2-7 SVX T+~++ FUEL INJECTION SYSTEM SUBARU

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1 FUEL NJECTON SYSTEM SUBARU SVX 1992 Precaution for Supplemental Restraint System "Airbag" The Supplemental Restraint System "Airbag" helps to reduce the risk or severity of injury to the driver in a frontal collision. The Supplemental Restraint System consists of an airbag module (located in the center of the steering wheel), sensors, a control unit, warning light, wiring harness and spiral cable. nformation necessary to service the safety is included in the "5-5. SUPPLEMENTAL RE- STRANT SYSTEM" of this Service Manual. WARNNG : To avoid rendering the Airbag system inoperative, which could lead to personal injury or death in the event of a severe frontal collision, all maintenance must be performed by an authorized SVX dealer. mproper maintenance, including incorrect removal and installation of the Airbag system, can lead to personal injury caused by unintentional activation of the Airbag system. All Airbag system electrical wiring harnesses and connectors are covered with yellow outer insulation. Do not use electrical test equipment on any circuit related to the Supplemental Restraint System "Airbag" M MECHANSM AND FUNCTON , 1. General , 2. Air Line Fuel Line nduction Control System , 5. Sensor and Switch Control System Self-diagnosis System C COMPONENT PARTS ntake Manifold and Collector Air ntake Boot and Throttle Body Air Cleaner T TROUBLESHOOTNG. e Supplemental Restraint System "Airbag" Precautions Pre-inspection Electric Unit Location Troubleshooting Chart for Self-diagnosis System Output Modes of Select Monitor Control Unit /O Signal Troubleshooting for Engine Starting Failure Troubleshooting Chart with Trouble Code Troubleshooting Chart with Select Monitor General Troubleshooting Table T+~++

2 2-7 [M1ool FUEL NJECTON SYSTEM M MECHANSM AND FUNCTON 1. General The Multi Point Fuel njection (MPF) system is a system that supplies the optimum air-fuel mixture to the engine for all the various operating conditions through the use of the latest electronic technology. With this system fuel, which is pressurized at a constant pressure, is injected into the intake air passage of the cylinder head. The injection quantity of fuel is controlled by an intermittent injection system where the electromagnetic injection valve (fuel injector) opens only for a short period of time, depending on the quantity of air required for one cycle of operation. n actual operation, the injection quantity is determined by the duration of an electric pulse applied to the fuel injector and this permits simple, yet highly precise metering of the fuel. Further, all the operating conditions of the engine are converted into electric signals, and this results in additional features of the system, such as large improved adaptability, easier addition of compensating element, etc. The MPF system also has the following features : 1) Reduced emission of harmful exhaust gases. 2) Reduced in fuel consumption. 3) ncreased engine output. 4) Superior acceleration and deceleration. 5) Superior startability and warm-up performance in cold weather since compensation is made for coolant and intake air temperature. 2

3 FUEL NJECTON SYSTEM [M100] Radiator main fan 2 Radiator sub fan 3 A/C compressor 4 nhibitor switch 5 Vehicle speed sensor 2 6 Speedometer 7 CHECK ENGNE - light 8 Tachometer 9 Resistor 10 Fuel pump modulator 11 Roll over valve 12 Purge control solenoid valve 13 Canister 14 Throttle sensor 15 Auxiliary air control valve 16 By-pass air control solenoid valve 17 Throttle cable 18 Cruise control cable 19 Air flow sensor 20 Fuel filter 21 Fuel pump 22 nduction valve diaphragm 23 nduction control valve 24 PCV valve 25 One way valve 26 Vacuum tank 27 nduction control solenoid valve 28 Puressure regulator 29 Fuel injector 30 Knock sensor 1 (RH) 31 Crank angle sensor 2 32 Water temperature sensor 33 Knock sensor 2 (LH) 34 gniter 35 gnition coil. 36 Cam angle sensor 37 Crank angle sensor 1 38 Spark plug 39 EGR solenoid valve 40 BPT 41 EGR valve 42 Recirculation gas temperature sensor (Col. only) 43 Oz sensor 1 (RH) sensor 2 (LH) ZCASE ON ROLSYSTEM O FS 1 1 G (D C

4 2-7 [M201 FUEL NJECTON SYSTEM 2. Air Line 1. GENERAL Air which is drawn in and filtered by the air cleaner is metered and sent to throttle body via the air intake boot. From the throttle body, the air is regulated by the open-close operation of the throttle valve and is delivered to the collector chamber and the intake manifold. t is then distributed to the respective cylinders to mix with fuel injected by the fuel injectors. Thus, the air-fuel mixture is delivered into the cylinder. Part of the air branched at the upstream of the throttle body is sent to the by-pass air control solenoid valve which regulates engine idle speed. Air cleaner ~--~{ Air flow sensor ~~J Throttle body f,,~~ Collector chamber ~~J ntake manifold By-pass air control solenoid J Fuel injector valve Auxiliary air control valve Cylinder 2. AR FLOW SENSOR The MPF system employs a hot-film type air flow sensor. This air flow sensor converts the amount of intake air into an electric signal by utilizing the heat transfer phenomenon between the incoming air and heating resistor located in the air intake. The features of this air flow sensor type are as follows : 1) High-altitude compensation is automatically made. 2) Quick response. 3) There are no moving parts. 4) t is compact. Fig. 2 Air Flow -Hot film ~r~. ~ FLOW a Hot wire C

5 FUEL NJECTON SYSTEM M2o THROTTLE BODY n response to the depressing stroke of the throttle pedal, the throttle body opens/closes its valve to regulate the air volume to be taken in the combustion chamber. During idling, the throttle valve is almost fully closed and the air flow through the throttle body is less than that passing through the carburetor. More than half of the air necessary for idling is supplied to the intake manifold via the by-pass air control solenoid valve. And the by-pass air control solenoid valve properly controls the number of revolutions in idling, so it does not need to be adjusted. 4. THROTTLE SENSOR This throttle sensor is provided with a potentiometer. The throttle sensor converts the opening of the throttle valve into an electric signal, and sends it to the ECU. Using this signal, the ECU precisely controls the air-fuel ratio during acceleration and deceleration as well as idling. 5. BY-PASS AR CONTROL SOLENOD VALVE The ECU controls the duty control valve in the by-pass air control solenoid valve to bring the operating engine speed as close to preset idle speed as possible. 6. AUXLARY AR CONTROL VALVE Auxiliary air control valve consists of a bimetal, coil heater and rotary valve. This valve supplies by-pass air only when engine is cooled. Fig. 4 AR N Rotary valve. AR OUT 0 Valve fulcrum o o ' Bimetal L Coil heater C COLLECTOR The collector is the passage for distributing the intake air into each cylinder. t has the induction control valve built in, and the air-induction is controlled by its operation. Solenoid Connector Air nlet Duty control valve Fig. 3 C

6 2-7 (M3001 FUEL NJECTON SYSTEM 3. Fuel Line level by the pressure regulator on the way to the injectors. 1. GENERAL From the injectors, fuel is injected into the intake man- Fuel pressurized by the fuel pump built into the fuel tank ifold where it is mixed with intake air, and is then is delivered to fuel injectors by way of the fuel pipe and delivered to the respective cylinders. fuel filter. Fuel is regulated to the optimum pressure Fuel injection timing and the amount of fuel injected is regulated by the ECU. F Fuel tank (Fuel)- - Fuel pump Fuel filter Fuel injector Pressure regulator Cylinder ECU purge control solenoid valve Throttle body -D = #6 Pressure regulator Collector J #4 #3 Fuel filter #2 #1 1 1 Delivery line Fuel cut valve Fuel injector Return line Evaporation line Canister Roll over valve Fuel tank Jet pump Fuel pump C2-017 Fig. 5 6

7 FUEL NJECTON SYSTEM [M303] PRESSURE REGULATOR The pressure regulator is divided into the fuel chamber and the spring chamber by the diaphragm as illustrated below. Fuel is fed to the fuel chamber through the fuel inlet connected with the injector. A difference in pressure between the fuel chamber and the spring chamber connected with the intake manifold causes the diaphragm to be pushed down, and fuel is fed back to the fuel tank through the return line. By returning fuel so as to balance the above pressure difference and the spring force, the fuel pressure is kept at a constant level kpa (2.55 kg/cmz, 36.3 psi) against the intake manifold pressure. To intake manifold Valve Diaphragm From fuel injector a 3. FUEL NJECTOR The MPF system employs a gallery type (side-feed type) fuel injector. The gallery type fuel injector is installed in the fuel pipe to allow cooling of the injector by the fuel. The features of this type of fuel injector are as follows : 1) High heat resistance 2) Low driving noise 3) Easy to service 4) Small size The fuel injector injects fuel according to the valve open signal received from the ECU. The nozzle is attached on the top of the fuel injector. The needle valve is lifted by the solenoid coil through the plunger on arrival of the valve open signal. Since the injector opening, the lifted level of valve and the regulator-controlled fuel pressure are kept constant, the amount of fuel to be injected can be controlled only by the valve open signal from the ECU. To fuel tank B2-284 Fig. 6 Fig. 7 7

8 2-7 [M4001 FUEL NJECTON SYSTEM 4. nd uction Control System according to engine operation, thereby increasing the amount of air introduced in the cylinders. 1. GENERAL This increase in the amount of air is generally referred to The induction control system opens and closes the as the "high" charging efficiency. induction control valve to change the intake air flowrate Pressure vibration in collector 1 00 A- --A : Close 0----o : Open ae 90 > > t( U C-7 --yam w d U 80, \ \~ b 2 70 O J Engine speed (rpm) ntake valve Open ~ Open ~F Open timin g Pressure + in collector ~ ~-~ -` Pressure just i n front of intake valve + 0 Fig. 8 C

9 FUEL NJECTON SYSTEM M4o On low engine speed On high engine speed nduction control valve "CLOSE" nduction control valve "OPEN" Fig CONTROL FUNCTON The induction control valve operates on the intake manifold pressure transmitted to the diaphragm. The intake manifold pressure is controlled by opening/ closing the induction solenoid valve which is determined by the ECU according to the engine speed and fuel injection quantity. [msl o m 0 4,200 ON i OFF (Close) ~~ (Open) ~~ Y ON --- C2-167 OFF OFF (Open) Fig. 10 Engine Speed [rpm] C

10 2-7 [M500] FUEL NJECTON SYSTEM 5. Sensor and Switch SENSOR The OZ sensor is used to sense oxygen concentration in the exhaust gas. f the fuel ratio is leaner than the stoichiometric ratio in the mixture (i.e. excessive amount of air), the exhaust gas contains more oxygen. To the contrary, if the fuel ratio is richer than the stoichiometric ratio, the exhaust gas contains hardly any oxygen. Therefore, examination of the oxygen concentration in exhaust gas makes it possible to show whether the air/fuel ratio is leaner or richer than the stoichiometric ratio. The Oz sensor has a zirconia tube (ceramic) which generates voltage if there is a difference in oxygen concentration between the inside and outside of the tube. Platinum is coated on the inside and outside of the zirconia tube for the purpose of catalysis and electrode provision. The hexagon screw on the outside is grounded to the exhaust pipe, and the inside is connected to the ECU through the harness. A ceramic heater is employed to improve performance at low temperature. When rich air-fuel mixture is burnt in the cylinder, the oxygen in the exhaust gases reacts almost completely through the catalytic action of the platinum coating on the surface of the zirconia tube. This results is a very large difference in the oxygen concentration between the inside and outside, and the electromotive force generated is large. When a lean air-fuel mixture is burnt in the cylinder, oxygen remains in the exhaust gases even after the catalytic action, and this results in a small difference in the oxygen concentration. The electromotive force is very small. The difference in oxygen concentration changes greatly in the vicinity of the optimum air-fuel ratio, and hence the change in the electromotive force is also large. By inputting this information into the MPF control unit, the air-fuel ratio of the supplied mixture can be determined easily. The Oz sensor does not generate much electromotive force when the temperature is low. The characteristics of the electromotive force stabilize at temperature of approximately 300 to 400 C (572 to 752 F). Electromotive y force Exhaust gases large Atmosphere V ~ ( U Theoretical air-fuel ratio 0 (Rich signal) To be judged as rich f Exhaust gases Comparison voltage 0 0 o To be judged Ti x as lean m wo! (Lean signal) Small Air-fuel Large Small ratio Fig. 11 B Fig. 12 B WATER TEMPERATURE SENSOR The water temperature sensor is located on the water pipe which is made of aluminum alloy. ts thermistor changes resistance with respect to temperature. A water temperature signal converted into resistance is transmitted to the ECU to control the amount of fuel injection, ignition timing, purge control solenoid valve, etc. Fig. 13 Y 2.5 u c m 20 C 168 F) 2.5 kn (-4) (32) (104) (176) (68) (140) Temp. C ( F) B2-288

11 FUEL NJECTON SYSTEM [M Connector Thermistor element 4. CRANK ANGLE SENSOR 1 The crank angle sensor is installed on the oil pump, located in the front center portion of the cylinder block, to detect the crank angle position. t is designed so that the ECU accurately reads the number of pulses which occur when protrusions provided at the perimeter of the crank sprocket (rotating together with the crankshaft) cross the crank angle sensor. The crank angle sensor is a molded type which consists of a magnet, pick-ups, coil, terminals, etc. Mold Fig. 14 B KNOCK SENSOR The knock sensor is installed on the cylinder block, and senses knocking signals from each cylinder. This knock sensor is a piezo-electric type which converts knocking vibrations into electric signals. t consists of a piezo-electric element, weight, and case. f knocking occurs in the engine, the weight in the case moves causing the piezo-electric element to generate a voltage. Terminal ASSY O-ring \\\\ li Pickup Coil ~ Magnet Case\ Pickup Terminal, Molded tape Bobbin nsulator Fig. 16 B2-291 Housing '--' _Weight Resistor Piezo element- Connector Function The crank sprocket which is used with crank angle sensor 1, is provided with twelve protrusions. Crank rotation causes these protrusions to cross crank angle sensor 1 so that magnetic fluxes in the coil change with the change in air gap between the sensor pickup and the sprocket. The change in air gap induces an electromotive force which is transmitted to ECU. ECU detects every 30 of the crank angle. Fig. 15 B2-290 Fig. 17 C

12 2-7 [M505] FUEL NJECTON SYSTEM 5. CRANK ANGLE SENSOR 2 The crank sprocket which is used for crank angle sensor 2, is provided with six protrusions. As the crank sprocket rotates as crank shaft the ECU detects that each cylinder is divided into two grounds the #3-#2- #5, #4-#1-#6). O " 1 SS 6. CAM ANGLE SENSOR Cam angle sensor is located on the left-hand camshaft support. The back of LH cam sprocket is provided with one protrusion. As the cam shaft sprocket rotates a half crank sprocket speed, cam angle sensor emits a signal to the ECU whenever engine rotates two revolutions. The ECU detects the compression top dead center of each cylinder with the crank angle sensor 2 signal which is accompanied with the cam angle sensor signal. Cam angle sensor Air gap Projection - Projection GROUP i~ O C2-170 Fig. 18 QCam sprocket C2-171 Fig HOW TO DETECT EACH CYLNDER The crank angle sensor 2 issues signals in the order of 3-pitches, 2-pitches, and 1-pitch, and the cam angle sensor issues one signal for every two crankshaft rota- tions. Then, the ECU knows which cylinder will reach the compression top dead center next according to the combination of the signals issued from both sensors. Signal Cylinder No. #1 #6 #3 t! 2 #5 M Crank angle sensor 2 Cam angle sensor Cylinder 3 pitches #3 2 pitches 0 #2 Crank 1 / / 1 / / / signal 2 v U~ ~~ U~ ~ V\ 1 pitch #5 Cam signal '. ' 3 pitches #4 2 pitches x #1 1 pitch #6 Fig. 20 C

13 FUEL NJECTON SYSTEM [M602] Control System 1. GENERAL The ECU receives signals sent from various sensors and switches to judge the engine operating condition and emits output signals to provide the optimum control and/or functioning of various systems. Major items governed by the ECU are as follow : 2. NPUT AND OUTPUT SGNALS Fuel injection control gnition system control By-pass air control EGR control Canister purge control Radiator fan control Engine torque control Air conditioner cut control Self-diagnosis function Unit Function Air flow sensor Detects amount of intake air. Throttle sensor Detects throttle position. OZ sensor 1 OZ sensor 2 Detects the density of OZ in exhaust gases. Crank angle sensor 1 Detects engine speed. Crank angle sensor 2 Cam angle sensor Detects the relative cylinder position. npu t s igna l Water temperature sensor Detects coolant temperature. Knock sensor 1 Detects engine knocking for all cylinders. Knock sensor 2 Vehicle speed sensor Detects vehicle speed. Atmospheric pressure sensor Detects atmospheric pressure. gnition switch Detects ignition switch operation. Starter switch Detects the condition of engine cranking. nhibitor switch Detects shift position. A/C switch Detects ON-OFF operation of A/C switch.. Fuel injector nject fuel. gnition signal Turn primary ignition current ON or OFF. Fuel pump relay Turn fuel pump relay ON or OFF. A/C control relay Turn A/C control relay ON or OFF Output s igna l Radiator fan control relay Turns radiator fan control relay ON or OFF. nduction control solenoid valve Controls nduction control valve. By-pass air control solenoid valve Adjusts amount of by-pass air through throttle valve. EGR solenoid valve Controls EGR valve. Purge control solenoid valve Controls canister purge control solenoid valve. ( HECK ENGNE light ndicates trouble. 13

14 2-7 [M6031 FUEL NJECTON SYSTEM 3. FUEL NJECTON CONTROL ECU receives signals emitted from various sensors to control the amount of fuel injected and the fuel injection timing. Sequential fuel injection control is utilized over the entire engine operating range except during standing starts. As for injection timing, the ECU controls the starting of injection with leading to the signal emitted from crank angle sensor 1. The starting of injection is changed between BTDC 50 (deg) and BTDC 10 (deg) under various conditions. STDC sensor # #3 ~ 30 ~ ~ 700 i i ~ ~ #2 #5 04 ~ ', i Crank angle sensor 2 am angle sensor t 1, #5 Air intake timing ntake valve timing Open 1 Fuel 1 #5 injection Ti C2-175 Fig. 21 The amount of fuel injected by the injector valve is dependent upon the length of time it remains open. The optimum fuel injection timing is determined by transmitting a signal to the injector from the ECU according to varying engine operations. Feedback control is also accomplished by means of a learning control. As a result, the fuel injection control system is highly responsive and accurate in design and structure. The sequential fuel injection system is designed so that fuel is injected at a specific time to provide maximum air intake efficiency for each cylinder. n other words, fuel injection is completed just before the intake valve begins to open. 14

15 FUEL NJECTON SYSTEM [M603] 2-7 1) Fuel injection characteristics Fuel injection timing is basically expressed as indicated below : (1) During engine starts : Duration of fuel injection = Duration of fuel injection during engine starts (2) During normal operation : Basic duration of fuel injection x correction factor + voltage correction time Basic duration of fuel injection..... The basic length of time fuel is injected. This is determined by two factors--the amount of intake air detected by the air flow sensor and the engine speed (rpm) monitored by the crank angle sensor. Duration of fuel injection during engine starts..... Determined according to the engine coolant temperature detected by a signal emitted from the water temperature sensor to improve starting ability. Voltage correction time..... Compensates for the fuel injector's time lag affected by the battery voltage. 2) Correction coefficients Correction coefficients are used to correct the basic duration of fuel injection so that the air-fuel ratio meets the requirements of varying engine operations. These correction coefficients are classified as follows : (1) Air-fuel ratio coefficient : Allotted to provide the optimum air-fuel ratio in relation to engine speed and the basic amount of fuel injected. rig. t (3) Water temperature increment coefficient : Used to increase the amount of fuel injected in relation to a signal emitted from the water temperature sensor for easier starting of a cold engine. The lower the water temperature, the greater the increment rate. A d E d Fig. 24 Water temperature increment C (-4) (32) (68) (104) (140) (176) ( F) Water temperature Water temperature increment characteristic B2-300 (4) After-start increment coefficient : ncreases the amount of fuel injected for a certain period of time immediately after the engine starts to stabilize engine operation. E t 0 c At 1-1g. 22 t + At (2) Start increment coefficient : ncreases the amount of fuel injected only when cranking the engine, which improves starting ability. Fig t Elapse of time (after turning ignition switch OFF) After-start increment characteristic B

16 2-7 M6o31 FUEL NJECTON SYSTEM (5) Full increment coefficient : ncreases the amount of fuel injected by a signal emitted from the throttle sensor in relation to a signal emitted from the air flow sensor. (6) Acceleration increment coefficient : Compensates for time lags of air flow measurement and/or fuel injection during acceleration to provide quick response. m U c.: d E U C t-nt c t c t + of c Fig. 26 Amount of intake air (Throttle valve position) Full increment characteristic B2-302 Fig. 27 Variation in throttle valve position Acceleration increment characteristic B ) Air-fuel ratio feedback coefficient "alpha" This feedback coefficient utilizes the OZ sensor's electromotive force (voltage) as a signal to be entered into the ECU. When low voltage is entered, the ECU judges it as a lean mixture, and when high voltage is entered, it is judged as a rich mixture. n other words, when the air-fuel ratio is richer than the theoretical air-fuel ratio, the amount of fuel injected is decreased. When it is leaner, the amount of fuel injected is increased. n this way, the air-fuel ratio is compensated so that it comes as close to the theoretical air-fuel ratio as possible on which the three-way catalyst acts most effectively. (CO, HC and NOx are also reduced when the air-fuel ratio is close to theoretical air-fuel ratio.) ECU Combustion Exhaust gas Fuel increment signal Fuel injector chamber Low oxygen density 1 4 Fuel injection High oxygen Fuel decrement signal Fuel injection increases density 1 Fuel injection decreases. T 1 1 O sensor Lean air-fuel, Lean signal ratio 1 Detec- Rich air-fuel Rich signal tion ratio Fig. 28 B

17 FUEL NJECTON SYSTEM [M603) 2-7 4) Learning control system n a conventional air-fuel feedback control system, the basic amount of fuel injected (according to engine speed and various loads) is stored in the memory. After the ECU receives a signal emitted from the OZ sensor, the basic amount of fuel injected is corrected so that it is close to the theoretical air-fuel ratio. This means that the greater the air-fuel ratio is corrected, the lesser the control accuracy. n Subaru engines, however, an air-fuel ratio learning control system constantly memorizes the amount of correction required in relation to the basic amount of fuel to be injected (the basic amount of fuel injected is determined after several cycles of fuel injection), so that the correction affected by feedback control is minimized. Thus, quick response and accurate control of variations in air-fuel ratio, sensors' and actuators' characteristics during operation, as well as in the air-fuel ratio with the time of engine operation, are achieved. n addition, accurate control contributes much to stability of exhaust gases and driving performance. Cam angle sensor Crank angle sensor 1 Crank angle sensor 2 Air flow sensor Water temperature sensor i --W- ECU i 1 1 njector nhibitor switch 17

18 LftiJ~ 2-7 [M604] FUEL NJECTON SYSTEM 4. GNTON SYSTEM CONTROL This results in a reduced energy loss because no high This ignition system is a direct ignition system which is tension cords are needed. composed of an ECU, six ignition coils, two knock One knock sensor is installed on the left cylinder block, sensors and other sensors. Six ignition coils are directly and another on the right cylinder block, thus ensuring mounted to the spark plugs of the respective cylinders. accurate digital engine knock control. G switch Output signal f nput signal Electric current _ ECU r Crank angle Cam angle -J i sensor 1 j sensor ~~ u_ -~ #2 L LF-~' ~i; ~~_ ~ 1' Knock sensor 2 }-y -,Egl:--- Water temperatu re sensor gnitor Knock sensor 1 i Crank angle sensor 2! C gnition coil \\\\ 1 #1 #30 Air flow sensor C2-052 Fig

19 FUEL NJECTON SYSTEM [M604] 2-7 ECU determines the ignition timing based on the signal compression top dead center based on the signal from from crank angle sensor 1, and sends the signal for crank angle sensor 2 and cam angle sensor, igniter so as to spark the cylinder which is judged at BTDC i #t #6 700 i 10' -'130 ~-- i i j #3 #2 #5 lin~'n'aa~~amaawnnn #4 Zone 1, Zone 2 ' Zone 3 Zone 4 ~ ~ Fig. 30 When engine speed is low, the ECU sends out the ignition signal in synchronization with the 10 deg signal. C2-176 Zone. 1 : Judge engine speed with angular velocity. Zone. 2: Dowel-set with 70 signal. Zone. 3: gnition timing determined by ECU. Zone. 4: Actual ignition timing. 19

20 2-7 MS051 FUEL NJECTON SYSTEM 5. BY-PASS AR CONTROL (DLE SPEED CON- TROL) The ECU controls the operation of by-pass air control solenoid valve and auxiliary air control valve based on the signal from crank angle sensor 1, throttle sensor, vehicle speed sensor 2, water temperature sensor, ignition switch, A/C switch and inhibitor switch, etc. When coolant temperature is cold, the amount of bypass air is controlled by auxiliary air control valve and by-pass air control solenoid valve. When coolant temperature is hot, it is controlled by only by-pass air control solenoid valve. gnition switch Throttle body Crank angle sensor 1 Crank angle sensor 2 Cam angle sensor Throttle sensor Water temperature sensor Vehicle speed sensor 2 ECU By-pass air control solenoid valve Auxiliary air control valve A/C switch nhibitor switch Fig. 31 C

21 FUEL NJECTON SYSTEM [M607] EGR CONTROL The EGR system is composed of an EGR valve, EGR solenoid valve, EGR vacuum controller, ECU, etc. The exhaust gas is recirculated when the EGR solenoid valve opens to allow the intake manifold pressure to be transmitted to the EGR valve. ECU controls the EGR solenoid valve based on the signals sent from the water temperature sensor, OZ sensors 1 and 2, crank angle sensor 1, etc. Refer to C.2-1 Section 8. ntake manifold pressure line Exhaust gas line C2-053 Fig CANSTER PURGE CONTROL Canister purge takes place during operation of the ECU receives signals emitted from water temperature vehicle except under certain conditions (during idle, sensor, vehicle speed sensor 2 and crank angle sensor etc.). 1 to control purge control solenoid valve. Refer to C.2-1 Section 9. 21

22 2-7 [M608] FUEL NJECTON SYSTEM 8. RADATOR FAN CONTROL The radiator fan operation has four steps : off (OFF), low (Lo), medium (MD), and high (H) to reduce noise and load. The operating condition of the radiator fan is determined by the combination of signals sent from the A/C switch, A/C trinary switch, vehicle speed sensor 2 and water temperature sensor. A/C switch Vehicle speed Water temperature A/C trinary switch Operation ECU output signal of ' O O radiator fan X X X 10(6) 20112) 89(192) Fan relay NO. 95(203) Main fan Sub fan Unit : km/h (mph) Unit : C ( F) Unit : kg/cm2 No. 1 No. 2 (RH) (LH) X - LO LO X 0 - MD MD X 0 X 0 - MD MD 0 0 H H X - LO LO X X H H 0 X H H 0 H H X - - OFF OFF X 0 - LO LO 0 X - - OFF OFF MD MD 0 : Signal ON X : signal OFF 9. ENGNE TORQUE CONTROL n order to reduce gear shift shocks and protect transmission gears, engine torque is controlled shifting up under heavy loads or when the transmission is in the manual mode. 10. A/C SYSTEM CONTROL The ECU controls ON/OFF of the air conditioning (A/C) system. n addition, it controls the amount of electric current sent to the NC compressor, thereby controlling the quantity of refrigerant sent out by the compressor. When the A/C switch is set to ON when the coolant temperature is high, the refrigerant delivery quantity is reduced to lower the coolant temperature, thereby protecting the engine itself. The same control system is adopted to smooth engine speed variations when the A/C switch is turned ON or OFF. 22

23 FUEL NJECTON SYSTEM [M Self-diagnosis System 1. GENERAL The self-diagnosis system detects and indicates a fault in various inputs and outputs of the complex electronic control. The warning light (CHECK ENGNE light) on the instrument panel indicates occurrence of a fault or trouble. Further, against such a failure or sensors as may disable the drive, the fail-safe function is provided to ensure the minimal driveability. 2. FUNCTON OF SELF-DAGNOSS The self-diagnosis function has four modes : U-check mode, Read memory mode, D-check mode and Clear memory mode. Two terminals (Read memory and Test mode) and light (CHECK ENGNE light) are used. The DAG. terminals are for mode selection and the light monitors the type of problem. Relationship between modes and connectors l ~1 ~ DAG. terminal / Diagnosis connector (Black) ~ Select monitor _ c, 1 \ connector (Yellow) 1 Test mode of MPF 2 Read memory of MPF 3 Clear memory of SRS 4-5 Test mode of power steering 6 Read memory of power steering 7 Diagnosis of power steering 8 Diagnosis of passive belt 9 Diagnosis of SRS 10 Ground Mode Engine Read memory Test mode terminal terminal U-check gnition ON DSCONNECT DSCONNECT Read memory gnition ON CONNECT DSCONNECT D-check Clear memory gnition ON (engine on) gnition ON (engine on) DSCONNECT CONNECT CONNECT CONNECT U-check mode The U-check is a user-oriented mode in which only the MPF components necessary for start-up and drive are diagnosed. On occurrence of a fault, the warning light (CHECK ENGNE light) is lighted to indicate to the user that the dealer's inspection is necessary. The diagnosis of other parts which do not give significant adverse effect to start-up and drive are excluded from this mode in order to avoid unnecessary uneasiness to be taken by the user. Read memory mode This mode is used by the dealer to read past problems (even when the vehicle's monitor light are off). t is most effective in detecting poor contact or loose connections of connectors, harnesses, etc. D-check mode This mode is used bythe dealerto checkthe entire MPF system and detect faulty parts. Clear memory mode This mode is used by the dealer to clear the trouble code from the memory after the affected part is repaired. After checking on each mode, reinstall DAG. terminal to wire harness with tape. Fig. 33 C

24 2-7 nn7031 FUEL NJECTON SYSTEM 3. BASC OPERATON OF SELF-DAGNOSS SYSTEM No TROUBLE ' Mode Read memory terminal Test mode terminal Condition CHECK ENGNE light gnition switch ON U-check X X (Engine OFF) Engine ON gnition switch ON Read memory 0 X (Engine OFF) Blink Engine ON D-check Clear memory X gnition switch ON (Engine OFF) Engine ON gnition switch ON (Engine OFF) Engine ON ON OFF ON Vehicle specificaion code -> Blink * ON Vehicle specification code - Blink TROUBLE Mode Read memory terminal Test mode terminal Condition CHECK ENGNE light U-check X X gnition switch ON ON Read memory 0 X gnition switch ON (Engine OFF) Engine ON Trouble code (memory) ON D-check X 0 Engine ON Trouble code** Clear memory 0 0 Engine ON Trouble code** * When the engine operates at a speed greater than reached, the check engine light blinks. 2,000 rpm for more than 40 seconds, the check ** When the engine operates at a speed greater than engine light blinks. However, when all check items 2,000 rpm for more than 40 seconds, a trouble code check out "O.K.',' even before the 40 seconds is is emitted. 4. FAL-SAFE FUNCTON For the part which has been judged faulty in the selfdiagnosis, the ECU generates the associated pseudo signal (only when convertible to electric signal) and carries out the computational processing. n this fashion, the fail-safe function is performed. 24

25 5. TROUBLE CODES AND FAL-SAFE OPERATON FUEL NJECTON SYSTEM [S705] 2-7 Trouble code 11 Crank angle sensor 1 tem Contents of diagnosis Fail- safe operation No signal entered from crank angle sensor 1 more - than 3 seconds on start switch ON. 12 Starter switch Abnormal signal emitted from ignition switch. Turns starter switch signal OFF. 13 Cam angle sensor 14 njector #1 15 njector #2 No signal entered from cam angle sensor, but signal entered from crank angle sensor njector #3 Fuel injector inoperative. 17 njector #4 (Abnormal signal emitted from monitor circuit.) 18 njector #5 19 njector #6 21 Adjusts water to a specific temperature. Maintains radiator fan "ON" to prevent overheat- ing. Water temperature sen- Abnormal signal emitted from water temperature sor sensor. 22 Knock sensor 1 (RH) 23 Air flow sensor 24 _ Abnormal voltage produced in knock sensor mon- Sets regular fuel map and retards ignition timing itor circuit. by 5. Abnormal voltage input entered from air flow sen- Controls the amount of fuel (injected) in relation to sor. engine speed and throttle sensor or position. Prevents abnormal engine speed using "fuel cut" in relation engine speed, vehicle speed and throt- tle sensor position. Bypass air control sole- By-pass air control solenoid valve inoperated. noid valve (Abnormal signal produced in monitor circuit.) 28 Knock sensor 2 (LH) 29 Crank angle sensor 2 31 Throttle sensor Abnormal voltage produced in knock sensor mon- Sets regular fuel map and retards ignition timing itor circuit. by 5. No signal entered from crank angle sensor 1, but - two signals entered from cam angle sensor. Abnormal voltage input entered from throttle sen- Sets throttle sensor's voltage output to fixed sor. value. 32 OZ sensor 1 (RH) Oz sensor 1 inoperative Vehicle speed sensor 2 Abnormal voltage input entered from vehicle speed sensor 2. Sets vehicle speed signal to a fixed value. 34 EGR solenoid valve EGR solenoid valve inoperative Purge control solenoid valve Purge control solenoid valve inoperative OZ sensor 2 (LH) OZ sensor 2 inoperative Engine torque control Wiring harness between ECU and TCU is in short - circuit. 41 A/F learning control Faulty learning control function Atmospheric pressure sensor Faulty atmospheric pressure sensor build in ECU Neutral switch Abnormal signal entered from inhibitor switch Parking switch Abnormal signal entered from parking switch EGR gas temperature Abnormal signal emitted from EGR gas tempera- - sensor (CAL.) ture sensor. 56 EGR system (CAL.) EGR valve open/close stick, EGR hose disconnect - or exhaust pressure control valve damaged. 25

26 2-7 C0001 FUEL NJECTON SYSTEM C COMPONENT PARTS 1. ntake Manifold and Collector O 0 OO o n ( 1 EGR vacuum controller 2 EGR pipe cover 3 EGR valve 4 Gasket 5 Recirulation gas temperature sensor 6 Collector 7 Gasket A (RH) 8 ntake manifold R H 9 Gasket A (LH) 10 Fuel injector 11 O-ring A 12 O-ring B 13 Fuel pipe 14 Washer 15 nduction control valve ASSY 16 O-ring 17 ntake manifold LH 18 Gasket B (RH) 19 Gasket B (LH) Fig. 34 C

27 2. Air ntake Boot and Throttle Body FUEL NJECTON SYSTEM [C iu cm~ssion nose nn 11 Auxiliary air control valve Fig. 35 C

28 2-7 [C300] FUEL NJECTON SYSTEM 3. Air Cleaner `\ 1 Air flow sensor 2 Air cleaner upper cover 3 Air cleaner element 4 Air cleaner under cover 5 Clip 6 Bracket 7 Resonator CP Fig. 36 C

29 T TROUBLESHOOTNG 1. Supplemental Restraint System "Airbag" Airbag system wiring harness is routed near the MPF control unit (ECU), main relay and fuel pump relay. a. All Airbag system wiring harness and connectors are colored yellow. Do not use electrical test equipment on these circuit. b. Be careful not to damage Airbag system wiring harness when servicing the MPF control unit (ECU), main relay and fuel pump relay. 2. Precautions 1) Never connect the battery in reverse polarity. The MPF control unit will be destroyed instantly. The fuel injector and other part will be damaged in just a few minutes more. 2) Do not disconnect the battery terminals while the engine is running. e A large counter electromotive force will be generated in the alternator, and this voltage may damage electronic parts such as ECU (MPF control unit), etc. 3) Before disconnecting the connectors of each sensor and the ECU, be sure the turn off the ignition switch. Otherwise, the ECU may be damaged. 4) The connectors to each sensor in the engine compartment and the harness connectors on the engine side and body side are all designed to be waterproof. However, it is still necessary to take care not to allow water to get into the connectors when washing the vehicle, or when servicing the vehicle on a rainy day. 5) Every MPF-related part is a precision part. Do not drop them. 6) Observe the following cautions when installing a radio in MPF equipped models. a. The antenna must be kept as far apart as possible from the control unit. (The ECU is located under the steering column, inside of the instrument panel lower trim panel.) b. The antenna feeder must be placed as far apart as possible from the ECU and MPF harness. c. Carefully adjust the antenna for correct matching. d. When mounting a large power type radio, pay special attention to items a. thru c. above. ncorrect installation of the radio may affect the operation of the ECU. 7) Before disconnecting the fuel hose, disconnect the fuel pump connector and crank the engine for more than five seconds to release pressure in the fuel system. f engine starts during this operation, run it until it stops. FUEL NJECTON SYSTEM [T305] Pre-inspection Before troubleshooting, check the following items which might affect engine problems : 1. Power supply 1) Measure battery voltage and specific gravity of electrolyte. Standard voltage : 12 V Specific gravity : Above ) Check the condition of the main and other fuses, and harnesses and connectors. Also check for proper grounding. 2. Caps and plugs 1) Check that the fuel cap is properly closed. 2) Check that the oil filler cap is properly closed. 3) Check that the oil level gauge is properly inserted. 3. ntake manifold vacuum pressure 1) After warming up the engine, measure intake manifold vacuum pressure while at idle. Standard vacuum pressure : Approx kpa (- 500 mmhg, in Hg). Refer to C.2-2 [W5A0]. 2) Unusual vacuum pressure occurs because of air leaks, fuel or engine problems. n such a case, engine idles roughly. 4. Fuel pressure 1) Release fuel pressure Refer to C.2-8 [W1A0]. 2) Connect fuel pressure gauge between fuel filter and hose, and measure fuel pressure at idling. Refer to C.2-8 [W2A0]. Fuel pressure : kpa ( kg/cm', psi) 5. Engine grounding Make sure the engine grounding terminal is properly connected to the engine. 29

30 2-7 T400) FUEL NJECTON SYSTEM 4. Electric Unit Location 1. SENSOR AND SOLENOD VALVE solenoid valve solenoid valve Fig. 37 C

31 FUEL NJECTON SYSTEM [T401] 2-7 > O, sensor 1 i /. s- ~r= ~ \ Engine ground ; l - < < - Power steering switch- O2 sensor 2 \ \ OO / Cam angle sensor t (_ i \ ~ 1 `1 ~- ~~\ _. (- ` - ~ s1 \ /1~~ _ Crank angle sensor 2 - Crank angle -` sensor 1 OJ\/ ~ Knock sensor 1 "'-~h ~ 1~\\\ Air flow sensor i,d~-{// -~ r 71 Knock sensor 2 1 C

32 2-7 [T4021 FUEL NJECTON SYSTEM 2. CONTROL UNT AND RELAY ~`1i, ~ 1r~\c \ Fuel pump relay Main relay ~-- rj w \. + DAG. terminal Y l i, Select 4 monitor '': connector! ia D agnosis connector L Fig. 38 Supplemental Restraint System "Airbag" Airbag system wiring harness is routed near the MPF control unit (ECU), main relay and fuel pump relay. 32 C2-397 a. All Airbag system wiring harness and connectors are colored yellow. Do not use electrical test equipment on these circuit. b. Be careful not to damage Airbag system wiring harness when servicing the MPF control unit (ECU), main relay and fuel pump relay.

33 FUEL NJECTON SYSTEM [T5AO Troubleshooting Chart for Self-diagnosis System A : BASC TROUBLESHOOTNG PROCEDURE Trouble occurs READ MEMORY MODE Engine does not start Engine start 5. Troubleshooting for -Engine Starting Failure" D-CHECK MODE [T6AO.*- No trouble code Troubleshooting in accordance with trouble code. * nspection using Troubleshooting Chart with Se- lect Monitor [T8A0] or inspection using General Troubleshooting Table [T9A0] Repair Trouble code designated D-CHECK MODE No trouble code designated CLEAR MEMORY MODE *: When more than one trouble code is outputted, begin troubleshooting with the smallest trouble code number and proceed to the next higher code. After correcting each problem, conduct the D-check and ensure that the corresponding trouble code no longer appears. ** : When a trouble code is displayed in the read-memory mode, conduct troubleshooting measures which correspond with the code. - a. Check the connector while it is connected unless specified otherwise. b. Be sure to check again from the beginning in order to prevent secondary trouble caused by repair work. c. When checking with the vacuum hose disconnected from the vacuum switch at E/G on, be sure to plug the hose. 33

34 2-7 [T5B1] FUEL NJECTON SYSTEM B : LST OF TROUBLE CODES 1. TROUBLE CODES Trouble code tem Diagnosis 11 Crank angle sensor 1 No signal from crank angle sensor 1 for more than 3 seconds after start switch ON. 12 Starter switch Abnormal signal from ignition switch. 13 Cam angle sensor No signal from cam angle sensor, but signal from crank angle sensor njector #1 15 njector #2 16 njector #3 Fuel injector inoperative. 17 njector #4 (Abnormal signal from monitor circuit.) 18 njector #5 19 njector #6 21 Water temperature sensor Abnormal signal from water temperature sensor. 22 Knock sensor 1 (RH) Abnormal voltage in knock sensor monitor circuit. 23 Air flow sensor Abnormal voltage from air flow sensor. 24 By-pass air control solenoid valve By-pass air control solenoid valve inoperated. (Abnormal signal in monitor circuit.) 28 Knock sensor 2 (LH) Abnormal voltage in knock sensor monitor circuit. 29 Crank angle sensor 2 No signal from crank angle sensor 2, but two signals from crank angle sensor Throttle sensor Abnormal voltage from throttle sensor. 32 OZ sensor 1 (RH) OZ sensor 1 inoperative. 33 Vehicle speed sensor No signal from vehicle speed sensor EGR solenoid valve EGR solenoid valve inoperative. 35 Purge control solenoid valve Purge control solenoid valve inoperative. 37 OZ sensor 2 (LH) OZ sensor 2 inoperative. 38 Engine torque control Wiring harness between ECU and TCU is in short circuit. 41 A/F learning control Faulty learning control function. 45 Atmospheric pressure sensor Faulty atmospheric pressure sensor inside ECU. 51 Neutral switch Abnormal signal from inhibitor switch. 52 Parking switch Abnormal signal from parking switch. 55 EGR gas temperature sensor (CAL.) Abnormal signal from EGR gas temperature sensor. 56 EGR system (CAL.) EGR valve open/close stick, EGR hose disconnect or exhaust pressure control valve damaged. 34

35 FUEL NJECTON SYSTEM [T5B2] HOW TO READ TROUBLE CODE (FLASHNG) The CHECK ENGNE light flashes the code corresponding to the faulty part. The long segment (1.2 sec on) indicates a --ten", and the short segment (0.2 sec on) signifies --one". Example : When only one part has failed 11 =N Flashing code 12 (unit: second) ~ =me When two or more parts have failed : Flashing MEMO ME M M codes 12 and 21 (unit : second) ~ t B2-311 Fig

36 2-7 [T5C0] FUEL NJECTON SYSTEM C : READ MEMORY MODE Vehicle returned to dealer Turn ignition switch OFF. Connect read memory terminal. Turn ignition switch ON (engine OFF). Trouble code is indicated. Check ifcheck ENGNE light lights up. YES NO ~ nspect control unit power supply --~ and ground line, and CHECK ENGNE nlight line. CHECK ENGNE light blinks. Confirm trouble code. Disconnect read memory terminal. Disconnect read memory terminal. Self-diagnosis systems are O.K. Trouble is in a system other than a self-diagnosis system. Conduct D-check. 36

37 FUEL NJECTON SYSTEM [T5D0] 2-7 D : D-CHECK MODE Start engine. Warm up engine. Turn ignition switch OFF. Connect test mode terminal. Turn ignition switch ON (engine off). Check if CHECK ENGNE light turns on. YES NO nspect control unit power supply and ground line, and --' CHECK ENGNE light line. Start engine. Check if CHECK ENGNE light indicates vehicle specification code. NO YES Check if specification code coincides with vehicle specifi- ~ NO ~ nspect vehicle identification line. cations. Repair harness or connector. YES Drive at speed greater than 11 one minute. km/h (7 mph) for at least Warm up engine above 2,000 rpm. NO Check if CHECK ENGNE light blinks. NO Check if CHECK ENGNE light indicates trouble code. YES YES Turn ignition switch OFF. Disconnect test mode terminal. Confirm trouble code. Self-diagnosis systems are O.K. Trouble is in a system other than a self-diagnosis system. Make sequential checks of trouble codes. 37

38 2-7 [T5EO FUEL NJECTON SYSTEM E : CLEAR MEMORY MODE Start engine. Warm up engine. Turn ignition switch OFF. Connect test mode terminal. Connect read memory terminal. Turn ignition switch ON (engine off). CHECK ENGNE light turns ON. ~ Depress accelerator pedal completely and then return it to half-throttle position and hold it there for two seconds. Release accelerator pedal completely. Start engine. CHECK ENGNE light blinks to indicate vehicle specification code. O YES Drive at speed greater than 11 one minutes. km/h (7 mph) for at least Warm up engine above 2,000 rpm. Check if CHECK ENGNE light blinks. YES NO Check if CHECK ENGNE light indicates trouble code. YES Turn ignition switch OFF. Confirm trouble code. Disconnect test mode terminal and read memory terminal. Make sequential checks of trouble codes. END After sequential checks, go to D-check mode again. 38

39 6. Output Modes of Select Monitor 1. FUNCTON MODE MODE Contents FUEL NJECTON SYSTEM [T601] 2-7 Abbreviation Unit of measure F00 ROM-D number YEAR - Model year of vehicle Contents of display F01 Battery voltage VB V Battery voltage supplied to ECU. F02 Vehicle speed signal VSP m/h F03 Vehicle speed signal VSP km/h Vehi cle speed from ve hi cl e spee d sensor 2. F04 Engine speed signal EREV rpm Engine speed from crank angle sensor 1. F05 Water temperature signal TW degf F06 Water temperature signal TW degc Coolant temperature from water temperature sensor. F07 gnition timing ADVS deg gnition timing calculated by ECU. F08 Air flow signal QA V ntake air flow converted to volts F09 Load data LDATA - Engine load. F10 Throttle position signal THV V Throttle position converted to volts F11 njector pulse width TM ms gnition timing calculated by ECU. F12 By-pass air control SC % "Duty" ratio on by-pass air control system. F13 OZ sensor 1 (RH) signal 02R V Voltage from OZ sensor 1 (RH) F14 02 sensor 2 (LH) signal 02L V Voltage from OZ sensor 2 (LH). F15 Oz Max. (RH) 02Rmax V Maximum voltage from OZ sensor 1 (RH). F16 02 Min. (RH) 02Rmin V Minimum voltage from OZ sensor 1 (RH). F17 02 Max. (LH) 02Lmax V Maximum voltage from OZ sensor 2 (LH). F18 Oz Min. (LH) 021-min V Minimum voltage. from OZ sensor 2 (LH). F19 A/F correction coefficient 1 ALPHA1 % A/F ratio correction determined by ECU from OZ sensor F20 A/F correction coefficient 2 ALPHA2 % 1 and/or OZ sensor 2 signal(s). F21 Knock sensor signal RTRD deg Correction determined by ECU from knock sensor 1 and/or 2 signal(s). F22 Canister purge control CPCD % "Duty" ratio on purge control system. F23 Atmospheric pressure BARO.P mmhg - FAO ON» OFF signal FA1 ON N OFF signal FA2 ON» OFF signal FA3 ON "-" OFF signal FA4. ON "~ OFF signal FA5 ON <-" OFF signal FBO Trouble code DAG - Trouble code in U- or D-check mode. FB1 Trouble code DAG - Trouble code in read memory mode. FCO Clear memory - - Used to clear memory. 39