TechniciansReference

Booklet

Basic Emissionand

Fuel Systems

Module 405

MSA5P0160C

© Copyright 2001Subaru of America, Inc.

All rights reserved. This book may not be reproducedin whole or in part without the express permission ofSubaru of America, Inc.

Subaru of America, Inc. reserves the right at any timeto make changes or modifications to systems,procedures, descriptions, and illustrations containedin this book without necessarily updating thisdocument. Information contained herein is consideredcurrent as of August 2001.

© Subaru of America, Inc. 2001 TT05079/01

Table of Contents

Slide Sequence .................................................................................................................... 5Slide Sequence .................................................................................................................... 6

Introduction ............................................................................................................................... 8Raw Materials For Combustion ................................................................................................ 8

Low Volatility - ...................................................................................................................... 9High Volatility - ..................................................................................................................... 9Phase Separation................................................................................................................. 9Reformulated and Oxygenated Fuel ................................................................................. 10Octane ................................................................................................................................. 10

Atmosphere ............................................................................................................................. 10Vacuum .................................................................................................................................... 10Combustion Process .............................................................................................................. 11Catalytic Converter.................................................................................................................. 13Tumble Generator Valve ......................................................................................................... 14Oxygen Sensors ...................................................................................................................... 16Closed Loop ............................................................................................................................ 17Exhaust Gas Recirculation ..................................................................................................... 18Evaporative Emissions Control ............................................................................................. 19

On Board Refueling Vapor Recovery ............................................................................... 22Components include: ........................................................................................................ 22

System Operation .................................................................................................................... 22While driving ....................................................................................................................... 22While refueling.................................................................................................................... 22

Pressure Sources Switching Operation ................................................................................ 23Fuel Delivery Quick Connector .............................................................................................. 23

Quick connector service procedure. ................................................................................ 23Engine Coolant Temperature Sensor .................................................................................... 24Crankcase Emission Control ................................................................................................. 24State I/M Program Advisories Bulletins and Service Bulletins ............................................ 28

405 Module Service Help-Line Updates ........................................................................... 29

1 Title Slide (Basic Emission and Fuel System)2 Created By3 Teaching Aids4 Title Slide (Introduction) 85 Beauty Shot Impreza, Legacy, SVX 86 Title Slide (Raw Materials for Combustion) 87 Legacy Mountain Shot 88 Storage Tank 99 Atmosphere (Pie Chart) 1010 Vacuum 1011 Intake Stroke 1012 Ported Vacuum 1113 Title Slide (Combustion Process) 1114 Power Stroke 1115 Combustion Process 1116 Complete Combustion 1117 Incomplete Combustion 1218 Nitrogen During Combustion 1219 NOx Production 1220 Definitions 1221 Condition 1, Condition 2 1322 Condition 3, Condition 4 1323 Condition 5, Condition 6 1324 Catalytic Converter 1325 Normal Catalytic Operation 1326 SO2 Production 1427 Title Slide (Tumble Generator Valve) 1428 Runner Intake 1429 Stepper Motor 1430 Vent Hose 1431 TGV Sensor 1532 Manifold Bottom View 1533 TGV Passage 1534 TGV Close / Open 1535 Oxygen Sensor 1636 02 Sensor 1637 Voltage Chart 1638 AFR (Artwork) 1639 Title Slide (Closed Loop) 1740 Closed Loop 1741 Stoichiometric Window 1742 Sea Level 17

43 Title Slide (Exhaust Gas Recirculation) 1844 EGR Conventional 1845 Vacuum Diagram 1995 and Newer EGR 1846 BPT Operation, Off 1947 BPT operation, On 1948 Title Slide (Evaporative Emissions Control) 1949 Conventional Evaporative 1950 Enhanced Evaporative 2051 Canister 2052 Pressure Control Duty Solenoid 2053 Vent Control Solenoid Valve 2054 Air Filter 2155 Roll Over Valve Side In Normal Vehicle Position 2156 Roll Over Valve Side With Vehicle On Its Side 2157 Roll Over Valve Roof With Vehicle On Its Roof 2158 Title Slide (System Operation) 2259 While Driving 2260 While Refueling 2261 Title Slide (Pressure Sources Switching Operation) 2362 1995 and Newer Manifold 2363 Title Slide (Fuel Delivery Quick Connector) 2364 Quick Connector 2365 Quick Connector Service 2366 Title Slide and Artwork (ECT) (Engine Coolant Temperature Sensor) 2467 Title Slide (Crankcase Emission Control) 2468 Light Load 2469 Heavy Load 2470 Copyright71 The End

Introduction

Today's automobile is the refinement of research,which through the years has led to a computercontrolled machine sensitive to both internal andexternal influences. It is able to provide optimumperformance throughout a broad range ofatmospheric conditions, fuel quality, enginecondition and driver demand. The informationcovered in this course will get you started withthe knowledge base you must have to effectivelyanalyze conditions, situations and problemsassociated with vehicle emissions. The majorityof the course will be conducted in a lab/lectureformat.

You are required to be an active member ofthe class. Take notes and complete the labstructured work sheets. A completion test willbe given at the end of the class based oninformation covered in lecture and hands onexercises.

Raw Materials For CombustionTo fully understand the emissions produced bya vehicle, a closer look at the raw materials usedmust be made. They include fuel and theatmosphere. The fuel or gasoline is ahydrocarbon made from a mixture of componentswhich vary widely in their physical and chemicalproperties. Gasoline must cover a wide range ofvehicle operating conditions, enginetemperature, climates, altitudes and drivingpatterns.

There are many driveability conditions that canbe caused from gasoline problems. One suchproblem is incorrect fuel volatility. Volatility is afuels ability to change from a liquid to a vapor.Gasoline refiners must chemically adjust theirproduct seasonally, providing more volatilegasoline in the winter and less in the summer.There are many ways of measuring volatilityhowever there is only one practical way you cancheck it in your shop. That is the vapor pressuretest using the Reid Method.

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Problems associated with incorrect Volatility:

Low Volatility -Cold Start

Warm up performance

Cool weather performance

Cool weather drive ability

Increased deposits of the combustionchamber

High Volatility -High evap emissions

Hot drive ability

Vapor lock

Poor fuel mileage

There are six volatility classes of gasoline.Record their values on the spaces below.

AA

A

B

C

D

E

Higher volatile fuels will evaporate easier thanlower volatile fuels so higher pressure readingswill be achieved.

Storage Tank

Phase SeparationAnother problem of today's' gasoline can becreated if the fuel is stored in a watercontaminated tank. Referred to as Phaseseparation, this condition results because of theuse of alcohols as octane boosters andoxygenates. The alcohol in the gasoline willabsorb the water in the tank and separate fromthe gasoline. This new heavier mixture will settlein the bottom of the storage tank. Sooner or latersomeone will get a tank full or enough of itpumped into their vehicle to cause a drive abilityproblem. Oxygenates or alcohols are used infuels where lower emission output is required bystate or federal regulations. These fuels arecalled "Reformulated" or "Oxygenated" fuel. Thedifference between the two is the amount ofadditional oxygen they supply to the combustionprocess.

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Reformulated and Oxygenated Fuel"Reformulated" fuel contains 2% oxygen byweight. "Oxygenated" fuel contains 3.5% oxygenby weight. There is a trade off with use of eitherof these fuels and that is a 2% fuel economy lossand less energy output per gallon. Gasolinenormally creates 115,000 BTU's per gallon.Reformulated or Oxygenated fuel will produceonly 76,000 BTU's per gallon. Ethanol andMethanol are the two alcohols used inoxygenated gasoline. Methanol is a woodalcohol and can be used up to 5% with most automanufactures. However it is very corrosive andmany cosolvents and rust inhibitors must be usedwith it to prevent damage to the fuel system.Ethanol or grain alcohol is not as corrosive andis allowed up to 10%.

OctaneOctane is defined as a fuels ability to resist knock.Also known as the Anti Knock Index. (AKI) is theaverage of the Motor and Research OctaneNumber (RON).

(R+M)/2 Laboratory tests determine MON andRON. There is no advantage in using a higheroctane than it takes to prevent engine knock.Engine knock is created by using a lower octanethan is required. Heat and pressure will ignitethe air fuel mixture before the spark, creating anuneven burn across the combustion chamber.Subaru ignition timing learning control logicmemorizes when the engine knock occurs, andretards the timing away from optimum tocompensate.

Atmosphere

Atmosphere

The atmosphere is composed of 79% nitrogen,20% oxygen and 1% inert gases.

Each intake stroke fills the cylinder with thesegases. This action also produces vacuum.

Vacuum

Manifold Vacuum

There are two types of vacuum or negativepressure produced by the engine. The first to beproduced in a measurable amount is calledIntake manifold vacuum. It is produced by theintake stroke of the engine.

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The second type is Ported vacuum. It is producedby the volume and speed of the air entering theengine. The positioning of the throttle platedetermines the amount produced and at whatspot in the throttle bore it is located. This effectenables the ported vacuum to be used as aworking pressure and a controlling pressure.

Ported Vacuum

Combustion ProcessCombining fuel and atmosphere in thecombustion chamber under pressure andsupplying a spark changes chemical energy toheat energy. The resulting gas expansionpushes the piston down.

Power Stroke

Combustion splits gasoline or HC. Enginetemperature, compression, fuel purity, ignitiontiming, and the mechanical condition of theengine determine the degree of completecombustion. This ultimately determines theamount and type of exhaust emissions produced.Near complete combustion will join oxygen withhydrogen and form water. The carbon will joinwith oxygen to form CO2, Carbon Dioxide.

Combustion Process

Complete combustion is very hard to achievebecause of uneven engine temperatures,random fuel impurities and many othersituations, however in theory if completecombustion did take place one gallon of gasolinewould produce one gallon of water.

Complete Combustion

Incomplete combustion occurs when the entirefuel charge is not burned in the combustionchamber. Unburned HC will be exhausted to theatmosphere if the exhaust remains untreatedCarbon will still join with oxygen but with onlyone part so the result is the production of CarbonMonoxide, CO. This gas is very unstable. Ifinhaled .3 of 1% in a 30 minute time frame willcreate Carbon Monoxide Poisoning which canbe fatal. HC and CO are both harmful to theatmosphere.

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Incomplete Combustion

Another harmful gas is oxides of nitrogen, NOx.The x is an indicator that the number of oxygenmolecules is unknown. NOx is produced fromhigh pressure and heat in excess of 2500° F(1371.1 C) in the combustion chamber.

Nitrogen During Combustion

NOX Production

Notes:

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Review the analyzer readings below and choosethe correct answer that best describes thecondition. (Write the corresponding letter on thespace provided below).

A) Normal Condition E) Loose Knock Sensor

B) Rich F) Open Coolant Temp Sensor

C) Lean G) Clogged Injector

D) Lean Misfire H) Open Plug Wire

Condition 1:

Condition 2:

Condition 3:

Condition 4:

Condition 5:

Condition 6:

Catalytic ConverterReducing HC, CO and NOx is the objective ofthe catalytic converter. The converter is made ofa honey comb ceramic structure held in placewith a Nickel support shell all contained in ametal housing. Rare nobel metals, Platinum,Palladium and Rhodium, are adhered to theceramic structure. These two metals give thecatalytic converter a 3 way operatingcharacteristic. When in operation the converterwill change CO, HC and N0x to CO2, Nitrogenalso enables it to store oxygen during times of alean mixture and bring it into the conversionprocess during times of ric mixtures. Anoperating temperature of at least 600° F (315.55C) is required for the catalytic converter tooperate.

Normal Catalytic Operation

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The Nickel content of Catalytic converts has beenreduced in recent years because of its naturalability as a reducing agent.

SO2 Production

This characteristic normally is beneficial to thereduction of harmful emissions but if the fuel issulfur contaminated the results is the productionof Hydrogen Sulfide, H2S. Federal regulationsstate that there can only be 1/10 of 1% sulfurcontent in fuel. Removing sulfur from crude oil isan expensive and difficult procedure sometimesyielding poor results. Sulfur content higher thanthe Federal specification creates the sulfurcontaminated fuel. Initial combustion of thecontaminated fuel produces SO2. SO2 burnedin the catalytic converter creates SO3. SO3absorbs water very easy and produces H2SO4.

Some of the SO2 created at combustion will flowacross the Nickel which strips or reduces anoxygen molecule from it and a Hydrogenmolecule will replace it. Yielding H2S thearomatic that smells like rotten eggs.

Tumble Generator Valve

Runner Intake

Stepper Motor

The EJ-2.0 is equipped with a tumble generatorvalve at each intake runner. This new systemuses a shaft for each side of the engine that isdriven by a stepper motor. The movement of theshaft is monitored by a sensor on the oppositeend.

Vent Hose

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TGV Sensor

The shaft operates the tumble generator valve,which is a plate similar in design to the throttleplate. At idle the plate is closed (dependant oncoolant temperature and time from engine start).

Off idle the plate is open.

Manifold Bottom View

TGV Passage

When the plate is closed the main air passagethrough the intake runner is blocked. This willforce all air necessary for engine operation duringidle to flow through the bypass channel. Thisaction helps to mix the air fuel mixture byproducing a tumbling effect to the incoming air,resulting in a cleaner operating engine whileidling.

TGV Close / Open

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Oxygen SensorsOxygen sensors function to determine theamount of oxygen in the exhaust. The sensor islocated upstream of the catalytic converter andmonitors the exhaust as it leaves the engine. Richair fuel mixtures will have very little oxygen inthe exhaust while lean mixtures have much moreby comparison.

O2 Sensor

The oxygen sensor after reaching an operatingtemperature of 600° F (315.55 C) compares theoxygen content of the atmosphere to the oxygencontent of the exhaust. Materials making up theoxygen sensor generate a small voltage thatrepresents the air fuel mixture. This electricalsignal is sent to the ECM so that adjustments canbe made reducing harmful HC emissions. Richair fuel mixtures generate higher voltages nohigher than 1 volt and lean air fuel mixturesgenerate lower voltages closer to 300 millivolts.

Voltage Chart(Oxygen Sensor Operation)

The normal color of the oxygen sensor tip is gray.White indicates the sensor has been operatingin a constant lean air fuel mixture. Blackindicates a constant rich air fuel mixture.Diagnose the fuel and engine managementsystem if the color of the sensor is other than grey,as the response time or sensitivity of the sensorhas been affected.

The Air Fuel Ratio Sensor is used on 1999California Models. Located in place of the frontOxygen Sensor, the AFR begins to operate andeffect the Air Fuel Ratio faster than conventionalOxygen Sensors. Zirconia remains the keymaterial in AFR construction. It’s ability to absorboxygen and new ECM circuitry work together toprovide fast accurate data.

A contact plate is located on the top and bottomof a layer of Zirconia. These plates are connectedto wires that lead to the ECM. The exhaust sideof the AFR is covered by a porous chamber thatallows the exhaust gas access to the Zirconiacenter while the outside of the AFR sensor isexposed to the atmosphere.

Oxygen ions pass from the exhaust side to theatmospheric side during lean engine operationand from the atmospheric side to the exhaust sideduring rich engine operation. Stoichiometricengine operation will result in no ion exchange.

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Closed Loop

Closed Loop

Closed loop is a description of fuel injection andengine management operation where bothsystems are monitored and adjusted.

Closed loop relies on input from sensors thatmonitor engine operation. Providing precisecontrol to increase power and reduce emissions.

Open loop is a description of the fuel injectionand engine management systems that providethe best operating conditions during: Cold engineoperation, near full throttle, and fail-safe.

Stoichiometric Window

Maintaining the ideal air fuel mixture that createsthe most power and lowest emissions is referredto as Stoichiometric. At sea level the weight ofthe atmosphere is 14.7 pounds per square inch.This column of air extends from the ground toapprox. 110 miles straight up. This 14.7 psiburned with 1 pound of fuel is stoichiometric.Higher altitudes have less dense air, it weighsless because its closer to the beginning of the110 mile high column.

Sea Level(Atmospheric Pressure)

Maintaining stoichiometric air fuel mixture in thiscondition becomes more difficult. Theatmospheric pressure can be increased in theengine with turbo chargers and super chargers.The introduction of additional air to the air fuelmixture will compensate for the less dense air.

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Exhaust Gas Recirculation

Exhaust Gas Recirculation

Preventing the production of harmful emissionsis the best way to keep them from the atmosphere.NOx emissions control is performed by theExhaust Gas Recirculation (EGR) system. TheEGR system when activated displaces 6 to 13% of the normal air in the intake manifold. Part ofthe exhaust is routed through the EGR valve tothe intake manifold. This EGR gas has alreadyburned, containing little oxygen and fuel. Mixedin the combustion chamber with normal air andfuel, the EGR gas reduces the heat because theEGR gas will not effectively burn. The heatgenerated with normal air surrounding the EGRgas is absorbed by the EGR gas and exits theengine as exhaust. This action lowers the overallcombustion chamber temperature controlling theproduction of NOx emissions.

The EGR valve is operated with a ported vacuumsignal that is controlled by the EGR solenoid.Solenoid activation is dependent on ECM logic.

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EGR systems used on later model Subaruvehicles are controlled with a solenoid and aBack Pressure Transducer (BPT). Portedvacuum enters the BPT at line R, this will beused as working pressure. Ported vacuum entersthe BPT at line P, this will be used as controlpressure, throttling vacuum in line R to line Q.Exhaust enters the bottom of the BPT pushingthe diaphragm assisting the pressure at line P.

This action continues during all engineoperation, however the EGR valve will notoperate until the ECM grounds the EGRsolenoid.

Vacuum DiagramMost 95 and Newer EGR

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BPT OperationEGR Off

BPT OperationEGR On

Evaporative Emissions ControlSubaru vehicles are equipped with either aConventional or Enhanced EvaporativeEmissions Control System. Both systemsfunction to prevent unburned Hydrocarbons fromescaping to the atmosphere.

Conventional Evaporative System

Conventional Evaporative components includethe following:1. Fuel Cap - Construction incorporates a relief

valve that allows air to enter the tank in theevent a vacuum develops.

2. Canister - Temporarily stores evaporative gasfrom the fuel tank.

3. Purge control Solenoid valve - Controls theflow of stored evaporative gas from the

canister to the intake manifold.4. Two way valve - Controls air flow to the fuel

tank. High tank pressure opens the valveallowing the pressure and evaporative gasto the canister. Low tank pressure closes thevalve allowing atmosphere to the fuel tankthrough a pinhole in the valve.

5. Fuel cut valve - Used on AWD models.Prevents liquid fuel from entering theevaporative line.

Fuel separator allows fuel vapor to condenseand return to the tank as liquid. Some modelsuse a plastic tank mounted in the trunk or cargoareas. Other models use an air space designedinto the fuel tank to condense fuel vapors.

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System operation - The ECM grounds the purgecontrol solenoid turning it on. Ported vacuumthen removes the stored evaporative gas fromthe canister. System activation is controlled usingcoolant temperature engine load and vehiclespeed input.

Enhanced Evaporative System

Enhanced Evaporative components include:1. Canister - Function is unchanged, however

the shape is more boxy and is located underthe right rear of the vehicle.

Canister

2. Pressure control duty solenoid - Adjusts thepressure inside the fuel tank from a signalfrom the ECM. It also controls the flow ofevaporative gas from the fuel tank to thecanister.

Pressure Control Duty Solenoid

3. Vent Control Solenoid Valve - Controls theflow of atmospheric pressure to the canister.During normal operation the valve is openallowing atmospheric pressure to thecanister. During the time the ECM is checkingthe integrity of the evaporative system thevalve is closed to isolate the system fromatmosphere.

Vent Control Solenoid Valve

4. Air Filter - Filters air as it enters the ventcontrol solenoid valve.

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Air Filter

5. Fuel Tank Pressure Sensor - Monitors fueltank pressure and sends an input signal tothe ECM.

System operation - Optimum purge control isprogrammed in the ECM and is influenced byengine load, coolant temperature and vehiclespeed.

Low fuel tank pressure - Pressure controlsolenoid valve closed. Vent control solenoidopen. Purge Control Duty Solenoid active.

High fuel tank pressure - Pressure controlsolenoid valve open.

Fuel caps of both systems have a vacuum reliefvalve that allows atmospheric pressure to enterthe fuel tank. This prevents vacuum from formingas the fuel is used, and acts as a back up for thetwo way valve.

Roll Over Valve In Normal Vehicle Position

Both systems use a rollover valve located underthe center rear of the vehicle. Rollover valveoperation prevents fuel from flowing through theevaporative line in event of vehicle rollover.Valve operation is performed by gravity and theposition of two "Ball Valves".

Roll Over Valve WithVehicle On Its Side

Roll Over Valve WithVehicle On Its Roof

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On Board Refueling Vapor RecoveryThis system will be used on all 2.2 liter Legacyand Impreza vehicles. Forester will be equippedwith ORVR beginning approximately withOctober production.

ORVR controls the pressure inside the fuel tankand collects fuels vapors during all vehicleoperating conditions and during the time thevehicle 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 vaporsduring the time the vehicle is being refueled.

• Pressure difference detecting line-Directsatmospheric pressure

• to the back side of the valve vent diaphragm.

• Orifice chamber - Drains fuel from thepressure difference detecting line into thetank.

• Shut valve - Closes the evaporation linewhen a filler gun is inserted into the filler neck.Prevents fuel vapors from escaping toatmosphere while refueling.

• Tank pressure sensor - Monitors fuel tankpressure for diagnosis.

• Vent line - Directs fuel vapors from the valvevent to the cannister during the time thevehicle is being refueled.

• PCV (Pressure Control Valve)-Controls theflow of fuel vapors from the tank to thecannister except during the time the vehicleis being refueled. And controls the flow ofatmospheric pressure to the tank when anegative pressure develops.

• Drain Valve - Provides a pathway toatmosphere for air after the fuel vapors havebeen removed by the charcoal element of thecannister. (Only during the time the vehicleis being refueled.)

System OperationWhile driving

ORVR System

The fuel tank pressure is applied to one side ofdiaphragm inside the Pressure Control Valve.

When the pressure is greater than atmospherica port inside the PCV opens allowing fuel vaporsto the cannister.

If negative pressure exists the PCV opensallowing atmospheric pressure to the fuel tank.

While refuelingAs fuel fills the tank the air inside the tank isdisplaced caring fuel vapors with it. This largeincrease in pressure opens the valve ventallowing the fuel vapors to the cannister.

The continued filling of the tank pushes theremaining air and fuel vapors through thecannister. The charcoal element of the cannisterabsorbs the fuel vapors an directs fuel vapor freeair to the atmosphere though the Drain valve andair filter.

While Refueling

The PCV is checked for circuit malfunction. Drainvalve checks include circuit and performancechecks.

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Pressure Sources SwitchingOperation

1995 and Newer Manifold

Pressure sources switching solenoid (PSSS)Used on 1995 and newer vehicles equippedwith OBDII. Functions from an ECM groundsignal and Switches to allow atmosphericpressure to the pressure sensor during enginestart and every 30 minutes, or 3.1 miles (5kilometers). Switches to allow manifold pressuresensor when not switched to atmosphere.

The passage way to atmosphere onConventional evaporative systems accessatmosphere through the evaporative canister.Enhanced evaporative systems accessatmosphere through an extension of the PSSS.

The Pressure sensor Functions to monitormanifold and atmospheric pressure. PSSSposition determines pressure source. Changesin pressure positive or negative produce achanging reference voltage signal. Referencevoltage signal changes are used to influenceignition timing and injection duration.

Canister purge flow is also monitored with thePressure Sensor. (PSSS switches to atmospherewhile the purge control solenoid is on)

Fuel Delivery Quick ConnectorThe fuel system of the forester is very similar topast models with enhancements to tankcapacity, clamps, and delivery line. The resindelivery line between the fuel pump and the 60liter fuel tank are connected by a one time useonly “Quick Connector”.

This “Quick Connector” must be released whenremoving the fuel pump or fuel tank.

Quick Connector

Quick connector service procedure.1. Separation - Pushing the retainer with a finger

in the arrow direction, pull the connector toseparate it. After separation, the retainer willremain attached to the pipe.

2. Connecting- Check the connecting portion ofthe pipe visually. If a scratch or foreign particleexists on it wipe them off.

Align the pipe and the connector, insert the endof the pipe into the connector until an audibleclick is heard.

Confirm connection by pulling the connectorbackward. Also check that the two pawls of theretainer are engaged to the connector.

Replacement part is the retainer only.

Quick Connector Service

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Engine Coolant TemperatureSensor

ECT

Engine Coolant Temperature Sensor (ECT)functions to monitor coolant temperature.Resistance of the sensor with cold coolant ishigh. Reference voltage from the sensor will below Resistance of the sensor with warmer coolantis low. Reference voltage will be higher.Reference voltage signal changes are used toinfluence ignition timing, injection duration, andidle speed. Some models use ECT signal tocontrol radiator fan motor relays. Fail-safe onthese models will result in constant radiator fanoperation.

Crankcase Emission ControlCrankcase Emission Control System Functionsto prevent blow-by gases from entering theatmosphere. Components include: Sealedrocker covers, hoses, PCV valve and Air intakeduct.

Operation is performed in two modes:Mode one - (Light engine load) Air flows in tothe air duct, and part of the air is routed to therocker covers. Vapors and air enter the PCVbecause of the negative pressure at thevalve.

Mode two - (Heavy engine load) Air flows into the air duct, and produces a negativepressure at the rocker covers. This actioncarries the vapors from the crankcase into thethrottle body.

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Notes:

Notes:

Notes:

State I/M Program Advisories Bulletins and Service BulletinsNo. Date Title Subject

11-50-97 12/05/97 All Subaru Full-Time AWD Models State Emission Testing11-51-97 12/05/97 All Subaru Full-Time AWD Models Diagnostic Service Cautions11-52-98 05/22/98 All 1999 Model Subaru AWD Models State Emission Testing11-49-97R 09/02/98 1996 MY Legacy, Impreza & SVX OBD Check During State I/M Program11-53-98 01/05/99 97-98 Legacy, Impreza and Forester

Manual Transmission vehicles with2.5L & 2.2L engines Hesitation On Acceleration

11-54-99 03/01/99 All 1996-1999MY On-Board Diagnostic SystemDiagnostic Link Connector (DLC)Location

11-55-99 03/17/99 All 1996-2000MY On-Board Diagnostic SystemCheck During State Emission Test

11-56-99 09/08/99 All 2000MY State Emission Testing11-57-99 09/29/99 All 2000 MY On-Board Diagnostic System

Diagnostic Link Connector (DLC)Location

11-59-00 02/25/00 1999 Legacy, Impreza, Forester Air Intake Chamber Box Breakage11-61-00 06/01/00 All Subaru Vehicles State Emission Test / Fuel Filter or

Gas Cap Test11-62-00 05/08/00 All 2001 Models Subaru Vehicles On-Board Diagnostic System

Check During State Emission Test11-63-00 11/01/00 1980-1989 MY Subaru Vehicles Pressure Testing of Fuel Tank System

During State Emission Test11-64-01 02/01/01 All 1996-1999 Legacy Postal Vehicles On-Board Diagnostic System

Diagnostic Link Connector (DLC)Location

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Subaru of America, Inc.