Engine Controls - System/component Tests - Efi Toyota Supra A70

INTRODUCTION

Note. Prior to testing separate components or systems, it is highly recommended that all procedures listed in BASIC TESTING be performed. Since many computer controlled and monitored components will set a trouble code if they malfunction, it is also recommended that self diagnosis be performed. See TESTS W/CODES .

INTAKE AIR INDUCTION SYSTEM CHECK - NON-TURBO

1. The ECU uses inputs from engine RPM ("NE" terminal) and throttle position sensor to operate the air control valve vacuum switching valve ground ("VSV1" terminal). Vacuum switching valve allows vacuum to operate the air control valve. When current flows to vacuum switching valve, air control valve shuts and increases intake runner length.
2. To test system, check for loose or leaking vacuum connections. Start engine. At idle, the air control valve (on intake chamber) should be in open position. Slowly increase engine speed to 5000 RPM. Air control valve should close (vacuum applied).
3. If air control valve did not close in step 2), check for vacuum signal to air control valve, and use hand-held vacuum pump to check air control valve diaphragm for leaks. Replace air control valve if diaphragm is bad.
4. If air control valve is okay, check for voltage between ECU terminal "VSV1" (Light Green/Black wire) and ground. Remove glove box. Turn ignition on, with engine off. With ECU connector plugged in, insert digital voltmeter probe from back side of ECU connector. Ensure there are 0.5-2.0 volts between "VSV1" and ground.
5. If voltage is not present, check wiring between ECU and air control valve vacuum switching valve. NOTE: Air control valve vacuum switching valve is mounted on top of vacuum reservoir (Light Green/Black and Black/Red wires), in left side of engine compartment. Black/Red wire is powered through EFI main relay.
6. Ensure there are 0.5-2.0 volts between ECU terminals "VSV1" and "E1" (Brown wire). If voltage is not present, check voltage between ECU and body ground. See PIN VOLTAGE CHART S article if unsure of terminal identification.
7. If power circuit is okay, check vacuum switching valve. Unplug vacuum switching valve connector. Ground one valve terminal and apply 12 volts to other terminal. Air should flow through valve ports. Remove 12 volt source. Air should flow from one port to air filter. Replace valve if defective.

INITIAL CHECKS

1. Check air intake for clogged air cleaner, collapsed air hoses, or cracked air intake hoses.
2. Inspect exhaust system for restricted exhaust. Check for leaks or clogging between cylinder head and turbocharger inlet. Also check between turbocharger outlet and exhaust pipe.
3. 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 move aside. Disconnect actuator hose. Using a pressure gauge and pump, apply 9.4 psi (65 kPa) of pressure to actuator hose. (Scheme 53) Check that rod moves.0098" (.25 mm) or more. If less, replace turbocharger assembly.

Scheme 53

IMPELLER WHEEL ROTATION

Disconnect air cleaner hose. Grasp edge of impeller wheel and turn it. Verify that it turns smoothly. If it does not turn or if it turns with drag, 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 54

1. Ensure all intake air hoses are connected. Place pressure hose and "T" with actuator hose that goes to intake manifold. (Scheme 54) Start engine.
2. On Supra with M/T, accelerate vehicle with throttle valve fully open. Measure pressure when engine RPM is over 2500 RPM. On Supra with A/T, drive vehicle from standing start with transmission in "L" with throttle valve fully open. Measure pressure with engine running more than 3500 RPM. See TURBOCHARGER PRESSURE table. TURBOCHARGER PRESSURE SUPRA Model Pressure psi (kPa) Automatic Transmission 4.8-6.0 (33-41) Manual Transmission 5.5-7.5 (38-52)
3. If pressure is less than specification, first check intake air and exhaust systems for leaks. If there are no leaks, replace turbocharger assembly. If pressure is above specification, first check if the actuator hose is disconnected or cracked. If not, replace turbocharger assembly.

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

Scheme 55

Scheme 56

1. Unplug connector from turbocharger pressure sensor. On Supra Turbo, pressure sensor is under hood on top of left side shock tower.
2. Turn ignition on with engine off. Turbo meter needle should move to upper position. Ground terminal No. 2 on the wiring harness side. (Scheme 55) Meter needle should move to lower position. If meter does not respond as described, go to step 3).
3. Remove instrument cluster. Measure turbo meter resistance. (Scheme 56) Resistance should be 72 ohms. Replace turbo meter if resistance is not as specified.
4. To check turbo meter drive circuit, see the TURBO METER DRIVE CIRCUIT SPECIFICATIONS table. All measurements are made between the terminal and ground. Tests are made with instrument panel wiring harnesses disconnected.
5. Unplug the pressure sensor. Ground the 3 terminals on the wiring harness side of connector "E". There should be continuity.

Scheme 57

TURBO METER DRIVE CIRCUIT SPECIFICATIONS

AIRFLOW METER & SENSOR TEST

Turn ignition off. Unplug wiring connector from airflow meter. Note terminal identification. (Scheme 60)or (Scheme 61). Using an ohmmeter, measure resistance between specified terminals. On Supra Turbo models, use ONLY an analog ohmmeter. Replace airflow meter if not within specification. See AIRFLOW METER RESISTANCE SPECIFICATIONS table.

Scheme 58

Scheme 59

Scheme 60

Scheme 61

AIRFLOW METER RESISTANCE SPECIFICATIONS

CAMSHAFT POSITION SENSOR TEST

For Supra Turbo camshaft position sensor, see IGNITION SYSTEM in this article.

COOLANT TEMPERATURE SENSOR TEST

1. Ensure ignition is off. Unplug connector from sensor. For sensor location, see appropriate illustration in THEORY/OPERATION article in this section.
2. Using ohmmeter, check resistance between sensor terminals. Replace sensor if resistance is not within specification at specified temperature. (Scheme 62)

Scheme 62

EGR GAS TEMPERATURE SENSOR TEST

Remove sensor from side of EGR valve. Place threaded end of sensor and thermometer in container of oil. (Scheme 63) Attach ohmmeter to sensor terminals. Heat the oil and note the resistance at specified temperature. See EGR TEMPERATURE SENSOR SPECIFICATIONS table. Replace sensor if not within specification.

EGR TEMPERATURE SENSOR SPECIFICATIONS

Scheme 63

KNOCK SENSOR TEST

On models equipped with knock sensor, diagnosis is in trouble code No. 52 and 53 charts. For trouble code charts, see TESTS W/CODES article in this section.

NEUTRAL/START SWITCH TEST

Unplug switch connector at transmission or transaxle. Note terminal identification. (Scheme 64) Using ohmmeter, check for continuity at specified terminals with gearshift in correct range. See NEUTRAL/START SWITCH SPECIFICATIONS table.

NEUTRAL/START SWITCH SPECIFICATIONS

Scheme 64

OXYGEN SENSOR FEEDBACK VOLTAGE TEST

1. Warm engine to normal operating temperature. Connect an analog type voltmeter to engine check connector "VF1" (or "VF") and "E1" terminals. (Scheme 65) To test oxygen sensor feedback voltage (Scheme 66)
2. If analog voltmeter does not respond correctly as described in (Scheme 66) test procedure, O2 sensor can also be checked in conventional manner with digital volt/ohm meter (10 meg. ohm resistance). Attach DVOM to "OX" terminal of engine check connector under hood.
3. An O2 sensor going bad will have very few fluctuations on the analog voltmeter "VF" circuit, and the DVOM will remain near.50 volts on the "OX" circuit.
4. Supra models are equipped with a main O2 sensor, sub-oxygen sensor (California Non-Turbo Models), and an O2 sensor heater.

Note. Trouble code Nos. 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.

Scheme 65

Scheme 66

SUB-OXYGEN SENSOR TEST - CALIF. NON-TURBO MODELS

1. Inspection is required when trouble code No. 27 exists. Clear trouble codes. See CLEARING TROUBLE CODES under TESTS W/CODES article in this section. Warm engine to normal operating temperature. CAUTION: DO NOT exceed 62 MPH or trouble code will be canceled.
2. Drive vehicle at 50 MPH or less for at least 5 minutes in 4th or 5th gear (M/T) or "D" range (A/T). Fully depress accelerator pedal for at least 10 seconds with engine RPM at least 3000 RPM.
3. Stop engine and turn ignition off. Repeat previous steps and note if trouble code No. 27 exists again. If trouble code exists again, check sub-oxygen sensor circuit for continuity, shorts or grounds. Replace sub-oxygen sensor if circuit is okay.

OXYGEN SENSOR HEATER TEST

1. Unplug O2 sensor connector. Using ohmmeter, measure resistance between sensor terminals. Replace sensor if resistance is not within 5-6 ohms at 68°F (20°C). (Scheme 67)
2. A trouble code No. 21 is also an indicator of a problem in O2 sensor circuit. Trouble code No. 21 will set if O2 sensor heater circuit opens or shorts to ground on "HT" wire from sensor to ECU.

Scheme 67

THROTTLE POSITION SENSOR (TPS) TEST

Turn ignition off. Unplug electrical connector at TPS on throttle body. Note terminal identification. (Scheme 68) 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 SUPRA

Scheme 68

Scheme 69

TURBOCHARGER VACUUM SWITCHING VALVE (VSV) TEST

1. Using ohmmeter, check continuity between both terminals of turbocharging pressure VSV connector. (Scheme 70) Resistance should be 24-30 ohms. Replace VSV if no continuity exists.
2. Check that no continuity exists between VSV case (body) and each terminal. If continuity exists, replace VSV.
3. Check that air does NOT flow from pipe "E" to pipe "F". If air flows through from pipe "E" to pipe "F", replace VSV. Apply battery voltage across terminals. Air should flow from pipe "E" to pipe "F". If not, replace VSV.

Scheme 70

VEHICLE SPEED SENSOR (ANALOG TYPE) TEST

Remove combination meter from instrument cluster. Connect ohmmeter between terminals "A" and "B". (Scheme 71) Rotate meter shaft and note reading. Ohmmeter should deflect from 0 (zero) to infinity as shaft is rotated.

Scheme 71

CIRCUIT OPENING RELAY TEST

To check circuit opening relay (Scheme 72)& 21. Supra models circuit opening relay is located behind right kick panel, above ECU. Replace relay if defective.

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 for wire color.

Scheme 72

Scheme 73

EFI MAIN RELAY TEST

To test EFI main relay (Scheme 74) Replace relay if defective. Supra EFI main relay is located in the relay bank, on left front fenderwell.

Scheme 74

FUEL DELIVERY TEST

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

FUEL PUMP RELAY & RESISTOR TEST

To test relay and resistor (Scheme 75) Replace relay or resistor if defective.

FUEL PUMP RELAY LOCATION

Scheme 75

Scheme 76

FUEL INJECTOR RESISTOR (TURBO MODELS) TEST

1. Turn ignition off. Unplug injector solenoid resistor. Check resistance between terminal + B and other terminals. (Scheme 77) Resistance should be 3 ohms.
2. If resistance is not as specified, replace solenoid resistor. Supra fuel injector resistor is located on the right shock tower. If resistance is good, check power feed to fuel injector resistor.

Scheme 77

FUEL INJECTORS TEST

1. Turn ignition off. Unplug each injector connector. Measure resistance across both terminals. See FUEL INJECTOR RESISTANCE SPECIFICATIONS table. FUEL INJECTOR RESISTANCE SPECIFICATIONS Model (1) Resistance Supra Turbo 2-4 Supra Non-Turbo 13.8 (1) Measured at 68°F (20°C).
2. To check injector spray pattern and volume, relieve fuel system pressure and remove injectors from engine. Disconnect fuel hose from fuel filter outlet. Use Fuel Injection Kit (09268-41080) to tee fuel injector between fuel filter and fuel pressure regulator. (Scheme 78)& 27.
3. Place injector into a graduated container. Place vinyl tube on end of injector to prevent fuel from splashing out.
4. Hook up Fuel Injector Tester (09842-30070) or trigger box with appropriate resistor to fuel injector. Turn ignition on, with engine off.
5. Connect jumper wire to engine check connector terminals "FP" and "+B" to pressurize fuel system. For engine check connector locations (Scheme 65) Connector terminals are marked on inside of check connector cover. Fuel pump check connector is 2-wire connector near airflow meter in left rear corner of engine compartment (White/Black and Green wires).
6. 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 table. FUEL INJECTOR VOLUME SPECIFICATIONS Model Volume Cu. In. (cc) Supra 7M-GE 4.2-5.2 (69-85) 7M-GTE 6.2-7.0 (101-114) Difference Between Each Injector.3 (5)
7. 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.

Scheme 78

Scheme 79

FUEL PRESSURE-UP SYSTEM TEST (TURBO)

1. Ensure coolant temperature sensor, air temperature sensor (in airflow meter) and circuits are operating correctly. See specific SENSOR or SWITCHES testing in this article. Supra fuel pressure-up vacuum switching valve is located at the lower side of the intake manifold runners.
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. To test (Scheme 80)

Scheme 80

Scheme 81

1. Connect a tachometer to engine (to monitor needle fluctuations). See ADJUSTMENTS 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 81)
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 82) Check that fuel-cut points and fuel return points are within specifications. See DECELERATION FUEL-CUT & FUEL RETURN RPM table.

Scheme 82

DECELERATION FUEL-CUT & FUEL RETURN RPM

COLD START INJECTOR TEST

1. Cold start injector and cold start injector time switch are both fed current from ignition switch during cranking. Cold start injector ground circuit is controlled by cold start injector time switch. To test cold start injector, unplug cold start injector wiring harness. Check resistance between terminals of injector Resistance should be 2-4 Ohms. Replace injector if defective.
2. To check cold start injector spray pattern and leakage, relieve fuel system pressure. Remove cold start injector from vehicle.
3. Install fuel hose to injector. If original hose is too short, use Fuel Injection Kit (09268-41045) to extend the hose length and add a union. (Scheme 83)& 32.
4. Place container under cold start injector. Turn ignition on, with engine off. Connect jumper wire to engine check connector terminals "FP" and "+B" to pressurize fuel system. For engine check connector locations (Scheme 65) Fuel pump check connector is 2-wire connector near airflow meter in left rear corner of engine compartment (White/Black and Green wires). CAUTION: Perform cold start injector connector test in shortest possible time.
5. Connect probes of Fuel Injector Tester (09842-30070) to battery. Connect other end of tester to cold start injector. (Scheme 83)& 32.
6. Ensure fuel spray is an even cone shape. 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 83

Scheme 84

Note. Cold start injector is controlled by cold start injector time switch when ignition switch is turned on. See WIRING DIAGRAMS in this section.

COLD START INJECTOR TIME SWITCH TEST

1. Unplug cold start injector time switch connector. For cold start injector time switch location, see the appropriate illustration in the THEORY/OPERATION article.
2. Using ohmmeter, check resistance between terminals "STA" & "STJ" at appropriate temperature. (Scheme 85) See COLD START INJECTOR TIME SWITCH SPECIFICATIONS table. There should be continuity between terminal "STA" and ground. Replace switch if not within specification.

Note. "STA" terminal is fed current from ignition switch during cranking. "STJ" goes to cold start injector.

COLD START INJECTOR TIME SWITCH SPECIFICATIONS

Scheme 85

IDLE SPEED CONTROL (ISC) SYSTEM TEST

1. Listen for "clicking" sound after engine is shut off. If no sound is heard, check ISC valve and wiring.
2. To check wiring circuit, turn engine off. Unplug ISC valve connector. Turn ignition on with engine off. Connect voltmeter between "B1" and "B2" (2 center wires) terminals of wiring harness connector. (Scheme 86) Battery voltage should be present. If not, check wiring between ISC valve and EFI main relay.
3. If voltage in step 2) is okay, check wiring between ISC valve and ECU. With ignition on and engine off, there should be battery voltage at "ISC1", "ISC2", "ISC3" and "ISC4" terminals of ECU. Measure voltage at wiring side of connector (connector plugged in) with digital voltmeter. Also check ECU ground.
4. To check ISC valve, turn ignition off. Unplug ISC valve connector. Measure resistance between ISC valve terminals. (Scheme 86) See ISC VALVE RESISTANCE SPECIFICATIONS table. Replace ISC valve if resistance is not as specified. ISC VALVE RESISTANCE SPECIFICATIONS Terminals Ohms B1 to S1 or S 10-30 B2 to S2 or S4 10-30 NOTE: Before removing ISC valve, drain coolant from cooling system. Remove both coolant by-pass hoses. On Supra Turbo only, ensure check valve and seal washer are installed in air intake chamber.
5. To check valve operation, remove ISC valve from vehicle. Apply battery voltage to terminal "B1" and terminal "B2". (Scheme 86) Repeatedly ground terminals "S1", "S2", "S", "S4" and "S1" in sequence. Valve closes. Remove ground wires.
6. Apply battery voltage to terminals "B1" and "B2". Repeatedly ground terminals "S4", "S", "S2", "S1" and "S4" in sequence. Valve should move toward open position. Replace valve if it failed to operate properly.

Scheme 86

IGNITION SYSTEM DIAGNOSTIC CODES TESTS (NON-TURBO)

Note. ECU is programmed to detect ignition problems. Checking for trouble codes can speed up your diagnosis. If ECU detects a problem a diagnostic code will be set in memory. For information on system self-diagnostic capabilities and how to retrieve codes, see TESTS W/CODES article in this section.

CODE 12 (NO RPM SIGNAL)

ECU will store trouble code No. 12 in memory if it does not receive signal from either "NE" pick-up coil (RPM) or "G" pick-up coil (crank position) within 2 seconds of engine cranking.

CODE 13 (NO RPM SIGNAL)

ECU will store trouble code No. 13 in memory if it does not receive signal "NE" pick-up coil (RPM) when engine speed is above 1000 RPM.

CODE 14 (IGNITION SIGNAL PROBLEM)

ECU will store trouble code No. 14 in memory if it does not receive "IGF" (ignition detection) signal 6-8 times in succession.

SPARK TEST (NON-TURBO)

1. On models with integral ignition coil, disconnect spark plug wires. Remove spark plugs. Install spark plugs to each spark plug wire. Ground spark plugs. Spark plug tester can also be used. (Scheme 91)
2. On models with an external ignition coil, disconnect high-tension (coil) wire from distributor. Hold wire about 1/2" away from ground. CAUTION: To prevent gasoline from being injected, do not crank engine for more than 2 seconds.
3. On all models, crank engine and check for spark. If spark does not occur, check ignition coil, ignitor and distributor connections.
4. If connections are good, check resistance of high-tension wires. If resistance is not within specification, replace wires. See IGNITION HIGH-TENSION WIRE RESISTANCE table in this article. If wires are okay, go to next step.
5. Check power supply to ignition coil and ignitor. Place ignition switch in "ON" position. Check for voltage at ignition coil positive terminal. If voltage is not present, check wiring between ignition switch, coil, and ignitor. If voltage is present, go to next step.
6. Check ignition coil resistance. See IGNITION COIL RESISTANCE TESTS in this article. If ignition coil resistance is not as specified, replace coil. If coil resistance is within specification, go to next step.
7. Check pick-up coil resistance. See PICK-UP COIL RESISTANCE TEST in this article. If resistance is within specification, go to next step. If pick-up coil resistance is not as specified, replace pick-up coil. NOTE: On some models, it is necessary to replace entire distributor assembly.
8. Check air gap between reluctor and pick-up coil. See PICK-UP COIL AIR GAP CHECK in this article. If air gap is incorrect, replace distributor assembly.
9. If air gap is correct, check ignition "IGT" signal from ECU. See appropriate trouble code No. 14 chart in TESTS W/CODES article. If "IGT" signal is okay, replace ignitor.

IGNITION HIGH-TENSION WIRE RESISTANCE

PRIMARY COIL RESISTANCE (NON-TURBO)

1. Disconnect ignition coil so it is isolated from remainder of system. Using ohmmeter, measure resistance between coil positive (+) and negative (-) terminals. (Scheme 87)
2. If primary resistance is not within specification, replace ignition coil. See IGNITION COIL RESISTANCE table. If resistance is within specification, proceed to SECONDARY COIL RESISTANCE.

SECONDARY COIL RESISTANCE (NON-TURBO)

1. Disconnect ignition coil so it is isolated from remainder of system. Using an ohmmeter, measure resistance between coil positive (+) terminal and coil tower. See IGNITION COIL RESISTANCE table. (Scheme 88)
2. If resistance is not within specification, replace ignition coil. If resistance is within specification, proceed to PICK-UP COIL RESISTANCE TEST.

IGNITION COIL RESISTANCE (1)

Scheme 87

Scheme 88

PICK-UP COIL RESISTANCE TEST (NON-TURBO)

1. Measure resistance of pick-up coil between terminals "G1" and "G(-)", "G2" and "G(-)", and between "NE" and "G(-)". (Scheme 89)
2. If resistance is not within specification, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

PICK-UP COIL RESISTANCE (1)

Scheme 89

PICK-UP COIL AIR GAP CHECK (NON-TURBO)

1. Using a flat, non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 90)
2. Air gap should be within specification. See PICK-UP COIL ADJUSTMENT table. If air gap is not within specification, replace distributor.

PICK-UP COIL ADJUSTMENT

Scheme 90

IGNITION SYSTEM DIAGNOSTIC CODES TESTS (TURBO)

Note. ECU is programmed to detect ignition problems. Checking for trouble codes can speed up your diagnosis. If ECU detects problem, diagnostic code will be set in memory. For information on system self-diagnostic capabilities and how to retrieve codes, see TESTS W/CODES article in this section.

ECU will store trouble code No. 12 in memory if it does not receive signal from either "NE" pick-up coil (RPM) or "G" pick-up coil (crank position) within 2 seconds of engine cranking.

ECU will store trouble code 13 in memory if it does not receive signal from "NE" pick-up coil (RPM) when engine speed is above 1000 RPM.

ECU will store trouble code 14 in memory if it does not receive "IGF" (ignition detection) signal 6-8 times in succession.

Scheme 91

1. Remove duct between air cleaner and intake plenum air connector. Disconnect cruise control, accelerator, and throttle cables (automatic transmission only).
2. Remove 6 hoses from idle speed control pipe. Remove 2 bolts and idle speed control pipe from intake plenum air connector. Remove oxygen sensor wire from clamp. Disconnect hose from PCV pipe. Remove 2 bolts and disconnect PCV pipe with hoses from cylinder head covers and throttle body.
3. Disconnect hose from intake plenum air connector. Remove 2 bolts, loosen clamps, and remove intake plenum air connector. Remove oil filler cap. Remove 5 nuts from "TOYOTA TURBO" labeled ignition coil pack cover, and lift off cover.
4. Remove nut and disconnect No. 1 and No. 2 wires from ignition coil and clamp. Move ignition coil pack with bracket out of the way and remove all spark plug wires from spark plugs.
5. Remove all spark plugs. Install oil filter cap. Install spark plug wires onto the original 6 spark plugs or use several high output spark testers along with spark plugs. (Scheme 91)
6. If spark plug testers are available, install one on each wire of separate coil packs along with one spark plug to other spark plug lead per coil pack.
7. If spark testers are not available, install all 6 spark plug wires to the 6 removed spark plugs. Ground each spark plug and/or spark tester securely. CAUTION: Ignition coil primary or ignitor circuit damage can result if each spark plug and/or spark plug tester is not securely grounded.
8. Disconnect solenoid resistor block and cold start injector connector. Cold start injector is on bottom of air intake chamber. Solenoid resistor block is on top of right side shock tower (4-wire connector).
9. Crank engine and check for consistent Blue spark across plug gaps. If all spark plugs and/or spark testers do not fire, check ignition feed to coil pack and ignitor circuits. See IGNITION FEED CIRCUIT TEST under IGNITION COIL in this article.
10. Verify that camshaft sensor signals are received by ECU. See IGNITOR TEST in this article. Also, verify camshaft sensor moves when engine is cranked.
11. If only one or 2 spark plugs and/or spark plug testers show an inconsistent spark across the gap, test that particular coil pack for ignition coil primary resistance as well as spark plug wire resistance. See IGNITION COIL and IGNITION HIGH-TENSION WIRE RESISTANCE table in this article.

IGNITION HIGH-TENSION WIRE RESISTANCE

IGNITION SYSTEM CONNECTION CHECKS (TURBO)

1. With ignition switch in the "OFF" position, check connections of all 3 ignition coil primary circuits. Check for loose connections or corrosion. Tighten and/or clean connections as required.
2. Check connection on primary feed wire to coil and ignitor. If loose or corroded connections exist, correct them and repeat SPARK TEST.
3. If no spark output is observed or no problems were located and resolved in this test, proceed to IGNITION FEED CIRCUIT TEST under IGNITION COIL in this article.

IGNITION COIL FEED CIRCUIT TEST (TURBO)

1. Disconnect ignition feed 2-pin connectors from coil packs. Turn ignition switch to the "ON" position. Measure voltage between terminal No. 1 (battery feed) and ground. (Scheme 92)
2. There should be 12 volts present with ignition on. If reading indicates a problem, repair open circuit between ignition switch and battery feed to coil pack. If no battery feed problems are detected, go to PRIMARY COIL RESISTANCE.

Scheme 92

PRIMARY COIL RESISTANCE (TURBO)

Using an ohmmeter, measure resistance between positive and negative terminals of ignition coils. (Scheme 93) Replace ignition coil if resistance is not to specification. See IGNITION COIL RESISTANCE table. If no problems are detected, proceed to IGNITION COIL GROUND TEST.

Note. It is not possible to check ignition coil secondary resistance.

Scheme 93

IGNITION COIL GROUND TEST (TURBO)

Turn ignition off. Disconnect ignition coil connectors. Using an ohmmeter, ensure there is no continuity between ignition coil terminals and ground. If there is continuity, replace ignition coil. If no problems are detected, proceed to IGNITION OPERATIONAL CHECK.

IGNITION COIL RESISTANCE

FEED TO IGNITOR TEST (TURBO)

1. Turn ignition off. Unplug ignition module 6-pin connector. Ignition module 6-pin module connector is located next to alternator. Turn ignition switch to the "ON" position. Check for 12 volts between terminal No. 3 and ground. (Scheme 94)
2. Reconnect 6-pin connector. If feed voltage is not present, repair open in wiring harness and retest system. If feed circuit is okay, proceed to PICK-UP COIL RESISTANCE.

Scheme 94

PICK-UP COIL RESISTANCE (TURBO)

To test resistance of the 3 pick-up coils, disconnect camshaft sensor 4-wire connector. Measure resistance from terminal "G(-)" to terminals "G1", "G2" and "NE". (Scheme 95) Resistance of each pick-up coil should be 140-180 ohms. If resistance is not as specified, replace camshaft position sensor assembly. If pick-up coil resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

Scheme 95

PICK-UP COIL AIR GAP CHECK (TURBO)

1. Using flat, non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 96) Air gap should be within.008-.016" (.20-.40 mm).
2. If air gap is incorrect, replace camshaft position sensor assembly. If air gap clearance is within specification, proceed to IGNITOR TEST.

Scheme 96

IGNITOR POWER TRANSISTOR CHECK (TURBO)

1. Turn ignition off. Unplug ignition module 4-pin connector. Disconnect each ignition coil pack 2-pin connector.
2. Turn ignition switch to "ON" position. Connect ohmmeter between terminal No. 2 of third ignition coil and ground. Using a 3-volt dry cell battery, apply 3 volts to terminal No. 2 of 4-pin connector. With 3 volts applied, check that ohmmeter indicates momentary continuity. (Scheme 97)
3. Connect ohmmeter between terminal No. 2 of first ignition coil and ground. Apply 3 volts to terminal No. 4 of 4-pin connector. With 3 volts still applied to terminal No. 4, also apply 3 volts to terminal No. 2. Check that ohmmeter indicates momentary continuity. (Scheme 97)
4. Connect ohmmeter between terminal No. 2 of second ignition coil and ground. Apply 3 volts to terminal No. 3 of 4-pin connector. With 3 volts still applied to No. 3, also apply 3 volts to terminal No. 2. Ensure ohmmeter indicates momentary continuity. (Scheme 97)

Scheme 97

Scheme 98

DASHPOT CONTROL SYSTEM TEST

1. Engine must be at normal operating temperature. Ensure idle speed is correct. Raise engine speed to 3000. Pinch vacuum hose between dashpot and Vacuum Transmitting Valve (VTV). Release throttle valve. Ensure dashpot is set and engine RPM is 2000. (Scheme 99)or (Scheme 100).
2. To check VTV, run engine at 3000 RPM. Pinch vacuum hose between VTV and dashpot. Release throttle. Release pinched hose. Engine should return to idle within about 1 second. To check VTV off of vehicle (Scheme 103) If adjustment is necessary (Scheme 101)or (Scheme 102).

Scheme 99

Scheme 100

Scheme 101

Scheme 102

Scheme 103

EGR SYSTEM TEST

1. Ensure modulator filter is clean and in good condition prior to performing test. Clean filter with compressed air as required. Disconnect vacuum hose from EGR valve.
2. Using a "T" connector, connect a vacuum gauge in EGR valve vacuum line. Check that engine starts and runs at idle. This ensures proper seating of EGR valve.
3. Different vacuum switching valves are used depending on model. (Scheme 107)or (Scheme 108). The Bi-Metallic Vacuum Switching Valve (BVSV), Vacuum Switching Valve (VSV) and EGR modulator can be checked with engine coolant below minimum temperature and specified engine RPM in accordance with application. See EGR SPECIFICATIONS table.
4. Operate engine with engine coolant below minimum temperature and specified RPM. No vacuum reading should be obtained when operated with engine coolant below minimum temperature.
5. Operate engine at normal operating temperature and specified RPM. See EGR SPECIFICATIONS table for specified engine RPM. A vacuum reading of 2.6 in. Hg should be obtained. On all other models, a low vacuum reading should be obtained.
6. On Supra non-turbo models, ensure vacuum is not present at idle. Disconnect hose from the "R" port of EGR vacuum modulator. Using additional hose, connect "R" port directly to intake manifold. High vacuum reading should be obtained at specified engine RPM. See EGR SPECIFICATIONS table. NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
7. To check EGR valve, apply vacuum directly to EGR valve with engine idling. Engine should run rough. If system did not operate as described, each component should be tested.

EGR SPECIFICATIONS

Scheme 104

1. EGR vacuum modulator may be a 2-port or 3-port 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 104) 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 table. Repeat previous test procedure 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

VACUUM SWITCHING VALVE (VSV) (TURBO) TEST

1. Unplug VSV connector. Connect battery to VSV terminals. (Scheme 105) Apply air pressure to port "E". Air should escape from air filter. Disconnect battery terminals.
2. Apply air pressure to port "E". Air should now escape from port "F". Using ohmmeter, check for continuity between terminals and VSV body. Replace unit if incorrect airflow or continuity exists.
3. Using ohmmeter, measure resistance between both terminals of valve assembly. On Supra model, resistance should be 38-44 ohms at 68(0)F (20(0)C). On all other models resistance should be 30-50 ohms at 68°F (20°C). Replace valve if resistance is not within specification.

Scheme 105

VACUUM SWITCHING VALVE (VSV) (NON-TURBO) TEST

1. Unplug VSV connector. Connect battery to VSV terminals. (Scheme 106) Apply air pressure to port "E". Air should escape from port "F". Disconnect battery terminals.
2. Apply air pressure to port "E". Air should not escape from port "F". Using ohmmeter, check for continuity between terminals and VSV body. Replace unit if incorrect airflow or continuity exists.
3. Using ohmmeter, measure resistance between both terminals of valve assembly. Resistance should be 38-44 ohms at 68°F (20°C). Replace valve if resistance is not within specification.

Scheme 106

Scheme 107

Scheme 108

FUEL ODOR OR GAS LEAKS

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

Canister is clogged, vacuum relief filler cap is defective or hoses are clogged or kinked.

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.

BI-METALLIC VACUUM SWITCHING VALVE (BVSV) TEST

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. Refill engine with coolant. If BVSV does not operate as described, replace valve.

CHARCOAL CANISTER CHECK

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

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.