System/component Tests - Efi Mitsubishi Sigma pre-I

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 G - TEST W/CODES .

Wastegate Actuator Operation Test

Apply a pressure of 9.2 psi to wastegate actuator to ensure actuator rod moves. DO NOT apply more than 10.3 psi to wastegate actuator or attempt to adjust wastegate valve.

Barometeric Pressure Sensor

See the TESTS W/CODES in this section.

Coolant Temperature Sensor

1. Remove coolant temperature sensor from intake manifold. Place end of sensor in water. DO NOT allow sensor to touch container. Terminal connector portion of sensor should be .12" (3.0 mm) above water.
2. Gradually heat water and read resistance values across terminal connectors. See «COOLANT TEMPERATURE SENSOR RESISTANCE»(/mitsubishi/sigma/pre-i-1988-1989/remont/testing-diagnostics/#systemcomponent-tests-efi) table. If not within specifications, replace sensor. COOLANT TEMPERATURE SENSOR RESISTANCE Temperature: °F (°C) Resistance: Ohms 32 (0) 5900 68 (20) 2500 104 (40) 1100 176 (80) 300

Crank Angle Sensor (Van/Wagon)

1. Disconnect crankshaft angle sensor electrical connectors. Connect Test Harness (MD998464 ) between sensor and harness.
2. While cranking engine, measure output voltage between terminals No. 2 (Red test harness terminal) and No. 1 (Black test harness terminal). (Scheme 12) Output voltage should be 1.8-2.5 volts.
3. While cranking engine, measure output voltage between terminals No. 4 (White test harness terminal) and No. 1 (Black test harness terminal). Output voltage should be.2-1.5 volts.
4. If voltages are not to specification, check power supply and ground circuits. If power supply and ground circuits are okay, disassemble distributor and inspect.

Crank Angle Sensor (Montero)

Information is not available from manufacturer.

Crank Angle Sensor (All Others)

See FAULT CHARTS-PFI in the TESTS W/CODES article.

Scheme 12

Detonation Sensor

See the TESTS W/CODES article.

Note. EGR Sensors and Switches - For information on EGR related sensors and switches, See EXHAUST GAS RECIRCULATION (EGR) SYSTEM .

Idle Switch (Galant 2.0L DOHC, Mirage 1.6L & Sigma)

Disconnect TPS connector and connect Test Harness (MD998464 ) on idle switch side. Check continuity across test harness Black clip and ground. With accelerator pedal depressed, no continuity should be present. With accelerator pedal released, continuity should be present. Replace idle switch if not to specification.

Idle Switch (Galant 2.0L SOHC, Mirage 1.5L & Van/Wagon)

Disconnect the ISC servo connector. Check for continuity between terminal No. 3 and ground. (Scheme 13) With accelerator pedal depressed, no continuity should be present. With accelerator released, continuity should be present. If out of specification, replace ISC servo assembly.

Idle Switch (Montero)

Disconnect TPS connector. Using an ohmmeter, check continuity across TPS side of connector terminals No. 1 and 2. With accelerator pedal depressed, no continuity should be present. With accelerator pedal released, continuity should be present. Replace idle switch if not to specification. (Scheme 13)

Scheme 13

Scheme 14

1. Disconnect airflow sensor connector. On Mirage 1.6L, check intake air temperature sensor by measuring resistance between terminals No. 4 and 6 of sensor connector. For specifications, see «INTAKE AIR TEMPERATURE SENSOR RESISTANCE»(/mitsubishi/sigma/pre-i-1988-1989/remont/testing-diagnostics/#systemcomponent-tests-efi) table. (Scheme 14) Replace airflow sensor assembly if not to specification.
2. On all others, check intake air temperature sensor by measuring resistance between terminals No. 6 and 8. For specifications, see «INTAKE AIR TEMPERATURE SENSOR RESISTANCE»(/mitsubishi/sigma/pre-i-1988-1989/remont/testing-diagnostics/#systemcomponent-tests-efi) table. Replace airflow sensor assembly if not to specification. INTAKE AIR TEMPERATURE SENSOR RESISTANCE Temperature: °F (°C) Resistance: Ohms 32 (0) 6000 68 (20) 2700 176 (80) 400

Scheme 15

1. Disconnect motor position sensor connector and attach Test Harness (MD998464 ) to disconnected sensor connector only. Measure resistance between terminals No. 3 (White clip of test harness) and No. 1 (Black clip of test harness). Resistance should be 4000-6000 ohms.
2. Disconnect ISC motor connector and connect Test Harness (MD998464 ) to disconnected ISC motor connector. DO NOT connect test harness to ECU side of connector. (Scheme 15)
3. Attach ohmmeter between terminals No. 1 and 2 of motor position sensor. Connect a 6-volt DC power supply between terminals No. 1 (Black clip of test harness) and No. 2 (Red clip of test harness) of ISC motor connector to operate ISC motor.
4. Ensure motor position sensor resistance changes smoothly when motor is extended or retracted. Resistance should change from 500 ohms to approximately 4000-6000 ohms. If not to specification, replace ISC servo assembly.

Oxygen Sensor

Warm engine until coolant temperature is 185-205°F (85-95°C). Remove oxygen sensor connector. Connect voltmeter. (Scheme 16) With engine running at greater than 1300 RPM, measure output voltage. Voltage should be approximately one volt. If not, replace oxygen sensor.

Scheme 16

Scheme 17

1. Disconnect pressure hose from oil pump and connect in series a pressure gauge shutoff valve assembly capable of handling 250 psi (18 kg/cm 2 ), 2 tee-in pressure hoses and appropriate adapters. (Scheme 17)
2. Bleed air from system by grounding coil wire and cranking engine while turning steering wheel all the way from left to right 6 times. Start engine and turn steering wheel back and forth to raise fluid temperature to approximately 122-140°F (50-60°C).
3. With engine idling, disconnect connector from oil pressure switch and connect an ohmmeter to pressure switch terminal and engine ground.
4. Gradually close shutoff valve of pressure gauge to increase hydraulic pressure. Ensure pressure switch is closed (shows continuity) at a pressure of 213-248 psi (15-17 kg/cm 2 ).
5. Gradually open shutoff valve and ensure switch is open (no continuity) at 100-171 psi (7-12 kg/cm 2 ). Remove testing equipment. Bleed air from system by grounding coil wire and cranking engine while turning steering wheel all the way from left to right 6 times.

Throttle Position Sensor (Montero)

1. Disconnect TPS sensor connector. Using an ohmmeter, measure resistance between terminals No. 1 and 4. (Scheme 18) Resistance should be 3500-6500 ohms.
2. Check resistance between terminals No. 1 and No. 3. Operate throttle valve from closed to wide open throttle. Ensure resistance changes smoothly throughout entire range of approximately 500 ohms to 3500-6500 ohms. If not to specifications, replace TPS.

Scheme 18

1. Disconnect throttle position sensor connector. Check resistance between terminals No. 1 and 2. (Scheme 18) Total resistance should be 3500-6500 ohms.
2. Attach ohmmeter between terminals No. 3 and 2. Operate throttle valve from closed to wide open throttle. Ensure resistance changes smoothly throughout entire range of approximately 500 ohms at idle to 3500-6500 ohms at wide open throttle. If not to specification, replace TPS.

Throttle Position Sensor (Galant 2.0L DOHC, Mirage 1.6L & Sigma)

1. Disconnect TPS sensor connector. Connect Test Harness (MD998464 ) to disconnected sensor. Using an ohmmeter, measure resistance between Red clip and White clip of test harness. Resistance should be 3500-6500 ohms.
2. Check resistance between Red and Blue clips of test harness. Operate throttle valve from closed to wide open throttle. Ensure resistance changes smoothly throughout entire range of approximately 500 ohms at idle to 3500-6500 ohms at wide open throttle. If not to specification, replace TPS.

Throttle Position Sensor (Galant 2.0L SOHC & Mirage 1.5L)

1. Disconnect TPS sensor connector. Connect Test Harness (MD998478 ) to disconnected sensor. Using an ohmmeter, measure resistance between Red and Blue clip of test harness. Resistance should be 3500-6500 ohms.
2. Check resistance between Black and Blue clips of test harness. Operate throttle valve from closed to wide open throttle. Ensure resistance changes smoothly throughout entire range of approximately 500 ohms at idle to 3500-6500 ohms at wide open throttle. If not to specification, replace TPS.

Transmission Inhibitor Switch (Galant A/T & Sigma A/T)

Disconnect inhibitor switch connector at transmission. Operate inhibitor switch control lever to check continuity between terminals of inhibitor switch connector. (Scheme 19)

Scheme 19

Transmission Inhibitor Switch (Van/Wagon A/T)

Disconnect inhibitor switch connector at transmission. Operate inhibitor switch control lever to check continuity between terminals of inhibitor switch connector. (Scheme 20)

Scheme 20

Vehicle Speed Sensor Input Circuit (Sigma)

Raise front end of vehicle. Disconnect ECU harness. Place ohmmeter between terminal No. 17 of ECU and ground. (Scheme 21) Rotate wheels in forward direction and ensure ohmmeter indicates fluctuation between continuity and no continuity. If ohmmeter does not read properly, check circuit for open or shorted condition and/or bad vehicle speed sensor reed switch.

Scheme 21

Vehicle Speed Sensor Reed Switch (Sigma)

Connect an ohmmeter across reed switch terminals, rotate speedometer cable. (Scheme 22) Ensure ohmmeter readings fluctuate between continuity and no continuity 4 times for every one revolution of speedometer shaft rotation.

Scheme 22

Vehicle Speed Sensor Reed Switch (All Others)

Connect an ohmmeter across reed switch terminals, rotate speedometer cable. (Scheme 23)- (Scheme 26). Ensure ohmmeter readings fluctuate between continuity and no continuity when speedometer shaft is rotated.

Scheme 23

Scheme 24

Scheme 25

Scheme 26

Control Relay (Galant 2.0L DOHC, Mirage 1.6L, Montero & Sigma)

1. Remove cover under glove box and remove glove box. Disconnect control relay and 10-pin connector.
2. While applying battery voltage to terminal No. 10, ensure battery voltage is not present at terminal No. 4 and terminal No. 5. (Scheme 27) While applying battery voltage to terminal No. 10 and grounding terminal No. 8, ensure battery voltage is present at terminals No. 4 and 5.
3. While grounding terminal No. 6, ensure continuity is not present at terminals No. 2 and 3. While applying battery voltage to terminal No. 9 and grounding terminal No. 6, ensure continuity is present at terminals No. 3 and 2.
4. To check for short to ground, apply battery voltage to terminal No. 3, ensure there is no voltage at terminal No 2. While applying battery voltage to terminal No. 3 and grounding terminal No. 7, battery voltage should be present at terminal No. 2. Replace control relay if it fails test procedure.

Scheme 27

1. Disconnect electrical connector. Using an ohmmeter, ensure approximately 95 ohms of resistance is present between relay terminals No. 3 and 5, then 2 and 5. (Scheme 27)
2. Using an ohmmeter, ensure approximately 35 ohms of resistance is present between relay terminals No. 6 and 7. Ensure there is infinite resistance between relay terminals No. 1 and 4. Ensure there is infinite resistance between terminals No. 2 and 4.
3. Place positive lead of ohmmeter on terminal No. 6 and negative lead on terminal No. 8, ensure there is infinite resistance. Using an ohmmeter, place positive lead of ohmmeter on terminal No. 8 and negative lead on terminal No. 6, ensure there is zero resistance.
4. While grounding terminal No. 6 and applying battery voltage to terminal No. 8, ensure there is zero resistance between terminals No. 2 and 4.
5. While grounding terminal No. 6 and applying battery voltage to terminal No. 7, ensure there is zero resistance between terminals No. 1 and 4.

ISC Motor Resistance Test (Galant 2.0L SOHC & Mirage 1.5L)

Disconnect ISC motor connector. Using an ohmmeter, ensure resistance between terminals No. 1 and 2 is 5-35 ohms at a temperature of 68°F (20°C). (Scheme 28)

ISC Motor Resistance Test (Sigma)

1. At ISC motor connector, measure resistance between terminals No. 2 and 1 or terminals No. 2 and 3. (Scheme 28) Resistance should be 28-32 ohms at a temperature of 68°F (20°C).
2. Measure resistance between terminals No. 5 and 6, or between terminals No. 4 and 5 of ISC motor connector. Resistance should be 28-32 ohms at a temperature of 68°F (20°C).

ISC Motor Resistance Test (Galant 2.0L DOHC & Montero)

1. Disconnect the ISC servo connector. At ISC servo connector, measure resistance between terminal No. 2 and terminal No. 1 or terminal No.3. (Scheme 25) Standard value should be 28-32 ohms of resistance at a temperature of 68°F (20°C).
2. At ISC servo connector, measure resistance between terminal No. 5 and terminal No. 4 or terminal No. 6. Standard value should be 28-32 ohms of resistance at a temperature of 68°F (20°C).

ISC Motor Operation Test (Galant 2.0L SOHC & Mirage 1.5L)

Disconnect ISC motor connector. Connect four 1.5-volt DC batteries (6 volts total) between terminals No. 1 and 2 of ISC motor connector to operate ISC motor. (Scheme 28) If motor does not operate, replace ISC servo assembly.

ISC Motor Operation Test (Sigma)

Remove ISC motor. With 6 volts applied to terminals No. 2 and 5 of the connector, apply and remove a ground in sequence to terminals No. 3 and 6, No. 1 and 6, No. 1 and 4, No. 3 and 4, and No. 3 and 6. Reverse grounding sequence. If motor does not operate when grounding any of the mentioned terminals, replace ISC motor. (Scheme 28)

ISC Motor Operation Test (Galant 2.0L DOHC, Mirage 1.6L & Montero)

Disconnect ISC motor connector. Connect Test Harness (MD998463 ). Connect 6 volts to White or Green clip of test harness. Apply an electrical ground in sequence to test harness clips Blue and Yellow, Red and Yellow, Red and Black, Blue and Black, Blue and Yellow. Reverse grounding sequence. Motor is okay if it vibrates during testing.

Scheme 28

FUEL DELIVERY

Note. For Fuel System pressure testing, see BASIC TESTING article.

Scheme 29

1. Mark and remove vacuum hoses from solenoid valve. Disconnect wiring harness. Connect a vacuum pump to nipple where Black vacuum hose was connected and leave connected throughout testing procedure. (Scheme 29)
2. Apply vacuum to ensure vacuum leaks. Plug nipple where Blue-striped hose was connected and apply vacuum to ensure vacuum holds. Remove plug from Blue-striped hose nipple. Apply battery voltage to one terminal of valve and ground the other. Apply vacuum to ensure vacuum holds.
3. Using an ohmmeter, check resistance across terminals of solenoid. Resistance should be 36-46 ohms at a temperature of 20°C (68°F).

Fuel Injectors Operating Check

Using a stethoscope, check the operating sound of injectors during engine cranking or idling. Ensure operational sound increases when engine RPM is increased.

Fuel Injector Resistance Check (Galant, Mirage 1.5L, Montero, Sigma & Van/Wagon)

With injector electrical connector disconnected, measure resistance between injector terminals. Resistance should be 13-16 ohms at a temperature of 68°F (20°C).

Fuel Injector Resistance Check (Mirage 1.6L)

With injector electrical connector disconnected, measure resistance between injector terminals. Resistance should be 2-3 ohms at a temperature of 68°F (20°C).

IGNITION SYSTEM

Note. For basic ignition checks, see the BASIC TESTING article.

Galant (Fed.), Mirage (Fed.), Montero (A/T), Sigma & Van/Wagon

1. Disconnect Green-striped hose from throttle body and connect vacuum pump to hose end. Plug nipple where hose was connected to throttle body. When engine is cold, 122°F (50°C) or less and at idle, apply vacuum to disconnected hose. If idle does no change and vacuum bleeds down, system is okay.
2. When engine is hot, 205°F (95°C), and at idle, apply 1.8 in. Hg vacuum. If idle does not change and vacuum holds, system is okay.
3. Using a vacuum pump, apply 7.7 in. Hg vacuum. If idle becomes unstable or engine stalls (and vacuum holds), system is okay.

Galant (Calif.), Mirage (Calif.) & Montero (M/T)

1. Connect a vacuum tee into Green-striped hose from EGR valve and connect vacuum pump to vacuum tee. When engine is cold, 68°F (20°C) or less and at idle, snap throttle open to race engine. If no change in vacuum reading on vacuum pump gauge is detected, system is okay.
2. When engine is hot, 158°F (70°C) and at idle, snap throttle open to race engine. On Montero, if vacuum increases to 6 in. Hg or higher, system is okay.
3. Using vacuum pump, apply specified vacuum to open EGR valve. See «EGR VALVE SPECIFICATIONS»(/mitsubishi/sigma/pre-i-1988-1989/remont/testing-diagnostics/#systemcomponent-tests-efi) table. If idle becomes unstable or engine stalls, system is okay.

EGR Control Solenoid Valve

1. Label and disconnect vacuum hoses and wiring harness from solenoid valve. Connect a vacuum pump to vacuum nipple where Green-striped vacuum hose was connected.
2. Apply battery voltage to one terminal of solenoid and ensure vacuum does not hold. While applying battery voltage to one terminal and grounding the other, ensure vacuum holds.
3. Using an ohmmeter, measure resistance between the terminals of solenoid valve. At room temperature, a reading of 36,000-44,000 ohms should be present. Replace solenoid if not to specifications.

EGR Temperature Sensor

1. Remove EGR temperature sensor. Place EGR temperature sensor in water. While increasing water temperature, measure resistance between terminals.
2. At a temperature of 122°F (50°C), a resistance of 60,000-80,000 ohms should be present. At a temperature of 212°F (100°C), a resistance of 11,000-14,000 ohms should be present. Replace EGR temperature sensor if there is a significant resistance difference from specifications.

EGR Thermovalve

1. Disconnect vacuum hoses from thermovalve and connect a hand vacuum pump to a nipple of thermovalve. At a temperature of 122°F (50°C), vacuum should not hold.
2. On Montero, at a temperature of 149°F (65°C), vacuum should hold. On all other models, at a temperature of 176°F (80°C), vacuum should hold.

EGR Valve

1. Remove EGR valve and check it for sticking, deposits of carbon and damage. Clean with solvent if necessary.
2. Connect a hand vacuum pump to EGR valve. Apply maximum amount of vacuum to keep EGR valve closed. See «EGR VALVE SPECIFICATIONS»(/mitsubishi/sigma/pre-i-1988-1989/remont/testing-diagnostics/#systemcomponent-tests-efi) table. Ensure air does not flow thru EGR ports of valve.
3. Apply specified EGR valve opening vacuum. See «EGR VALVE SPECIFICATIONS»(/mitsubishi/sigma/pre-i-1988-1989/remont/testing-diagnostics/#systemcomponent-tests-efi) table. Ensure air flows thru EGR ports of valve. Replace valve if necessary. EGR VALVE SPECIFICATIONS Application Closed: In. Hg Open: In. Hg Galant & Sigma 1.7 7.5 Mirage 1.8 7.7 Montero 2.8 11 Van/Wagon 1.9 6.7

System Test (Galant & Montero)

1. Disconnect Red-striped vacuum hose running from throttle body to purge control solenoid valve at throttle body. Connect a hand vacuum pump to disconnected vacuum hose. Plug nipple on throttle body where vacuum hose was removed.
2. With engine coolant temperature 140°F (60°C) or less and engine idling, apply 14 in. Hg vacuum. Vacuum should hold. Raise engine speed to 3000 RPM and again apply 14 in. Hg vacuum. Vacuum should hold.
3. With engine coolant temperature 158°F (70°C) or more and engine idling, apply 14 in. Hg vacuum. Vacuum should hold. Turn engine off. Start engine and within 3 minutes of starting engine, apply vacuum. Vacuum should bleed down.
4. With engine running for more than 3 minutes after starting, raise engine speed to 3000 RPM and apply 15 in. Hg. of vacuum. Vacuum should hold momentarily and then bleed down. NOTE: On all models except Montero, in step 4) vacuum should bleed down continuously if altitude is 7200 Ft. or higher, or intake air temperature is 122°F (50°C) or lower.

System Test (Sigma)

1. Disconnect Red-striped vacuum hose running from throttle body to purge control solenoid valve at throttle body. Connect a hand vacuum pump to disconnected vacuum hose. Plug nipple on throttle body where vacuum hose was removed.
2. With engine coolant temperature 104°F (40°C) or less and engine idling, Apply 16 in. Hg vacuum. Vacuum should hold. Raise engine speed to 3000 RPM and again apply 16 in. Hg vacuum. Vacuum should hold.
3. With engine coolant temperature 176°F (80°C) or more and engine idling, apply 16 in. Hg vacuum. Vacuum should hold. Turn engine off. Start engine and within 3 minutes of starting engine, apply vacuum. Vacuum should bleed down.
4. With engine running for more than 3 minutes after starting, raise engine speed to 3000 RPM and apply 16 in. Hg vacuum. Vacuum should hold momentarily and then bleed down. NOTE: In Step 4), vacuum should bleed down continuously if altitude is 7200 Ft. or higher, or intake air temperature is 122°F (50°C) or lower.

Purge Control Solenoid Valve (Non-Turbo Engines)

1. Remove Red-striped hose at purge control solenoid valve and connect a hand vacuum pump to solenoid nipple. Apply vacuum to solenoid valve, vacuum should hold and not bleed down.
2. With vacuum applied, disconnect electrical connector and apply positive battery voltage to one solenoid connector and ground the other. Vacuum should bleed down when voltage is applied. Using an ohmmeter, check resistance across solenoid terminals. Reading should be 36-44 ohms at 68°F (20°C).

Purge Control Solenoid Valve (Turbo Engines)

1. Remove Red-striped hose at purge control solenoid valve and connect a hand vacuum pump to solenoid nipple. Apply vacuum to solenoid valve, vacuum should not hold.
2. With vacuum applied, disconnect electrical connector and apply positive battery voltage to one solenoid connector and ground the other. Vacuum should hold when voltage is applied. Using an ohmmeter, check resistance across solenoid terminals. Reading should be 36-44 ohms at 68°F (20°C).

PCV Valve

Remove PCV valve and insert thin screwdriver into threaded end of valve to ensure plunger moves.

See also:
• BASIC TESTING
• G - TEST W/CODES
• COOLANT TEMPERATURE SENSOR RESISTANCE