subaru Basic Emission Fuel Systems 405
Contents
1. Slide No Description page No 1 Title Slide Basic Emission and Fuel System 2 Created By 3 Teaching Aids 4 Title Slide Introduction 8 5 Beauty Shot Impreza Legacy SVX 8 6 Title Slide Raw Materials for Combustion 8 7 Legacy Mountain Shot 8 8 Storage Tank 9 9 Atmosphere Pie Chart 10 10 Vacuum 10 11 Intake Stroke 10 12 Ported Vacuum 11 13 Title Slide Combustion Process 11 14 Power Stroke 11 15 Combustion Process 11 16 Complete Combustion 11 17 Incomplete Combustion 12 18 Nitrogen During Combustion 12 19 NOx Production 12 20 Definitions 12 21 Condition 1 Condition 2 13 22 Condition 3 Condition 4 13 23 Condition 5 Condition 6 13 24 Catalytic Converter 13 25 Normal Catalytic Operation 13 26 SO Production 14 2 Title Slide Tumble Generator Valve 14 28 Runner Intake 14 29 Stepper Motor 14 30 Vent Hose 14 EN TGV Sensor 15 32 Manifold Bottom View 15 33 TGV Passage 15 34 TGV Close Open 15 35 Oxygen Sensor 16 36 0 Sensor 16 37 Voltage Chart 16 38 AFR Artwork 16 39 Title Slide Closed Loop 17 40 Closed Loop 17 41 Stoichiometric Window 17 42 Sea Level 17 August 2001 Slide No Description page No 43 Title Slide Exhaust Gas Recirculation 18 44 EGR Conventional 18 45 Vacuum Diagram 1995 and Newer EGR 18 46 BPT Operation Off 19 47 BPT operation On 19 48 Title Slide Evaporative Emissions2. SUBARU 4 gt QUALITY DRIVEN SERVICE Technicians Reference Booklet Basic Emission and Fuel Systems Module 405 AUTOMOTIVE duc MSA5P0160C d Technical Training Subaru of America Inc 2001 O Copyright 2001 Subaru of America Inc All rights reserved This book may not be reproduced in whole or in part without the express permission of Subaru of America Inc Subaru of America Inc reserves the right at any time to make changes or modifications to systems procedures descriptions andillustrations contained in this book without necessarily updating this document Information contained herein is considered current as of August 2001 TT05079 01 Basic Emission and Fuel Systems Table of Contents GI E ET 5 Se EST TE 6 ee jo Ed fo EEN 8 Raw Materials For Combustion iaassizaaocnesainiasassiasoisacaiinihaca ENK NeEeNEEEe GENEE sounds hindu danb ca 8 LOW Volatility Agen doping e dado nai dean dd rd aan ga da asa o natas ainda 9 alle IR E UE PR SR RR RR RR ORE RP RR EP aek a 9 Phase Separati n E 9 Reformulated and Oxygenated Fuel c ccccssseeeeeeeeeseeesseeneeeeeeeeseeeeeeeeeeeeeeeseseeneeeeeeeeeees 10 OCIANO E ara es tenet sabor ee ee 10 UE EE e eege ege EE degkeet 10 VACUUM DeoteaR ER Per RR AR RNA ORE RR RAR RR A POR RR 10 GOMbDUSHON PROCESS E do ged eEBE Eege Ee Ehe ideia 11 Catalytic Converter E 13 Tumble Generator Valve caiam iastatiiaiini iara donas eeebegeke en eeh eE aa ii
3. Control 19 49 Conventional Evaporative 19 50 Enhanced Evaporative 20 51 Canister 20 52 Pressure Control Duty Solenoid 20 53 Vent Control Solenoid Valve 20 54 Air Filter 21 55 Roll Over Valve Side In Normal Vehicle Position 21 56 Roll Over Valve Side With Vehicle On Its Side 21 57 Roll Over Valve Roof With Vehicle On Its Roof 21 58 Title Slide System Operation 22 59 While Driving 22 60 While Refueling 22 61 Title Slide Pressure Sources Switching Operation 23 62 1995 and Newer Manifold 23 63 Title Slide Fuel Delivery Quick Connector 23 64 Quick Connector 23 65 Quick Connector Service 23 66 Title Slide and Artwork ECT Engine Coolant Temperature Sensor 24 67 Title Slide Crankcase Emission Control 24 68 Light Load 24 69 Heavy Load 24 70 Copyright 71 The End August 2001 August 2001 Basic Emission and Fuel Systems Introduction Today s automobile is the refinement of research which through the years has led to a computer controlled machine sensitive to both internal and external influences Itis able to provide optimum performance throughout a broad range of atmospheric conditions fuel quality engine condition and driver demand The information covered in this course will get you started with the knowledge base you must have to effectively analyze conditions situations and problems associated with vehicle emissions The majority of the course will be conducted in a lab lecture format You are required to be an a
4. System Diagnostic Link Connector DLC Location 11 59 00 02 25 00 1999 Legacy Impreza Forester Air Intake Chamber Box Breakage 11 61 00 06 01 00 All Subaru Vehicles State Emission Test Fuel Filter or Gas Cap Test 11 62 00 05 08 00 All 2001 Models Subaru Vehicles On Board Diagnostic System Check During State Emission Test 11 63 00 11 01 00 1980 1989 MY Subaru Vehicles Pressure Testing of Fuel Tank System During State Emission Test 11 64 01 02 01 01 All 1996 1999 Legacy Postal Vehicles On Board Diagnostic System Diagnostic Link Connector DLC Location 28 August 2001 Basic Emission and Fuel Systems 405 Module Service Help Line Updates Date Subject 03 95 Legacy and Impreza engines with no injection pulse 1 cylinder 03 95 Impreza air suction valve noise 06 95 1995 Subaru Legacy DTC P0505 Idle control system malfunction 06 95 1995 Subaru Legacy DTC P0325 Knock sensor circuit malfunction 06 95 1995 Subaru Legacy DTC P0130 Front 02 sensor circuit malfunction 07 95 Rough idle on MPFI vehicles 07 95 94 Impreza ROM sockets 09 95 DTC P0505 idle control system when solenoid measures 5Q or less 12 95 Extreme cold weather engine warm up and OBD II 07 96 Loose fuel caps and trouble code P0440 09 96 1997 Legacy warranty claims for loose fuel caps 09 96 Legacy Non Turbo SVX and Impreza ISC valves 11 96 P0440 and Legacy fuel caps 11 96 Blue vs Gray connectors during diagnosis 11 96 Extreme cold weather engine war
5. back side of the valve vent diaphragm Orifice chamber Drains fuel from the pressure difference detecting line into the tank Shut valve Closes the evaporation line when a filler gun is inserted into the filler neck Prevents fuel vapors from escaping to atmosphere while refueling Tank pressure sensor Monitors fuel tank pressure for diagnosis e Vent line Directs fuel vapors from the valve vent to the cannister during the time the vehicle is being refueled flow of fuel vapors from the tank to the cannister except during the time the vehicle is being refueled And controls the flow of atmospheric pressure to the tank when a negative pressure develops Drain Valve Provides a pathway to atmosphere for air after the fuel vapors have been removed by the charcoal element of the cannister Only during the time the vehicle is being refueled System Operation While driving Shut valve Open PCV Open or Close Drain valve Open 59 ORVR System The fuel tank pressure is applied to one side of diaphragm inside the Pressure Control Valve When the pressure is greater than atmospheric a port inside the PCV opens allowing fuel vapors to the cannister If negative pressure exists the PCV opens allowing atmospheric pressure to the fuel tank While refueling As fuel fills the tank the air inside the tank is displaced caring fuel vapors with it This large increase in press
6. NOx to CO2 Nitrogen also enables it to store oxygen during times of a lean mixture and bring it into the conversion process during times of ric mixtures An operating temperature of at least 600 F 315 55 C is required for the catalytic converter to operate Catalytic Converter Normal Catalytic Operation August 2001 13 Basic Emission and Fuel Systems The Nickel content of Catalytic converts has been Tumble Generator Valve reduced in recent years because of its natural ability as a reducing agent o o 26 SO Production This characteristic normally is beneficial to the reduction of harmful emissions but if the fuel is sulfur contaminated the results is the production of Hydrogen Sulfide H2S Federal regulations state that there can only be 1 10 of 1 sulfur content in fuel Removing sulfur from crude oil is an expensive and difficult procedure sometimes yielding poor results Sulfur content higher than the Federal specification creates the sulfur contaminated fuel Initial combustion of the contaminated fuel produces SO2 SO2 burned in the catalytic converter creates SO3 SO3 absorbs water very easy and produces H2S04 Some of the SO2 created at combustion will flow across the Nickel which strips or reduces an oxygen molecule from it and a Hydrogen molecule will replace it Yielding H2S the aromatic that smells like rotten eggs Stepper Motor The EJ 2 0 is equipped with a tumble generato
7. altitudes have less dense air it weighs less because its closer to the beginning of the 110 mile high column e E 4 10 Miles lt 8 Miles SEA LEVEL Sea Level Atmospheric Pressure Maintaining stoichiometric air fuel mixture in this condition becomes more difficult The atmospheric pressure can be increased in the engine with turbo chargers and super chargers The introduction of additional air to the air fuel mixture will compensate for the less dense air August 2001 17 Basic Emission and Fuel Systems Exhaust Gas Recirculation LH cylinder head EGR solenoid valve OD Exhaust port Throttle body EGR valve Exhaust Gas Recirculation Preventing the production of harmful emissions is the best way to keep them from the atmosphere NOx emissions control is performed by the Exhaust Gas Recirculation EGR system The EGR system when activated displaces 6 to 13 of the normal air in the intake manifold Part of the exhaust is routed through the EGR valve to the intake manifold This EGR gas has already burned containing little oxygen and fuel Mixed in the combustion chamber with normal air and fuel the EGR gas reduces the heat because the EGR gas will not effectively burn The heat generated with normal air surrounding the EGR gas is absorbed by the EGR gas and exits the engine as exhaust This action lowers the overall combustion chamber temperature controlling th
8. ctive member of the class Take notes and complete the lab structured work sheets A completion test will be given at the end of the class based on information covered in lecture and hands on exercises Raw Materials For Combustion To fully understand the emissions produced by a vehicle a closer look at the raw materials used must be made They include fuel and the atmosphere The fuel or gasoline is a hydrocarbon made from a mixture of components which vary widely in their physical and chemical properties Gasoline must cover a wide range of vehicle operating conditions engine temperature climates altitudes and driving patterns There are many driveability conditions that can be caused from gasoline problems One such problem is incorrect fuel volatility Volatility is a fuels ability to change from a liquid to a vapor Gasoline refiners must chemically adjust their product seasonally providing more volatile gasoline in the winter and less in the summer There are many ways of measuring volatility however there is only one practical way you can check it in your shop That is the vapor pressure test using the Reid Method August 2001 Basic Emission and Fuel Systems Problems associated with incorrect Volatility Low Volatility Cold Start Warm up performance Cool weather performance Cool weather drive ability Increased deposits of the combustion chamber High Volatility High evap emissions Hot drive abilit
9. de of the AFR is covered by a porous chamber that allows the exhaust gas access to the Zirconia center while the outside of the AFR sensor is exposed to the atmosphere Oxygen ions pass from the exhaust side to the atmospheric side during lean engine operation and from the atmospheric side to the exhaust side during rich engine operation Stoichiometric engine operation will result in no ion exchange August 2001 16 Basic Emission and Fuel Systems Closed Loop DUTY SOLENOID Closed Loop Closed loop is a description of fuel injection and engine management operation where both systems are monitored and adjusted Closed loop relies on input from sensors that monitor engine operation Providing precise control to increase power and reduce emissions Open loop is a description of the fuel injection and engine management systems that provide the best operating conditions during Cold engine operation near full throttle and fail safe Stoichiometric Window 100 NOx co 80 HC 60 Conversion Efficiency 49 20 0 13 1 14 711 Air Fuel Ratio Stoichiometric Window Maintaining the ideal air fuel mixture that creates the most power and lowest emissions is referred to as Stoichiometric At sea level the weight of the atmosphere is 14 7 pounds per square inch This column of air extends from the ground to approx 110 miles straight up This 14 7 psi burned with 1 pound of fuel is stoichiometric Higher
10. e normally creates 115 000 BTU s per gallon Reformulated or Oxygenated fuel will produce only 76 000 BTU s per gallon Ethanol and Methanol are the two alcohols used in oxygenated gasoline Methanol is a wood alcohol and can be used up to 5 with most auto manufactures However it is very corrosive and many cosolvents and rust inhibitors must be used with it to prevent damage to the fuel system Ethanol or grain alcohol is not as corrosive and is allowed up to 10 Octane Atmosphere Octane is defined as a fuels ability to resist knock The atmosphere is composed of 79 nitrogen Also known as the Anti Knock Index AKI is the 20 oxygen and 1 inert gases f the Mot nd Research Octane Number RON aie Each intake stroke fills the cylinder with these gases This action also produces vacuum R M 2 Laboratory tests determine MON and RON There is no advantage in using a higher Vacuum octane than it takes to prevent engine knock Engine knock is created by using a lower octane than is required Heat and pressure will ignite the air fuel mixture before the spark creating an uneven burn across the combustion chamber Subaru ignition timing learning control logic memorizes when the engine knock occurs and retards the timing away from optimum to compensate Manifold Vacuum There are two types of vacuum or negative pressure produced by the engine The first to be produced in a measurable amount is called Intake ma
11. e production of NOx emissions The EGR valve is operated with a ported vacuum signal that is controlled by the EGR solenoid Solenoid activation is dependent on ECM logic EGR systems used on later model vehicles are controlled with a solenoid and a Back Pressure Transducer BPT Ported vacuum enters the BPT at line R this will be E used as working pressure Ported vacuum enters the BPT at line P this will be used as control pressure throttling vacuum in line R to line Q Exhaust enters the bottom of the BPT pushing the diaphragm assisting the pressure at line P This action continues during all engine operation however the EGR valve will not operate until the ECM grounds the EGR solenoid 1 EGR Valve 2 EGR Solenoid 3 Back Pressure Transducer 4 Throttle Body 45 Vacuum Diagram Most 95 and Newer EGR August 2001 18 Subaru Basic Emission and Fuel Systems Evaporative Emissions Control Subaru vehicles are equipped with either a Conventional or Enhanced Evaporative Emissions Control System Both systems function to prevent unburned Hydrocarbons from escaping to the atmosphere Bleed hole Q Purge control solenoid valve Exhaust Pressure BPT Operation EGR Off Two way valve Canister Fuel tank Bleed hole q Conventional Evaporative System Conventional Evaporative components include the following 1 Fuel Cap Construction incorporates a relief va
12. ector until an audible click is heard Confirm connection by pulling the connector backward Also check that the two pawls of the retainer are engaged to the connector Replacement part is the retainer only Quick Connector Service August 2001 23 Basic Emission and Fuel Systems Engine Coolant Temperature Crankcase Emission Control Sensor Crankcase Emission Control System Functions to prevent blow by gases from entering the Connector atmosphere Components include Sealed rocker covers hoses PCV valve and Air intake duct Throttle chamber Intake manifold Air intake duct PCV valve Fresh air Mixture of air and blow by gas Thermistor element 66 ECT Engine Coolant Temperature Sensor ECT functions to monitor coolant temperature Resistance of the sensor with cold coolant is high Reference voltage from the sensor will be Operation is performed in two modes Crankcase low Resistance of the sensor with warmer coolant Mode one Light engine load Air flows in to is low Reference voltage will be higher the air duct and part of the air is routed to the Reference voltage signal changes are used to rocker covers Vapors and air enter the PCV influence ignition timing injection duration and because of the negative pressure at the idle speed Some models use ECT signal to valve control radiator fan motor relays Fail safe on these models will result in constan
13. end atmosphere through the evaporative canister Enhanced evaporative systems access atmosphere through an extension of the PSSS The Pressure sensor Functions to monitor manifold and atmospheric pressure PSSS position determines pressure source Changes in pressure positive or negative produce a changing reference voltage signal Reference voltage signal changes are used to influence ignition timing and injection duration Canister purge flow is also monitored with the Pressure Sensor PSSS switches to atmosphere While the purge control solenoid is on Fuel Delivery Quick Connector The fuel system of the forester is very similar to past models with enhancements to tank capacity clamps and delivery line The resin delivery line between the fuel pump and the 60 liter fuel tank are connected by a one time use only Quick Connector This Quick Connector must be released when removing the fuel pump or fuel tank C the directions in the appropriate service manual before removing any fuel lines Quick Connector Quick connector service procedure 1 Separation Pushing the retainer with a finger in the arrow direction pull the connector to separate it After separation the retainer will remain attached to the pipe 2 Connecting Check the connecting portion of the pipe visually If a scratch or foreign particle exists on it wipe them off of the pipe into the conn
14. i aaa nda 14 Oxygen SCNSONS deed a Apa a ad ei oidean 16 Closed LOOP EE 17 Exhaust Gas RecirCuIation sssini dias dada EU REESEN ENEE 18 Evaporative Emissions Control zosegsrtoeueekeeeuegbiegekeeeeguegeguEEuENEK ao iadana ns duna aninha ud od nenna 19 On Board Refueling Vapor Recovery cccccccsssseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeeeeeeeeneeseeaeeeeees 22 Components include eeben beten eteggeegeg geet DEAEEEER veios doi ee EEKE E EEGEN 22 System Operalon air avin dae as oia O a ia a ae 22 OUER AT a o EE 22 WHINE FOTU KEE 22 Pressure Sources Switching Operation cccccceeseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeenees 23 Fuel Delivery Quick Connector icciindissveccwineiscinesasaentansannianadees ndasabeners eEEVeEER densa das alan 23 Quick connector service procedure eccccsesseseeeeeeeeeeeseeeeeneeeeeesenseeeeeeeeeeeeeesseeneeeeeeeees 23 Engine Coolant Temperature Sensor sssssseeeeeeeeeeeeeeseeeeeeeeeeeseeeeeeeeeeeeeeeesseeneeeeeeeeeesesseeees 24 Crankcasa EMISSION Control aisisasisasiaiisssooscoaminiiniisiiosiidandniuha dao adaide india idade e ninia iba cida ibid 24 State I M Program Advisories Bulletins and Service Bulletins nn 28 405 Module Service Help Line Updates ccccsssseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeneees 29 August 2001
15. l Condition E Loose Knock Sensor B Rich H Open Coolant Temp Sensor C Lean G Clogged Injector D Lean Misfire H Open Plug Wire HC hydrocarbons 75 PPM CO carbon monoxide 0 1 0 oxygen 9 0 CO carbon dioxide 5 0 NO oxides of nitrogen 1000 PPM CONDITION 2 CONDITION 1 Condition 1 Condition 2 HC hydrocarbons 20 PPM CO carbon monoxide 0 0 0 oxygen 9 0 CO carbon dioxide 5 0 NO oxides of nitrogen 800 PPM HC hydrocarbons 350 PPM CO carbon monoxide 3 0 0 oxygen 9 0 CO carbon dioxide 0 1 NO oxides of nitrogen 11 PPM CONDITION 4 CONDITION 3 Condition 3 Condition 4 HC hydrocarbons 850 PPM CO carbon monoxide 0 3 0 oxygen 8 0 CO carbon dioxide 5 0 NOx oxides of nitrogen 800 PPM HC hydrocarbons 1200 PPM CO carbon monoxide 0 3 0 oxygen 8 0 Eft carbon dioxide 8 0 NOx oxides of nitrogen 800 PPM 19 z H E a 2 0 o D 2 H E a 2 H 0 Condition 5 Condition 6 Catalytic Converter Reducing HC CO and NOx is the objective of the catalytic converter The converter is made of a honey comb ceramic structure held in place with a Nickel support shell all contained in a metal housing Rare nobel metals Platinum Palladium and Rhodium are adhered to the ceramic structure These two metals give the catalytic converter a 3 way operating characteristic When in operation the converter will change CO HC and
16. lve that allows air to enter the tank in the event a vacuum develops 2 Canister Temporarily stores evaporative gas from the fuel tank 3 Purge control Solenoid valve Controls the BPT Operation flow of stored evaporative gas from the EGR On Exhaust Pressure canister to the intake manifold 4 Two way valve Controls air flow to the fuel tank High tank pressure opens the valve allowing the pressure and evaporative gas to the canister Low tank pressure closes the valve allowing atmosphere to the fuel tank through a pinhole in the valve 5 Fuel cut valve Used on AWD models Prevents liquid fuel from entering the evaporative line Fuel separator allows fuel vapor to condense and return to the tank as liquid Some models use a plastic tank mounted in the trunk or cargo areas Other models use an air space designed into the fuel tank to condense fuel vapors August 2001 19 Basic Emission and Fuel Systems System operation The ECM grounds the purge control solenoid turning it on Ported vacuum then removes the stored evaporative gas from the canister System activation is controlled using coolant temperature engine load and vehicle speed input Purge control solenoid valve Canister Throttle body Fuel tank pressure sensor Vent control solenoid valve Fuel cut val Fuel level uel cut valves Ki Roll over valve Pressure control 50 Fuel tank Fuel temperat
17. m up and OBDII 03 97 DTC P1500 radiator fan relay one circuit 03 07 1997 Subaru Impreza Outback Sport 04 97 Understanding P0440 05 97 DTC P0507 Idle control system RPM higher than expected 07 97 Code P0500 07 97 Additional information regarding code P0440 08 97 OBD II cylinder misfire codes 10 97 More P0440 information 01 98 Exhaust smell during cold start 01 98 amp 05 98 Model Year 1998 changes in P0440 Evap operation 05 98 DTC P0440 Revisited 11 98 P0440 TIP 11 98 DTC P1507 05 99 DTC P0705 diagnostics 08 99 Freeze frame data 09 99 Evaporative system diagnosis 11 99 OBD readiness codes 11 99 P0440 1998 1999 Forester 11 00 WXV 79 engine control module service program August 2001 29 Subaru of America Inc
18. nifold vacuum It is produced by the intake stroke of the engine August 2001 10 Basic Emission and Fuel Systems The second type is Ported vacuum Itis produced by the volume and speed of the air entering the engine The positioning of the throttle plate determines the amount produced and at what spot in the throttle bore it is located This effect enables the ported vacuum to be used as a working pressure and a controlling pressure Ported Vacuum Combustion Process Combining fuel and atmosphere in the combustion chamber under pressure and supplying a spark changes chemical energy to heat energy The resulting gas expansion pushes the piston down Power Stroke Combustion splits gasoline or HC Engine temperature compression fuel purity ignition timing and the mechanical condition of the engine determine the degree of complete combustion This ultimately determines the amount and type of exhaust emissions produced Near complete combustion will join oxygen with hydrogen and form water The carbon will join with oxygen to form CO2 Carbon Dioxide 11 Combustion Process Complete combustion is very hard to achieve because of uneven engine temperatures random fuel impurities and many other situations however in theory if complete combustion did take place one gallon of gasoline would produce one gallon of water Complete Combustion Incomplete combustion occurs when the enti
19. ol solenoid open Purge Control Duty Solenoid active High fuel tank pressure Pressure control solenoid valve open Fuel caps of both systems have a vacuum relief valve that allows atmospheric pressure to enter the fuel tank This prevents vacuum from forming as the fuel is used and acts as a back up for the two way valve Ball valve A Roll Over Valve In Normal Vehicle Position Both systems use a rollover valve located under the center rear of the vehicle Rollover valve operation prevents fuel from flowing through the evaporative line in event of vehicle rollover Valve operation is performed by gravity and the position of two Ball Valves Roll Over Valve With Vehicle On Its Side Roll Over Valve With Vehicle On Its Roof August 2001 21 Basic Emission and Fuel Systems On Board Refueling Vapor Recovery This system will be used on all 2 2 liter Legacy and Impreza vehicles Forester will be equipped with ORVR beginning approximately with October production ORVR controls the pressure inside the fuel tank and collects fuels vapors during all vehicle operating conditions and during the time the vehicle is being refueled Components include Fuel cut valve FCV Prevents liquid fuel from entering into the evaporative line Valve vent Controls the flow of fuel vapors during the time the vehicle is being refueled Pressure difference detecting line Directs atmospheric pressure e to the
20. oxygen content of the atmosphere to the oxygen content of the exhaust Materials making up the oxygen sensor generate a small voltage that represents the air fuel mixture This electrical signal is sent to the ECM so that adjustments can be made reducing harmful HC emissions Rich air fuel mixtures generate higher voltages no higher than 1 volt and lean air fuel mixtures generate lower voltages closer to 300 millivolts 02 SENSOR OPERATION 0 LEAN AIR FUEL RATIO RICH 37 Voltage Chart Oxygen Sensor Operation The normal color of the oxygen sensor tip is gray White indicates the sensor has been operating in a constant lean air fuel mixture Black indicates a constant rich air fuel mixture Diagnose the fuel and engine management system if the color of the sensor is other than grey as the response time or sensitivity of the sensor has been affected The Air Fuel Ratio Sensor is used on 1999 California Models Located in place of the front Oxygen Sensor the AFR begins to operate and effect the Air Fuel Ratio faster than conventional Oxygen Sensors Zirconia remains the key material in AFR construction It s ability to absorb oxygen and new ECM circuitry work together to provide fast accurate data Rich range Stoichiometric Point Lean range Ex Gas Ex Gas E A contact plate is located on the top and bottom ofa layer of Zirconia These plates are connected to wires that lead to the ECM The exhaust si
21. r valve at each intake runner This new system uses a Shaft for each side of the engine that is driven by astepper motor The movement of the shaft is monitored by a sensor on the opposite end Vent Hose August 2001 14 Basic Emission and Fuel Systems When the plate is closed the main air passage through the intake runner is blocked This will force all air necessary for engine operation during idle to flow through the bypass channel This action helps to mix the air fuel mixture by producing a tumbling effect to the incoming air resulting in a cleaner operating engine while idling TGV Sensor Tumble Generating Air Passage The shaft operates the tumble generator valve which is a plate similar in design to the throttle plate At idle the plate is closed dependant on coolant temperature and time from engine start e d Passage Off idle the plate is open TGV Close Open TGV Passage August 2001 15 Basic Emission and Fuel Systems Oxygen Sensors Oxygen sensors function to determine the amount of oxygen in the exhaust The sensor is located upstream of the catalytic converter and monitors the exhaust as it leaves the engine Rich air fuel mixtures will have very little oxygen in the exhaust while lean mixtures have much more by comparison Ceramic heater Zirconia tube O2 Sensor The oxygen sensor after reaching an operating temperature of 600 F 315 55 C compares the
22. re fuel charge is not burned in the combustion chamber Unburned HC will be exhausted to the atmosphere if the exhaust remains untreated Carbon will still join with oxygen but with only one part so the result is the production of Carbon Monoxide CO This gas is very unstable If inhaled 3 of 1 in a 30 minute time frame will create Carbon Monoxide Poisoning which can be fatal HC and CO are both harmful to the atmosphere August 2001 Basic Emission and Fuel Systems HYDROCARBONS HC measures in Pem 75 PPM Result of incomplete combustion raw fuel CARBON MONOXIDE CO measured in 0 5 Result of fuel burnt without enough air OXYGEN 02 Measured in so 0 Result of a lean running engine 0 5 CARBON DIOXIDE C02 measured in 2 Result of an efficient running engine 13 5 17 OXIDES OF NITROGEN NOx measresiw rem ANA PN Result of combustion chamber temperatures over 2500 F Incomplete Combustion Another harmful gas is oxides of nitrogen NOx The x is an indicator that the number of oxygen molecules is unknown NOx is produced from Notes high pressure and heat in excess of 2500 F 1371 1 C in the combustion chamber Nitrogen During Combustion NO Production August 2001 12 Basic Emission and Fuel Systems Review the analyzer readings below and choose the correct answer that best describes the condition Write the corresponding letter on the space provided below A Norma
23. t radiator fan Ed En EE operation Air intake duct PCV valve Fresh air Mixture of air and blow by gas Blow by gas Crankcase Mode two Heavy engine load Air flows in to the air duct and produces a negative pressure at the rocker covers This action carries the vapors from the crankcase into the throttle body August 2001 24 Basic Emission and Fuel Systems Notes August 2001 25 Basic Emission and Fuel Systems Notes August 2001 Basic Emission and Fuel Systems Notes August 2001 27 Basic Emission and Fuel Systems State UM Program Advisories Bulletins and Service Bulletins No Date Title Subject 11 50 97 12 05 97 All Subaru Full Time AWD Models State Emission Testing 11 51 97 12 05 97 All Subaru Full Time AWD Models Diagnostic Service Cautions 11 52 98 05 22 98 All 1999 Model Subaru AWD Models State Emission Testing 11 49 97R 09 02 98 1996 MY Legacy Impreza amp SVX OBD Check During State I M Program 11 53 98 01 05 99 97 98 Legacy Impreza and Forester Manual Transmission vehicles with 2 5L amp 2 2L engines Hesitation On Acceleration 11 54 99 03 01 99 All 1996 1999MY On Board Diagnostic System Diagnostic Link Connector DLC Location 11 55 99 03 17 99 All 1996 2000MY On Board Diagnostic System Check During State Emission Test 11 56 99 09 08 99 All 2000MY State Emission Testing 11 57 99 09 29 99 All 2000 MY On Board Diagnostic
24. ure opens the valve vent allowing the fuel vapors to the cannister The continued filling of the tank pushes the remaining air and fuel vapors through the cannister The charcoal element of the cannister absorbs the fuel vapors an directs fuel vapor free air to the atmosphere though the Drain valve and air filter e PCV Pressure Control Valve Controls the Evaporation gas Shut valve Close PCV Close Valve vent Open Fresh air Drain vent Open 60 While Refueling The PCV is checked for circuit malfunction Drain valve checks include circuit and performance checks August 2001 22 Basic Emission and Fuel Systems Used on 1995 and newer vehicles equipped with OBDII Functions from an ECM ground Pressure Sources Switching Operation TO CANISTER FRONT OF VEHICLE 1 Fuel Pressure Regulator 2 Throttle Body 3 Canister Purge 4 Pressure Sensor 5 Pressure Sources Switching Solenoid 6 EGR Solenoid 7 EGR Valve 8 Back Pressure Transducer 1995 and Newer Manifold Pressure sources switching solenoid PSSS signal and Switches to allow atmospheric pressure to the pressure sensor during engine start and every 30 minutes or 3 1 miles 5 kilometers Switches to allow manifold pressure sensor when not switched to atmosphere The passage way to atmosphere on Conventional evaporative systems access Align the pipe and the connector insert the
25. ure solenoid valve ensor Enhanced Evaporative System Enhanced Evaporative components include 1 Canister Function is unchanged however the shape is more boxy and is located under the right rear of the vehicle To purge control solenoid valve From fuel tank Canister 2 Pressure control duty solenoid Adjusts the pressure inside the fuel tank from a signal from the ECM It also controls the flow of evaporative gas from the fuel tank to the canister Connector terminal J LA A ee e WEE SS A fall ON To canister lt Eis lt From fuel tank Pressure Control Duty Solenoid 3 Vent Control Solenoid Valve Controls the flow of atmospheric pressure to the canister During normal operation the valve is open allowing atmospheric pressure to the canister During the time the ECM is checking the integrity of the evaporative system the valve is closed to isolate the system from atmosphere Vent Control Solenoid Valve 4 Air Filter Filters air as it enters the vent control solenoid valve 20 August 2001 Basic Emission and Fuel Systems Air Filter 5 Fuel Tank Pressure Sensor Monitors fuel tank pressure and sends an input signal to the ECM System operation Optimum purge control is programmed in the ECM and is influenced by engine load coolant temperature and vehicle speed Low fuel tank pressure Pressure control solenoid valve closed Vent contr
26. y Vapor lock Poor fuel mileage There are six volatility classes of gasoline Record their values on the spaces below AA moO WwW gt Higher volatile fuels will evaporate easier than lower volatile fuels so higher pressure readings will be achieved WATER ALCOHOL MIXTURE Storage Tank Phase Separation Another problem of today s gasoline can be created if the fuel is stored in a water contaminated tank Referred to as Phase separation this condition results because of the use of alcohols as octane boosters and oxygenates The alcohol in the gasoline will absorb the water in the tank and separate from the gasoline This new heavier mixture will settle in the bottom of the storage tank Sooner or later someone will get a tank full or enough of it pumped into their vehicle to cause a drive ability problem Oxygenates or alcohols are used in fuels where lower emission output is required by state or federal regulations These fuels are called Reformulated or Oxygenated fuel The difference between the two is the amount of additional oxygen they supply to the combustion process August 2001 Basic Emission and Fuel Systems Reformulated and Oxygenated Fuel Atmosphere Reformulated fuel contains 2 oxygen by weight Oxygenated fuel contains 3 5 oxygen by weight There is a trade off with use of either of these fuels and that is a 2 fuel economy loss and less energy output per gallon Gasolin
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