Engine Controls - System/component Tests Toyota Celica T180

INTRODUCTION

Before testing separate components or systems, perform procedures in BASIC TESTING article in this section. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in TESTS W/CODES article in this section.

Note. Testing individual components does not isolate shorts or opens. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

Initial Checks

1. Check air intake system for cracks or restrictions. Inspect exhaust system for leaks or restrictions. Check for leaks or clogging between cylinder head and turbocharger inlet.
2. Check air intake system and exhaust system for signs of oil leaks from turbocharger. Excessive carbon deposits on the turbine wheel may indicate leaking oil seals in the turbocharger. Replace turbocharger if oil seals are leaking.

Actuator & Wastegate

Disconnect all air intake hoses from turbocharger and set aside. Disconnect actuator hose. Using a pressure gauge and pump, apply 9.4 psi (.66 kg/cm 2 ) of pressure to actuator hose. (Scheme 94) Ensure rod moves.0098" (.25 mm) or more. If rod does not move as indicate, replace turbocharger assembly.

Scheme 94

Impeller Wheel Rotation

Disconnect air cleaner hose. Turn impeller wheel to verify smooth rotation. If impeller wheel does not turn or drags, replace turbocharger assembly.

Turbine Shaft End Play & Radial Play

Disconnect intake and exhaust hoses from turbocharger. Use a dial indicator to measure turbine shaft end play and radial play. End play is measured through the oil outlet hole. Replace turbocharger if specifications are out of range. See TURBINE SHAFT END & RADIAL PLAY table.

TURBINE SHAFT END & RADIAL PLAY

Scheme 95

1. Ensure all intake air hoses are connected. Place pressure hose and "T" fitting in actuator hose leading to intake manifold. (Scheme 95) Start engine.
2. Drive vehicle with engine running at 2800 RPM or more with throttle fully open and transaxle in second gear. Check pressure. See «TURBOCHARGER PRESSURE»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
3. If pressure is less than specification, check intake air and exhaust systems for leaks. If there are no leaks, replace turbocharger. If pressure is greater than specification, check actuator hose for leaks or cracks. If no leaks or cracks are present, replace turbocharger.

Note. To check turbocharger pressure sensor and vacuum switching valve, see ENGINE SENSORS & SWITCHES in this article.

TURBOCHARGER PRESSURE

Celica (2.0L)

1. Using a vacuum "T", connect a vacuum gauge into vacuum line between vacuum switching valve and Toyota Variable Induction System (T-VIS) diaphragm. (Scheme 96) Connect tachometer to engine. See ADJUSTMENTS article in this section for correct tachometer attachment.
2. Start engine and warm to normal operating temperature. Vacuum gauge should show high vacuum at idle (internal throttle valve closed). Increase engine speed to greater than 4000 RPM.
3. Vacuum gauge should indicate zero. If gauge does not indicate zero, use hand held vacuum pump to verify T-VIS diaphragm holds vacuum. If T-VIS diaphragm holds vacuum, go to next step.
4. Check T-VIS vacuum switching valve by removing top of intake manifold. Ensure resistance across vacuum switching valve connector terminals is 33-39 ohms. Ensure there is no continuity between wiring terminals and valve body. Check airflow through valve. (Scheme 97)

Scheme 96

Scheme 97

AIRFLOW METER (3S-GTE)

Turn ignition off. Unplug wiring connector from air- flow meter. Note terminal identification. (Scheme 99) Use ohmmeter to measure resistance between specified terminals. On Supra Turbo models, use only an analog ohmmeter. See AIRFLOW METER RESISTANCE SPECIFICATIONS table. Replace airflow meter if not within specification.

Scheme 98

Scheme 99

AIRFLOW METER RESISTANCE SPECIFICATIONS (3S-GTE)

AIR TEMPERATURE SENSOR (CELICA NON-TURBO)

Ensure ignition is off. Unplug air temperature sensor. Measure resistance across air temperature sensor terminals at specified temperature. (Scheme 100) Replace air temperature sensor if not within specification.

Scheme 100

COLD START INJECTOR TIME SWITCH

Turn ignition off. Remove connector from switch. (Scheme 101)-10 for Time Switch Location. Measure resistance across switch terminals at specified temperature. (Scheme 104) Replace switch if resistance is not within specification. See COLD START INJECTOR TIME SWITCH RESISTANCE SPECIFICATIONS table.

COLD START INJECTOR TIME SWITCH RESISTANCE SPECIFICATIONS

Scheme 101

Scheme 102

Scheme 103

Scheme 104

COOLANT TEMPERATURE SENSOR

1. Ensure ignition is off. Unplug connector from sensor. For sensor location (Scheme 102)and (Scheme 103).
2. Using ohmmeter, check resistance between sensor terminals. Replace sensor if resistance is not within specification at specified temperature. (Scheme 105)

Scheme 105

EGR GAS TEMPERATURE SENSOR

1. Remove sensor from side of EGR valve. Place threaded end of sensor and thermometer in container of oil. (Scheme 106)
2. Attach ohmmeter to sensor terminals. Heat oil and note resistance at specified temperature. See «EGR TEMPERATURE SENSOR SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Replace sensor if not within specification.

EGR TEMPERATURE SENSOR SPECIFICATIONS

Scheme 106

KNOCK SENSOR (3S-GTE)

Probable causes of knock sensor problems include the following

1. Open or short in knock sensor circuit.
2. Knock sensor (looseness etc.).
3. Knock control in ECU is faulty.

Knock sensor problems can also set fault codes 52 and 53. For code charts, see TESTS W/CODES article in this section.

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

See VACUUM SENSOR under ENGINE SENSORS & SWITCHES in this article.

NEUTRAL/START SWITCH

Unplug switch connector at transmission or transaxle. Note terminal identification. (Scheme 107)and (Scheme 108). Using ohmmeter, check for continuity at specified terminals with gearshift in correct range. See NEUTRAL/START SWITCH SPECIFICATIONS table.

NEUTRAL/START SWITCH SPECIFICATIONS

Scheme 107

Scheme 108

OXYGEN (O2) SENSOR FEEDBACK VOLTAGE TEST

1. Warm engine to normal operating temperature. Connect analog-type voltmeter to engine check connector VF1 (or VF) and E1 terminals. (Scheme 109) Perform procedures listed in (Scheme 110).
2. Depending on model application, some vehicles may be equipped with a main O2 sensor, sub-oxygen sensor and an O2 sensor heater. See «OXYGEN SENSOR USAGE»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.

Note. Codes No. 21, 25, 26 and 27 are O2 sensor circuit codes. Also check for coolant temperature sensor Code No. 22. Faulty coolant temperature sensor could cause faulty O2 sensor readings.

OXYGEN SENSOR USAGE

Scheme 109

Scheme 110

SUB-OXYGEN SENSOR (2.2L CALIF.)

1. Warm engine to normal operating temperature. Check ECU for stored fault code(s). If sub-oxygen sensor or circuit fails, a Code 27 fault code will set in ECU memory. Clear codes if present. See CLEARING TROUBLE CODES in TESTS W/CODES article in this section. NOTE: DO NOT drive vehicle more than 62 MPH or code will cancel.
2. Drive vehicle between 50 and 61 MPH for at least 5 minutes in 4th or 5th gear (M/T) or Drive (A/T).
3. Fully depress accelerator pedal for at least 10 seconds with engine RPM at least 3000 RPM. Stop engine and turn ignition off.
4. Repeat previous steps and note if Code 27 exists again. If Code 27 exists again, check sub-oxygen sensor circuit for continuity, shorts or grounds. Replace sub-oxygen sensor if circuit is okay.

OXYGEN (O2) SENSOR HEATER (1.6L FEDERAL & 2.0L)

1. Unplug O2 sensor connector. Using ohmmeter, measure resistance between sensor terminals. +B and HT. (Scheme 111) Replace sensor if resistance is not 5.1-6.3 ohms.
2. A Code No. 21 is also an indicator of a problem in O2 sensor circuit. Code No. 21 will set if O2 sensor heater circuit opens or shorts to ground on HT wire from sensor to ECU.

Scheme 111

PICK-UP COILS

See PICK-UP AIR GAP and PICK-UP COIL RESISTANCE in BASIC TESTING article in this section.

THROTTLE POSITION SENSOR (TPS)

Turn ignition off. Unplug electrical connector at TPS on throttle body. Note terminal identification. (Scheme 112)and (Scheme 113). Insert specified thickness feeler gauge between throttle stop screw and throttle lever. See TPS RESISTANCE SPECIFICATIONS table. Using an ohmmeter, check for resistance or continuity. Replace or adjust TPS if not within specification.

TPS RESISTANCE SPECIFICATIONS

Scheme 112

Scheme 113

TURBOCHARGING PRESSURE SENSOR

1. To check power source, turn ignition on. Unplug turbocharging pressure sensor. Measure voltage between terminals VC and E2 of harness connector. (Scheme 114) Voltage should be 4.5-5.5 volts.
2. To check power output, turn ignition on. Unplug turbocharging pressure sensor vacuum hose from intake manifold. Connect voltmeter to terminals PIM and E2 of ECU connector. See WIRING DIAGRAMS article in this section. Measure output voltage under ambient atmospheric pressure.
3. Attach a vacuum pump to turbocharging pressure sensor vacuum hose and apply vacuum in specified stages. (Scheme 115) Measure and record voltage readings for each stage of applied vacuum. See «VACUUM/VOLTAGE SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Replace sensor if readings are not within specifications.

Scheme 114

Scheme 115

VACUUM/VOLTAGE SPECIFICATIONS

TURBOCHARGER VACUUM SWITCHING VALVE (VSV)

1. Using ohmmeter, check continuity between turbocharger VSV connector terminals. (Scheme 116) Resistance should be 24-30 ohms. Ensure no continuity exists between VSV case (body) and each terminal. If continuity is not as specified, replace VSV.
2. Ensure air blown into pipe "E" does not flow from pipe "F". (Scheme 116) If air does not pass out pipe "F", apply battery voltage and ground to VSV terminals. Air should now flow from pipe "E" to pipe "F". If air does not flow as indicated, replace VSV.

Scheme 116

VACUUM SENSOR (NON-TURBO)

1. Ensure ignition switch is off. Locate sensor on center of firewall. Unplug vacuum sensor electrical connector. Turn ignition on, with engine off. NOTE: Vacuum sensor is also known as Manifold Absolute Pressure (MAP) sensor.
2. Measure voltage between both terminals of sensor harness. (Scheme 117) Voltage should be 4.0-6.0 volts (4.5-5.5 volts for Celica). This is reference voltage from ECU. If voltage is not present or low, check wiring and ECU.
3. Turn ignition off. Plug in vacuum sensor electrical connector. Disconnect vacuum sensor hose from intake chamber. Turn ignition on with engine off. With ECU connectors in place, connect DVOM to back side of terminals E2 and PIM. (Scheme 118)-27.
4. Connect hand-held vacuum pump/gauge to sensor vacuum hose. Measure voltage drop at specified vacuum reading. See «VACUUM SENSOR SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Replace sensor if defective.

VACUUM SENSOR SPECIFICATIONS

Scheme 117

Scheme 118

Scheme 119

Scheme 120

VEHICLE SPEED SENSOR

1. Apply positive battery voltage to terminal No. 1 of speed sensor. (Scheme 121) Connect terminal No. 3 to ground. Connect ohmmeter between terminal No. 2 and negative terminal of battery.
2. Ohmmeter should show continuity as meter shaft is rotated (4 times per revolution). If ohmmeter does not deflect as specified, replace speed sensor.

Scheme 121

CIRCUIT OPENING RELAY

Circuit opening relay is located under ECU, under center of dash. To check circuit opening relay (Scheme 122)and (Scheme 123). Replace relay if continuity is not as specified.

Note. During cranking, there should be 12 volts present at FP terminal of circuit opening relay. This is the fuel pump (or fuel pump relay) line. See WIRING DIAGRAMS article in this section for wire color.

Scheme 122

Scheme 123

EFI MAIN RELAY

EFI Main Relay is located in relay bank, on left front fenderwell. To test EFI main relay (Scheme 124) Replace relay if defective.

FUEL PUMP RELAY

See FUEL DELIVERY under FUEL SYSTEM for testing.

Scheme 124

FUEL SYSTEM

Fuel Pressure Release

Disconnect negative battery terminal. Place container under fitting to be loosened. Use a rag to cover fuel line/component. Slowly loosen fitting, allowing pressurized fuel to spill into container. After fuel system has depressurized, disconnect and plug fitting.

FUEL DELIVERY

For fuel pump pressure and fuel pressure regulator testing, see BASIC TESTING article in this section.

Fuel Pump Relay & Resistor (Turbo)

Fuel Pump Relay is located in relay box number 5, on left radiator support. For Resistor location (Scheme 102) To test relay and resistor (Scheme 125) Replace relay or resistor if defective.

Scheme 125

Fuel Injector Solenoid Resistor (Celica Turbo & Supra Turbo)

1. Turn ignition off. Unplug injector solenoid resistor. (Scheme 102)
2. Check resistance between terminal B+ and other terminals. (Scheme 126)
3. If resistance is not 4-6 ohms, replace solenoid resistor. If resistance is as specified, check power feed to fuel injector resistor.

Scheme 126

Fuel Injectors

1. Turn ignition off. Unplug each injector connector. Measure resistance across both terminals. If resistance is not 2-4 ohms (approx. 13.8 on Non-Turbo) measured at 68°F (20°C), replace fuel injector.
2. To check injector spray pattern and volume, relieve fuel system pressure. Remove injectors from engine. Disconnect fuel hose from fuel filter outlet. Use Fuel Pressure Gauge (09268-41045) to "T" fuel injector between fuel filter and fuel pressure regulator. (Scheme 127)and (Scheme 128).
3. Place injector into clean container. Place tube on end of injector to prevent fuel from spilling. Connect Fuel Injector Tester (09842-30070) or trigger box with appropriate resistor to fuel injector. Turn ignition on, with engine off.
4. Connect jumper wire to engine check connector terminals FP and +B to pressurize fuel system. For engine check connector locations (Scheme 109) Connector terminals are marked on inside of check connector cover.
5. Trigger injector for 15 seconds. Measure volume and check spray pattern. Test each injector 2-3 times. Replace injector if volume is not as specified. See «FUEL INJECTOR VOLUME SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
6. Disconnect injector trigger. Fuel leakage from end of injector should be one drop or less in one minute. Replace injector if leakage is more than specified.

FUEL INJECTOR VOLUME SPECIFICATIONS

Scheme 127

Scheme 128

Fuel Pressure-Up System

1. Ensure coolant temperature sensor, air temperature sensor (in airflow meter) and circuits are operating correctly. See «ENGINE SENSORS & SWITCHES»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests).
2. Fuel pressure-up system is controlled by ECU through a vacuum switching valve. The vacuum switching valve is fed current through the EFI main relay when the ignition is turned on. ECU controls the ground circuit. ECU will activate vacuum switching valve for 90-180 seconds when restarting engine at normal operating temperature.
3. Remove vacuum switching valve from lower side of intake manifold runners. Check for continuity across valve wiring terminals. Resistance should be about 33-50 ohms at room temperature. There should be no continuity between each terminal and body of valve. To check operation (Scheme 129)

Scheme 129

Deceleration Fuel-Cut System

1. Connect a tachometer to engine (to monitor needle fluctuations). See ADJUSTMENTS article in this section for tachometer attaching points. Start engine and warm to operating temperature. Ensure A/C and other accessories are off.
2. Unplug throttle position sensor connector from throttle position sensor. Short terminals IDL and E1 (or E2) on wire side of connector. (Scheme 130)and (Scheme 131).
3. Gradually raise engine RPM. Fuel-cut operation can be checked by noting the fluctuation of tachometer needle. Fluctuation indicates fuel-cut system is being turned on and off. (Scheme 132) Check that fuel-cut points and fuel return points are within specifications. See «DECELERATION FUEL-CUT & FUEL RETURN RPM»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.

DECELERATION FUEL-CUT & FUEL RETURN RPM

Scheme 130

Scheme 131

Scheme 132

Cold Start Injector

1. Disconnect negative battery cable. Disconnect cold start injector wiring harness connector. Check resistance between terminals of injector. Replace injector if resistance is not 2-4 ohms. If resistance is okay, relieve fuel system pressure.
2. Remove cold start injector from vehicle. Install fuel hose to injector. Install system Union Adapters (9268-41045) to delivery pipe and cold start injector. Connect fuel hose to union adapters. (Scheme 133) Connect Jumper Harness (9842-30050) to cold start injector.
3. Place container under cold start injector. Connect jumper wire to engine check connector terminals FP and B+ to pressurize fuel system. For engine check connector locations (Scheme 109) Turn ignition on, with engine off. CAUTION: Perform cold start injector connector test in shortest possible time.
4. Connect probes of Fuel Injection Tester (09842-30070) to battery. Connect other end of tester to cold start injector. (Scheme 133) Ensure fuel spray is an even cone shape.
5. Disconnect fuel injector tester harness and observe cold start injector. Maximum leakage should be one drop per minute with fuel pressure applied. Clean or replace cold start injector if defective.

Scheme 133

Note. Cold start injector is controlled by cold start injector time switch when ignition switch is turned on.

For test procedures, see ENGINE SENSORS & SWITCHES .

AUXILIARY AIR VALVE SYSTEM (1.6L)

1. With engine coolant less than 176°F (80°C), install tachometer. See ADJUSTMENTS article in this section for tachometer attaching points.
2. Remove air cleaner. Start engine. Place finger over air valve port to block airflow. (Scheme 134) Engine speed should drop noticeably.
3. Warm engine to normal operating temperature. Place finger over air valve port to block airflow. Engine speed should not drop more than 50 RPM (100 RPM for Celica).
4. If engine RPM does not respond as indicated, check for vacuum leaks after the valve or restricted chamber in auxiliary air valve circuit. If no defects are found, replace auxiliary air valve.

Scheme 134

Scheme 135

1. Warm engine to normal operating temperature. Ensure idle speed is correct. Apply parking brake, block drive wheels and place transaxle in Neutral.
2. Install jumper wire between terminals TE1 (or T) and E1 of check connector located near left shock tower. (Scheme 135) Engine RPM should increase to 1000-1300 RPM for 5 seconds and then return to idle.
3. If engine RPM was not within specification, check ISC valve, wiring to ECU, and ECU grounds. If engine RPM was within specification, remove jumper wire. Turn ignition off.
4. Unplug ISC valve connector on bottom of throttle body. Using ohmmeter, measure resistance between terminals B+ and ISC1, and between ISC2 and B+. (Scheme 136) Replace valve if resistance is not within 19.3-22.3 ohms.

Scheme 136

2.0L

1. Warm engine to normal operating temperature. Ensure idle speed is correct. Apply parking brake, block drive wheels and place transaxle in Neutral.
2. Unplug ISC valve connector on bottom of throttle body. Engine RPM should increase 1000 RPM or more. Plug in ISC valve connector. Engine should return to idle speed (750-850 RPM). If engine RPM does not respond as specified, check ISC valve, wiring to ECU, and ECU grounds.
3. To check ISC valve, turn ignition off. Unplug ISC valve connector on bottom of throttle body. Using ohmmeter, measure resistance between center terminal and each outer terminal individually. (Scheme 135) Replace valve if resistance is not 19.3-22.3 ohms.

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC TESTING article in this section.

Probable causes of knock sensor problems include the following

1. Open or short in knock sensor circuit.
2. Knock sensor (looseness etc.).
3. Knock control in ECU is faulty.

Knock sensor problems can also set fault codes 52 and 53. For code charts, see TESTS W/CODES article in this section.

System Test

1. Ensure modulator filter is clean and in good condition prior to performing test. Clean filter with compressed air. Disconnect vacuum hose from EGR valve.
2. Using a "T" connector, connect a vacuum gauge in EGR valve vacuum line. Ensure engine starts and runs smoothly at idle. This ensures proper seating of EGR valve.
3. Different vacuum switching valves are used depending on model. (Scheme 138)-46, and 47-49. The Bimetallic Vacuum Switching Valve (BVSV), Vacuum Switching Valve (VSV) and EGR modulator can be checked with engine coolant temperature less than minimum temperature and specified engine RPM in accordance with application. See «EGR SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
4. Operate engine with engine coolant temperature less than minimum temperature and specified RPM. No vacuum reading should be obtained when operated with engine coolant temperature less than minimum temperature.
5. Operate engine at normal operating temperature and specified RPM. See «EGR SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. A low vacuum reading should be obtained.
6. On all models except Turbo, disconnect hose from the "R" port of EGR vacuum modulator. (Scheme 137)
7. Using additional hose, connect "R" port directly to intake manifold. High vacuum reading should be obtained at specified engine RPM. See «EGR SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
8. To check EGR valve, apply vacuum directly to EGR valve with engine idling. Engine should run rough or stall. If system did not operate as described, each component should be tested.

EGR SPECIFICATIONS

EGR Vacuum Modulator

1. EGR vacuum modulator may be a 2-port or 3-port type depending on application. On 2-port models, disconnect hoses from vacuum modulator. Plug one end of vacuum hose connection on EGR vacuum modulator.
2. Apply air pressure through remaining port. Air should pass freely through air filter side of modulator. On 3-port models, disconnect all hoses. Block ports "P" and "R". Apply air pressure to port "Q". (Scheme 137) Air should pass through the air filter side of modulator freely.
3. On all models, operate engine at specified RPM. See «EGR VACUUM MODULATOR SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Repeat test procedures in steps 1) and 2). Strong resistance of airflow should be felt. Replace EGR vacuum modulator if resistance is not felt. Reconnect vacuum hoses to proper locations

EGR VACUUM MODULATOR SPECIFICATIONS

Scheme 137

Vacuum Switching Valve (VSV) (Non-Turbo)

1. Unplug VSV connector. Apply air to port "E". Air should pass through air filter. Apply battery voltage to VSV terminals. (Scheme 138)and (Scheme 139). Apply air pressure to port "E". Air should not pass through air filter. Disconnect battery terminals.
2. Using ohmmeter, measure resistance between both terminals of valve assembly. Replace valve if resistance is not within specification. See «VACUUM SWITCHING VALVE (VSV) SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.

VACUUM SWITCHING VALVE (VSV) SPECIFICATIONS

Vacuum Switching Valve (VSV) (Turbo)

1. Disconnect VSV connector. (Scheme 141) Apply air pressure to port "E". (Scheme 139) Air should pass through port "F".
2. Connect battery to VSV terminals. Apply air pressure to port "E". On Celica, air should pass through air filter. On Land Cruiser, no air should pass through port "F".
3. On Celica, using ohmmeter, check for continuity between terminals and VSV body. Replace unit if continuity exists. Using ohmmeter, measure resistance between both terminals of valve assembly. Replace valve if resistance is not within specification. See «VACUUM SWITCHING VALVE (VSV) SPECIFICATIONS»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.

Scheme 138

Scheme 139

Scheme 140

Scheme 141

Scheme 142

FUEL EVAPORATION

Note. (Scheme 143)and (Scheme 144) to identify evaporative emission control systems and operating parameters.

Fuel Odor Or Gas Leaks

Check for disconnected or cracked fuel vapor line or defective components in system. Check all lines and fittings. Check operation of system.

Fuel Tank Or Expansion Tank Deformed

Check for clogged canister, defective vacuum relief filler cap or restricted hoses.

Rough Engine Operation

Check vacuum hose between vacuum solenoid valve (if equipped) and intake manifold for damage or loose connections. Check for malfunctions in all valves. Ensure all vacuum hoses are tight and in good condition.

Bimetallic Vacuum Switching Valve (BVSV)

1. Drain engine coolant. Remove BVSV. Connect hose to top port. Place valve in water that is less than 95°F (35°C). Blow air into hose. Ensure valve is closed.
2. Heat water to 129°F (54°C). Blow air into hose. Ensure valve is open. If valve is not open, replace valve. Apply liquid sealer to threads of valve before installing. Fill cooling system. If BVSV does not operate as described, replace valve.

Charcoal Canister

1. Check for clogged filter and/or stuck check valve by blowing low pressure compressed air into canister tank port. Ensure air flows freely out of other canister ports.
2. Blow air into canister purge port. Ensure air does not flow out of any other port.

Restrictor

Remove hoses from restrictor and remove restrictor from vehicle. Blow air through both sides to ensure there is no blockage. Replace restrictor if airflow is blocked in either direction.

Maintenance

1. Inspect fuel tank, canister, vacuum relief filler cap, lines and hoses for damage, leaks and deterioration every 60,000 miles or every 6 years. Replace gasket in vacuum relief filler cap.
2. To clean charcoal canister filter, remove hoses from canister and apply 43 psi (3 kg/cm 2 ) air pressure to fuel tank port. Hold other top ports closed. Ensure that no carbon comes out of bottom port of canister.

Scheme 143

Scheme 144

Fixed Orifice

Visually inspect hose and connections for cracks, leaks or other damage. Clean deposits from orifice with solvent and blow out with compressed air

PCV Valve

Remove PCV valve. Attach hose to PCV valve. Blow air from cylinder head side of valve. Ensure air passes through easily. Blow air from intake manifold side. Ensure air passes through with some restriction. If PCV valve does not function as described, replace PCV valve.

Dashpot Control System (1.6L)

1. Engine must be at normal operating temperature. Check idle speed and adjust if necessary. Remove cap, filter and separator from dashpot. (Scheme 145)
2. Start engine. Maintain engine speed at specified testing RPM. See «DASHPOT TESTING RPM»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Plug Vacuum Transmitting Valve (VTV) hole with your finger. (Scheme 145)
3. Release throttle. Dashpot should be extended and dashpot setting RPM should be as specified. See «DASHPOT TESTING RPM»(/toyota/celica/t180-1989-1993/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. If idle speed is incorrect, adjust dashpot. (Scheme 146)
4. To check VTV operation, run engine at dashpot testing RPM for a few seconds. Plug the VTV hole with your finger. Release throttle. Uncover plugged hole. Engine should return to idle in about one second.
5. Install dashpot separator, filter and cap. Install filter with coarser surface facing outward.

DASHPOT TESTING RPM (1.6L)

Scheme 145

Scheme 146

See also:
• TURBINE SHAFT END & RADIAL PLAY
• FUEL DELIVERY