System/component Tests - 4-cyl Mazda 323 BF

INTRODUCTION

Note. Prior to testing separate components or systems, it is highly recommended that all procedures listed in BASIC TESTING - 4-CYL article 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 appropriate TESTS W/CODES article.

AIR BY-PASS VALVE

Remove air by-pass valve. Connect vacuum pump to port "A" of valve. Apply vacuum and blow from port "B". (Scheme 5) Verify air flows at 9.8-15.7 in. Hg (MX-6 and 626) or 3.94-14.57 in. Hg (323). If air does not flow, replace air by-pass valve.

Scheme 5

MX-6 & 626

Engine must be cool. Disconnect hose "A" from solenoid valve and connect pressure tester. (Scheme 6) Warm engine to normal operating temperature. Increase engine speed to 4000 RPM and verify boost pressure is a positive pressure above 0 psi (0 kg/cm 2 ). If boost pressure is not within specification, proceed to following tests as necessary.

323

Disconnect air hose to wastegate valve. Connect pressure gauge. (Scheme 6) Connect tachometer to engine. Warm engine to normal operating temperature. Increase engine speed to 4000 RPM and verify boost pressure is minimum of 0.28 psi (0.02 kg/cm 2 ). If boost pressure is not within specification, proceed to following tests as necessary.

Scheme 6

COMPRESSOR & TURBINE WHEEL DEFLECTION

Allow engine to cool. Disconnect negative battery cable. Remove air funnel. Turn compressor and turbine wheel. Replace turbocharger if wheel does not turn freely or touches housing.

INTERCOOLER

Remove intercooler. Inspect for cracks, restriction or damage. Replace if necessary.

OIL PASSAGE INSPECTION

Engine must be cool. Remove oil return pipe. Verify carbonized oil is not blocking oil passage in turbocharger or oil return pipe. Replace turbocharger and return pipe if necessary.

MX-6, 323 & 626

Start engine and run at 2000 RPM. Lift air cleaner upper case and push measuring plate completely open. Warning buzzer should sound and engine speed should drop or engine should stall.

1. Turn ignition switch to "ON" position. Disconnect hose from pressure switch and attach compressed air source to pressure switch. (Scheme 7) Adjust compressed air pressure to 10.4-11.5 psi (0.73-0.81 kg/cm 2 ). Warning buzzer should sound. If buzzer does not sound, go to next step.
2. Turn ignition switch to "ON" position. Apply air pressure of 10.4-11.4 psi (0.73-0.81 kg/cm 2 ) to pressure switch and check voltage at Blue/Green and Black terminals with connector connected. If voltage is not correct, proceed to next step. See «PRESSURE SWITCH VOLTAGES»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl) table. PRESSURE SWITCH VOLTAGES Condition Light/Green Terminal Black Terminal Compressed Air Applied 12 Volts 0 Volts Compressed Air Not Applied 0 Volts 0 Volts
3. Turn ignition switch to "OFF" position. Disconnect pressure switch connector. Apply air pressure of 10.4-11.5 psi (0.73-0.81 kg/cm 2 ) to pressure switch and check continuity between terminals. (Scheme 7) See «PRESSURE SWITCH CONTINUITY»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl) table.

PRESSURE SWITCH CONTINUITY

Scheme 7

Disconnect small air tube from air hose. Disconnect solenoid valve connector. (Scheme 8) Blow through air tube and verify air does not flow. If air does flow, replace solenoid valve and turbocharger as an assembly. Apply 12 volts to solenoid valve. Blow through air tube and verify air does pass. If air does not pass with 12 volts applied, replace solenoid valve and turbocharger as an assembly.

Scheme 8

WASTEGATE

1. Engine must be cool. Remove exhaust manifold insulator and side insulator. Remove hose connected to actuator and connect compressed air source with pressure gauge. (Scheme 9)
2. Apply compressed air to actuator. Apply 8.5 psi (0.6 kg/cm 2 ) on MX-6 and 626 and 0-8.5 psi (0.49-0.60 kg/cm 2 ) on 323. Verify actuator rod moves when connecting and disconnecting hose supplying compressed air.

Scheme 9

A/C SWITCH

See A/C CUT-OUT CONTROL SYSTEM under RELAYS, SOLENOIDS, MOTORS & MODULES.

B2600i & MPV 2.6L

1. Pull rubber boot back from airflow sensor connector. Check terminal voltages. (Scheme 10) See «B2600i & MPV 2.6L AIRFLOW SENSOR TERMINAL VOLTAGES»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl) table.
2. If voltages are not correct, check wiring for open or short circuit. If wiring is okay, check the burnoff operation. If ECU control of burnoff operation is okay, replace the airflow sensor.

B2600i & MPV 2.6L AIRFLOW SENSOR TERMINAL VOLTAGES

Scheme 10

B2600i & MPV 2.6L (Burnoff Operation)

1. Perform this test if airflow sensor voltage test is incorrect. Disconnect negative battery cable. Reconnect negative battery cable.
2. Bring engine to normal operating temperature. Pull back rubber boot from airflow sensor connector. Run engine for 3 minutes at about 2000 RPM in Neutral.
3. Turn ignition off. Check voltage at airflow sensor Green/Orange wire and at terminal 2K of ECU. There should be 0 volts just after ignition is turned off. There should be about 8-12 volts momentarily, 2-5 seconds after ignition switch is off.
4. If voltages are as specified, replace the airflow sensor. If voltages are not as specified, check voltage at ECU terminals 2E, 2I and 2J and related wiring.

Inspect airflow meter for damage and ensure measuring plate moves smoothly. (Scheme 11) Disconnect airflow meter connector. Measure resistance using AIRFLOW METER TERMINAL RESISTANCE table.

AIRFLOW METER TERMINAL RESISTANCE

Scheme 11

Testing

1. Remove vacuum hose on sensor. Turn ignition on and check voltage between terminal "A" and ground, and "B" and ground. Observe voltmeter while applying and releasing vacuum.
2. Voltage at terminal "B" should be about 4.5-5.5 volts. Voltage at terminal "A" should be less than 1.5 volts. If voltage at terminals "A" or "B" is not correct, check wiring harness. If voltage fluctuates, replace atmospheric pressure sensor.
3. Measure voltage between terminal "D" and ground. Depending on altitude, voltage at terminal "D" should be 3.5-4.5 volts at sea level and 2.5-3.5 volts at 6500 feet. If voltage at terminal "D" is incorrect, replace atmospheric pressure sensor. (Scheme 12)

Scheme 12

BRAKE LIGHT SWITCH

Disconnect brake light switch connector. Measure resistance between terminals of brake light switch. With brake pedal released, resistance should be infinite. With brake pedal depressed, resistance should be zero ohms.

CLUTCH SWITCH

Remove connector from switch. Connect ohmmeter to switch terminals. Check that continuity exists with clutch pedal depressed and no continuity exists with pedal released. Replace switch if continuity is not correct.

COOLANT THERMOSENSOR

1. Remove thermosensor. Place thermosensor in container of heated coolant with thermometer.
2. Connect ohmmeter to thermosensor terminals. Note resistance at specified temperatures. See «COOLANT THERMOSENSOR RESISTANCE»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl) table. Replace if not within specification.

COOLANT THERMOSENSOR RESISTANCE

COOLANT TEMPERATURE SWITCH

1. Remove switch from radiator. Place switch in container of heated coolant with thermometer.
2. Connect ohmmeter to switch terminals. Note temperature at which continuity exists between switch terminals. Continuity should exist with coolant temperature above 63°F (17°C). Replace switch if not within specification.

CRANK ANGLE SENSOR

See IGNITION TESTING in BASIC TESTING - 4-CYL article.

EGR POSITION SENSOR (MX-6 & 626)

For testing procedures, see EGR SYSTEM under EMISSION SYSTEMS and SUB-SYSTEMS.

All Except B2600i & MPV

1. Connect a voltmeter between control unit and ground. Start engine. Check voltage at terminals using appropriate ELC UNIT VOLTAGE chart. (Scheme 14)or (Scheme 15).
2. If voltages are incorrect, check the appropriate circuit. If voltages are okay, replace ELC.

B2600i & MPV

1. Remove the ELC from behind left side of instrument panel. Check voltage at terminals of ELC connector using ELC UNIT VOLTAGE chart. (Scheme 13)
2. If voltages are incorrect, check the appropriate circuit. If voltages are okay, replace ELC.

Scheme 13

Scheme 14

Scheme 15

Unplug idle switch connector. Check continuity between switch and ground. See IDLE SWITCH CONTINUITY table. (Scheme 16) If switch does not pass test, check harness for open or short circuits. Replace idle switch if necessary.

IDLE SWITCH CONTINUITY

Scheme 16

1. Disconnect 1-pin connector at idle switch. Check for continuity between switch and ground.
2. With throttle fully closed, there should be continuity. With throttle open, there should be no continuity. If switch is not correct, replace throttle body.

Idle switch is part of throttle position sensor, see ADJUSTMENTS - 4-CYL article.

INHIBITOR SWITCH (A/T)

Remove connector from switch. Connect ohmmeter to appropriate switch terminals. See WIRING DIAGRAMS - CEC article for wire identification. Continuity should exist with gearshift in Park and Neutral. No continuity should exist in other ranges.

Disconnect intake air temperature sensor connector. Measure resistance of sensor using INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. (Scheme 17)or (Scheme 18).

Scheme 17

INTAKE AIR TEMPERATURE SENSOR RESISTANCE

Remove connector from switch. Connect ohmmeter to switch terminals. Check that continuity exists with transmission in Neutral and no continuity exists in other ranges. Replace switch if continuity is not correct.

1. Disconnect connector near transmission. Place transmission in Neutral position. Resistance across switch should be infinite.
2. Place transmission in any gear. Resistance across switch should be zero ohms. If necessary, replace switch.

OXYGEN SENSOR (O2)

1. Warm engine to operating temperature. Run engine at fast idle. Disconnect O2 sensor. Connect a high impedance voltmeter between O2 sensor and ground.
2. Observe voltmeter while rapidly accelerating and decelerating engine speed. Replace O2 sensor, if voltage is not .5-1.0 volt while accelerating and 0-.4 volt while decelerating. Ensure new oxygen sensor has anti-seize compound applied to threads. Tighten sensor to 22-36 ft. lbs. (29-49 N.m).

POWER STEERING SWITCH

1. Start engine and allow to idle. Remove connector from switch. Connect ohmmeter to switch terminals. Turn steering wheel from side to side and note continuity reading.
2. Continuity should exist with front wheels turned but should not exist with wheels straight ahead. Replace switch if continuity is not correct.

PULSATION DAMPER

Start engine and run at idle. Pulsation damper is located at end of fuel rail. Place finger over pulsation damper and ensure damper pulsates. Replace pulsation damper if no operation exists.

STOPLIGHT SWITCH

Stoplight switch is located at top of brake pedal. Switch should show continuity when brake pedal is depressed.

All 4-Cyl Models

See ON-VEHICLE ADJUSTMENTS article for checking and adjustment procedures.

VEHICLE SPEED SENSOR

See PIN VOLTAGE CHARTS article.

1. Disconnect White 2-pin connector near battery. Measure resistance between Blue wires.
2. With transaxle in 5th gear, resistance should be infinite. With transaxle in any other gear, resistance should be zero ohms.

Operation

The A/C clutch relay is opened (disengages A/C clutch), for 7 seconds during the following conditions: blower and A/C switch on, transmission in gear, clutch pedal released and throttle opened more than half way.

1. Turn A/C, blower and ignition switches on. DO NOT start engine. Shift transmission into a drive gear. Open throttle fully. Listen for A/C clutch disengaging and reengaging after 7 seconds.
2. If system does not test as indicated, check operations of related switches and relays. See «PIN VOLTAGE CHARTS»(ref-18105) article.

AIR INJECTION SOLENOIDS

For all related control solenoids, see SECONDARY AIR INJECTION under EMISSION SYSTEMS & SUB-SYSTEMS.

AIR INDUCTION CONTROLS

For all related control solenoids, see AIR INDUCTION.

CIRCUIT OPENING RELAY

See FUEL CONTROL CIRCUIT in BASIC TESTING - 4-CYL article for test procedures.

COIL WITH IGNITOR

See IGNITION SYSTEM in BASIC TESTING - 4-CYL article for test procedures.

EGR SOLENOID (MX-6 & 626)

For testing procedures, see EGR SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS.

Operation (Non-Turbo)

1. Using stethoscope, listen for normal "clicking" sound at each injector during idle and acceleration.
2. Start engine and slowly increase engine speed. Using stethoscope, check that operating sound of secondary injectors occurs above 3500 RPM. If clicking sound is not heard, check crank angle sensor resistance, wiring from crank angle sensor to ECU and EGI main fuse.

Operation (Turbo)

Information not available.

Injector Resistance

Remove electrical connector from injector. Using ohmmeter, measure resistance between injector terminals. Replace injector if resistance is not within specifications.

FUEL INJECTOR RESISTANCE

HOT START RELAY

See HOT START ASSIST in FUEL SYSTEM section.

B2600i, MVP, MX-6 & 626

1. Ensure main relay clicks when ignition is turned on and off.
2. If no sound is heard, unplug relay. Apply 12 volts to terminal A and ground terminal B. (Scheme 18)
3. Use ohmmeter to check terminal continuity. Terminals C-D should have continuity with 12 volts applied. There should be no continuity with no voltage applied. If relay does not respond as described, replace the main relay.

Scheme 18

1. Ensure a clicking sound is heard at main relay when turning ignition on and off. (Scheme 19) Disconnect main relay. Apply 12 volts to terminal No. 5 and ground terminal No. 6.
2. Ensure continuity between main relay terminals No. 1 to 2 and 3 to 4, when voltage is applied. There should be no continuity when voltage is not applied.

Scheme 19

PRESSURE REGULATOR CONTROL SOLENOID

1. Unplug vacuum hose from pressure regulator control solenoid. Blow through solenoid from port A. Ensure air flows through port B. (Scheme 20)
2. Unplug solenoid valve connector. Connect 12 volts and ground to solenoid terminals. (Scheme 20) Blow through solenoid from port A. Air should exhaust through the valve air filter. Replace solenoid valve if it does not pass test.

Scheme 20

PURGE CONTROL SOLENOIDS

For testing procedures, see FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

TICS SOLENOID

See AIR INDUCTION.

VRIS SOLENOID

See AIR INDUCTION.

WASTEGATE SOLENOID

See AIR INDUCTION.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING - 4-CYL article.

Injector Fuel Leakage

1. Remove dynamic chamber, if necessary. Loosen delivery pipe attaching bolts. Remove delivery pipe. Using wire, secure injectors tightly onto delivery pipe. CAUTION: Ensure injectors are securely tied to delivery pipe. If not properly secured, fuel may spray from loose connections.
2. Install jumper wire between 2 terminals of fuel pump test circuit connector. See «BASIC TESTING - 4-CYL»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl) for test connector location. Turn ignition on. Check that no fuel leakage exists at injectors. After 5 minutes, only a slight amount of fuel leakage is acceptable.

Note. Injector delivery volume information is not available for B2600i and MPV with 2.6L engine.

Injector Delivery Volume

1. Using wire, secure injectors tightly onto delivery pipe. Install hose on injector. Install Injector Checker (49 B092 953) on injector. (Scheme 21)
2. Install jumper between 2 terminals of fuel pump test circuit connector. See «BASIC TESTING - 4-CYL»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl) for test connector location. Turn ignition on. Connect injector checker to battery voltage. Note injector volume within 15 seconds.
3. Replace injectors which do not meet volume specifications. Check primary and secondary injectors in the same manner.

INJECTOR VOLUME SPECIFICATIONS

Scheme 21

Fuel Pump Relay Control

On all except B2600i, MPV and RX7, see FUEL SYSTEM in BASIC TESTING - 4-CYL section. On B2600i and MPV, see appropriate TESTS W/CODES and WIRING DIAGRAMS - CEC articles.

BAC Valve

1. Remove the BAC valve from the throttle body. Blow air through the valve from port A and ensure air comes out port B when valve is cold. (Scheme 22)
2. Place BAC valve in hot water (more than 176°F or 80°C) for one minute. Blow air through valve from port A. No air should come out of port B. Replace BAC valve if it fails the test.
3. Measure resistance of Idle Speed Control (ISC) valve at 2 wire connector of BAC valve. Resistance should be between 6.3-9.9 ohms, at normal operating temperature. If not, replace BAC valve.

Scheme 22

1. Remove BAC valve hose from throttle body. (Scheme 23) Blow air through port "A". Ensure air flows when valve is cold. If not, replace BAC valve.
2. Measure resistance of Idle Speed Control (ISC) Valve at 2 wire connector of BAC valve. Resistance should be between 5-20 ohms, at normal operating temperature. If not, replace BAC valve.

Scheme 23

System Inspection

1. Operate engine to warm temperature. Ensure air temperature is above 113°F (45°C). Shut engine off. Connect voltmeter to pressure regulator control solenoid valve (Blue/Black wire on B2600i & MPV, White/Red on MX-6 and 626, or Brown wire on 323). (Scheme 24)
2. Start engine and note voltage. Voltage should be below 2 volts for 1-4 minutes after engine is started, then increase to approximately 12 volts after 1-4 minutes.

Scheme 24

Pressure Regulator Control Solenoid Valve

1. Disconnect hose from solenoid. Blow through port "A". see scheme 21 Air should flow from port "B". Remove connector from valve.
2. Apply battery voltage and ground to proper terminals. see scheme 21 Blow through port "A". Air should flow through air filter.

Intake Air Temperature Sensor

Using ohmmeter, measure sensor terminal resistance at specified temperature. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. Replace sensor if not within specification.

INTAKE AIR TEMPERATURE SENSOR RESISTANCE

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC DIAGNOSTIC PROCEDURES.

KNOCK CONTROL

Note. If secondary (spark voltage) is available and no problems with knock control system are present, see TESTS W/CODES article. If no trouble codes are available or problem still exists, see PIN VOLTAGE CHARTS article.

Knock Control System (MX-6 Turbo & 626 Turbo)

1. Connect Self-Diagnostic Checker (49 H018 9A1) and ground test connector lead. Turn ignition on.
2. Tap lightly on right engine hanger. Ensure monitor lamp on checker flashes. If not, connect a good knock sensor and recheck.
3. If test results remain the same, replace knock control unit.

Knock Control System (323 Turbo)

1. With engine at normal operating temperature, check ignition timing. Ensure voltage at ECU connector terminal No. 1U is approximately 12 volts.
2. Disconnect single wire service connector at ECU. Tap engine hanger and note ignition timing. If timing does not retard, replace knock sensor and retest.
3. If timing retards, connect single wire service connector and retest. If timing retards, replace knock control unit. If timing does not, system is okay.

EMISSION SYSTEMS & SUB-SYSTEMS

Note. For complete vacuum schematics, see VACUUM DIAGRAMS article.

Air Pump

1. With engine at normal operating temperature, inspect all hose connections and belt tension.
2. Stop engine. Disconnect line from air pump to air control valve at the valve. Install Pressure Gauge Set (49 2113 010B) to the line. (Scheme 25) Connect tachometer to engine.
3. Start engine. Operate engine at idle and note pressure reading. Reading should exceed 1.7 psi (.12 kg/cm 2 ). Replace pump if not within specification.

Scheme 25

Converter Air Line Check Valve

Disconnect intake manifold-to-converter check valve hose at the check valve. Install tachometer and start engine. Accelerate engine to 1500 RPM. Check for exhaust leakage from check valve opening. Replace check valve if leakage exists.

Intake Manifold Check Valve

Disconnect air pump-to-air control valve air hose at the air pump. Install tachometer and start engine. Disconnect switching solenoid valve connector. Accelerate engine to 1500 RPM. Check for exhaust leakage at air control valve inlet fitting. (Scheme 26) Replace check valve if leakage exists.

Scheme 26

Scheme 27

Scheme 28

1. Operate engine to normal operating temperature. Stop engine and install tachometer. On turbo models equipped with Anti-Lock Brake Systems (ABS), disconnect and plug air hose and vacuum hose of air by-pass valve from the turbo. CAUTION: On turbo models with Anti-Lock Brake Systems (ABS), ensure air hose and vacuum hose of air by-pass valve are disconnected and plugged prior to removing air silencer-to-air control valve hoses.
2. On all models, disconnect air silencer-to-air control valve hose at air control valve. Place finger over air control valve outlet. Start engine and increase engine speed to 3750 RPM on turbo models or 1500-2500 RPM on non-turbo models. Note that air begins to flow at specified RPM.
3. Operate engine at idle. On turbo models, disconnect relief valve solenoid Blue connector. (Scheme 27) On non-turbo models, disconnect relief valve solenoid-to-air control valve hose. (Scheme 27)
4. Check that air flows from air control valve outlet above 1200 RPM on turbo models or at idle on non-turbo models. Reconnect vacuum hose or Blue connector.
5. Remove intake manifold-to-check valve hose. Disconnect hose at check valve on turbo models or intake manifold on non-turbo models. Place finger over opening.
6. On turbo models, disconnect hose at air control valve at air control valve. (Scheme 28) On non-turbo models, disconnect hose at switching solenoid valve. (Scheme 27)
7. With engine at idle, note that air flows from intake manifold fitting (non-turbo) or check valve (turbo). Replace air control valve if necessary. Reconnect all hoses.

Scheme 29

1. Install tachometer. Warm engine to normal operating temperature. Allow engine to idle. Connect Checker Light (49 F018 001) to Green connector. Check connector is located near air filter on non-turbo or intercooler on turbo. (Scheme 29)
2. Remove relief solenoid valve-to-air control valve hose at air control valve. Cover valve port with finger. Note that Green checker light activates and air flows at designated areas. See GREEN CHECKER LIGHT OPERATION table. NOTE: Checker light may occasionally turn off at approximately 1200 RPM. GREEN CHECKER LIGHT OPERATION Engine Condition Air Flow Light Operation Idle No On Non-Turbo (Above 3600 RPM) Yes Off Turbo (Above 4000 RPM) Yes Off Deceleration No On
3. Remove right seat and floor mat. Disconnect heat hazard sensor connector. Install jumper wire to terminals of connector to the ECU. Ensure Green checker light does not activate and air flows from valve port at any engine speed. Remove jumper wire. Install connector at heat hazard sensor.
4. Start engine. Increase engine speed, noting that Green checker light does not activate and air flows from valve port when engine speed exceeds 1000-1200 RPM.

Switching Solenoid Valve Signal Check

1. Install tachometer. Warm engine to normal operating temperature. Allow engine to idle. Connect Checker Light (49 F018 001) to Green connector. (Scheme 29)
2. Disconnect hose at air control valve. (Scheme 28) Cover valve port with finger and note that Red checker light activates and air is drawn into valve at designated areas. See «RED CHECKER LIGHT OPERATION»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl) table.

RED CHECKER LIGHT OPERATION

Split Air Solenoid Valve (M/T Models)

1. Connect voltmeter at Blue/Black wire terminal and ground of solenoid valve.
2. Turn ignition on. Place transmission in 5th gear and note voltage. Voltage should be below 2.5 volts in 5th gear and approximately 12 volts in all other gears.

Split Air Solenoid Valve (A/T Non-Turbo Models)

1. Connect voltmeter at Blue/Black wire terminal and ground of solenoid valve.
2. Place gearshift in "D" range. Remove oil pressure switch connector on side of transmission. Install jumper wire between connector and ground. (Scheme 30)
3. Turn ignition on and note voltage. Voltage should be below 2.5 volts with jumper wire installed or approximately 12 volts with jumper wire removed.

Scheme 30

Port Air Solenoid Valve (Turbo)

Install jumper wire between Blue wire terminal and ground of solenoid valve. Turn ignition on and listen for operating sound of solenoid valve. Replace valve if no operating sound is heard.

Port Air Solenoid Valve (Non-Turbo)

1. Install voltmeter between Blue wire terminal and ground of solenoid valve. Start engine. Allow to idle and note voltage reading. Voltage should be below 2.5 volts.
2. Open throttle halfway and note voltage. Voltage should be approximately 12 volts.

Note. Solenoid valve voltage will be constantly below 2.5 volts once vehicle has operated over 20,000 miles.

Relief Solenoid Valve (Non-Turbo)

1. Disconnect vacuum hoses from relief solenoid valve. Blow through port "B". (Scheme 31) Air should flow from air filter. Remove connector from solenoid valve.
2. Apply battery voltage and ground to proper terminals. (Scheme 31) Blow through port "B". Air should flow from port "A".

Scheme 31

Relief Solenoid Valve (Turbo)

1. Disconnect vacuum hoses from relief solenoid valve. Blow through port "A". (Scheme 31) Air should flow from port "B". Remove connector from solenoid valve.
2. Apply battery voltage and ground to proper terminals. (Scheme 31) Blow through port "A". Air should flow from air filter.

Switching Solenoid Valve

1. Disconnect vacuum hoses from switching solenoid valve. Blow through port "A". see scheme 29 Air should flow from port "B". Remove connector from solenoid valve.
2. Apply battery voltage and ground to proper terminals. see scheme 29 Blow through port "A". Air should flow from air filter.

System Inspection (B2600i & MPV 2.6L)

Check components of system and replace as necessary.

System Inspection (MX-6 & 626)

1. Start and warm engine to normal operating temperature. With engine idling, disconnect top hose from No. 1 purge control valve on charcoal canister. Install a vacuum gauge to hose. Increase engine speed to 2500 RPM. Ensure vacuum exceeds 5.9 in. Hg. If not, check coolant thermovalve. Remove vacuum gauge. Reconnect vacuum hose.
2. Disconnect vacuum hose from port "B" of No. 3 purge control valve. Connect vacuum gauge and hose to valve port. (Scheme 37) Accelerate engine to a speed greater than 1500 RPM. Note that vacuum is present at port. If vacuum is not present, check 3-way solenoid valve, No. 3 purge control valve, and terminal "2P" at ECU for poor connection.
3. Remove vacuum gauge and hose. Reconnect vacuum hose to purge control valve. Disconnect fuel tank hose from charcoal canister. Connect vacuum pump/gauge to hose. Try to apply vacuum to hose. Vacuum should not be held. If vacuum is held, check 3-way valve or fuel tank hose for blockage.

Scheme 32

Scheme 33

System Inspection (323)

1. Start and warm engine to normal operating temperature. With engine idling, connect voltmeter to the No. 1 3-way solenoid valve (Black/Yellow terminal). Voltage reading should be about 12 volts. If not, check solenoid and wiring to ECU.
2. Disconnect top hose from No. 1 purge control valve on charcoal canister. Place finger over open end of hose. Increase engine speed to 2000 RPM. Ensure vacuum is not created at hose. If vacuum is present, check No. 1 3-way solenoid valve and wiring to control unit. Remove finger from hose. Leave hose disconnected. Return engine to idle.
3. Disconnect neutral/safety switch connector on manual transaxle, or inhibitor switch connector on automatic transaxle. Voltage reading should be 1.5 volts.
4. Place finger over purge control valve hose. Increase engine speed to 2000 RPM. Vacuum should be created at hose end. If not, check No. 1 3-way solenoid valve and wiring to ECU.

Evaporation Line

Disconnect hose leading from charcoal canister to fuel tank. Connect a vacuum pump to the hose. Apply vacuum and note if vacuum is held. No vacuum should be held. If vacuum is held, test check and cut-valve and evaporation hose for blockage.

Check Valve (B2600 & MPV 2.6L)

Note direction of valve installation. Remove check valve. Blow air into both ends of valve. Air should flow through valve from charcoal canister side, but should not flow from airflow meter side (beveled end). Replace valve if defective.

Check & Cut Valve

1. Remove check and cut valve. Connect a pressure gauge with "T" fitting on nipple leading to fuel tank. Cap opposite nipple. (Scheme 34)
2. Blow through passage "A". When pressure gauge reads.14-.71 psi (.01-.05 kg/cm 2 ), valve should open. Remove "T" fitting and pressure gauge. Connect "T" fitting to bottom of valve. Blow through passage "B". When pressure gauge reads.78-1.0 psi (.06-.07 kg/cm 2 ), valve should open. Replace assembly if valve did not open at specified pressure.

Scheme 34

Coolant Thermovalve (MX-6 & 626)

1. Remove coolant thermovalve. Connect a piece of tubing to each nipple. Immerse valve in container of water. Insert thermometer and slowly heat water.
2. At temperature greater than 131°F (55°C), blow into one of the hoses. Air should pass through valve. If not, replace coolant thermovalve.

Scheme 35

Scheme 36

1. To check No. 1 purge control valve, remove hoses from charcoal canister. Attempt to blow through intake manifold port. Air should not pass. Attach vacuum pump/gauge to top port of purge control valve. Apply 4.3 in. Hg. Blow through intake manifold port. Air should flow through port. (Scheme 35) If not, replace valve.
2. The No. 2 purge control valve is an integral part of charcoal canister. Disconnect canister evaporation hose at line leading to fuel tank. Air should pass through valve under pressure and under vacuum, if valve is operating properly. (Scheme 36)
3. To test No. 3 purge control valve, disconnect hoses. Remove No. 3 purge control valve from vehicle. Connect vacuum pump/gauge to single port. Blow into port "A". Ensure air does not flow from port "B". (Scheme 37)
4. Apply about 3 in. Hg on MX-6 and 626 or 4 in. Hg on all others, to port. Blow into port "A". Air should flow through port "B". If air does not flow, replace purge control valve.

Scheme 37

Purge Control Solenoid Valve (B2600i & MPV 2.6L)

1. Engine must be normal operating temperature. Run engine at idle. Disconnect White vacuum hose from solenoid valve. No vacuum should be felt at valve. For valve locations (Scheme 38) If vacuum is felt at valve, go to step 2).
2. Unplug vacuum hoses from dynamic chamber and charcoal canister. Ensure no air flows through valve.
3. Unplug solenoid valve connector. Connect 12 volts and ground to solenoid valve terminals. (Scheme 38) Air should now flow through solenoid valve. If air does not flow, replace solenoid valve.

Scheme 38

Purge Solenoid (MX-6, 323 & 626)

1. Disconnect vacuum hose from solenoid. (Scheme 39) Blow through port "A". Ensure air exhausts through air filter.
2. Disconnect 2-wire connector from solenoid. Connect 12 volts to one terminal and ground the other terminal of solenoid. Blow air though port "A". Ensure air exhausts through port "B".

Scheme 39

3-Way Valve (323, MX-6 & 626)

Remove 3-way valve. Blow through valve from fuel tank port. Make sure air comes out of canister port. Block canister port. Air should exit vent port. Block canister port. Blow through vent port. If air exits fuel tank port, valve is functioning properly. (Scheme 40)

Scheme 40

PCV

No testing information is available. See VACUUM DIAGRAMS article for hose routing.

Scheme 41

Scheme 42

Scheme 43

1. Check all connectors, hoses and routings for cracks, leakage, or restrictions and repair as needed. Bring engine to normal operating temperature and run at idle. Remove and plug vacuum hose at EGR control valve. If engine runs rough, test EGR control valve.
2. Remove plug from vacuum hose at EGR control valve and connect vacuum gauge. Remove and plug vacuum hose at bottom of EGR modulator valve and connect a hose in its place. (Scheme 43) Increase engine speed to 2000 RPM and blow into hose. If no increase of vacuum is noted, test EGR modulator valve. Reinstall hoses to EGR modulator valve and EGR control valve.
3. Remove vacuum hose from EGR modulator valve marked No. 1 and connect vacuum gauge. Increase engine speed to 2500 RPM. Vacuum should be more than 5.9 in. Hg. Test EGR solenoid valve if vacuum is less. With vacuum gauge still installed, disconnect Green/Black wire of coolant temperature switch. Increase engine speed to 2500 RPM and ensure no vacuum is present. If vacuum is present, test EGR solenoid valve and Electronic Control Unit (ECU) at "2N" terminal.

MX-6 & 626 Turbo

1. Check all connectors, hoses and routings for cracks, leakage, or restrictions and repair as needed. Bring engine to normal operating temperature and run at idle. Remove and plug vacuum hose at EGR control valve. If engine runs rough, test EGR control valve.
2. Remove plug from vacuum hose and connect vacuum gauge. With engine at idle, vacuum should not be present. Increase engine speed to 2500 RPM. Vacuum should be present. If procedure fails, test duty solenoid valve and ECU terminals "2M" and "2N".
3. Install vacuum gauge between duty solenoid valve and EGR control valve. Increase engine speed to 2000 RPM and note amount of vacuum. Disconnect and plug vacuum hose at EGR control valve. Increase engine speed to 2000 RPM. Vacuum should be greater than previous reading. If procedure fails, test EGR position sensor, EGR duty solenoid valve and ECU terminal "2F".
4. With vacuum hose disconnected at EGR control valve and vacuum gauge connected, disconnect Green/Black wire of coolant temperature switch. Increase engine speed to 2500 RPM and ensure vacuum is not present. If vacuum is present, test duty solenoid valve and electronic control unit terminal "1H".

EGR CONTROL VALVE

Bring engine to normal operating temperature and run at idle. Disconnect and plug vacuum hose at EGR control valve. Engine should run smoothly. Connect vacuum pump to EGR control valve and apply more than 2.36 in. Hg. Engine should run rough or stop. If procedure fails, clean or replace EGR control valve.

Scheme 44

1. Backprobe EGR position sensor connector with voltmeter. (Scheme 44)
2. With EGR vacuum hose disconnected, connect vacuum pump. Turn ignition on and check voltages at connector. Use «EGR POSITION SENSOR VOLTAGE»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl) table to compare results. EGR POSITION SENSOR VOLTAGE Terminal Voltage A 4.5-5.5 B Less Than 1.5 C Without Vacuum.25-.95 With Vacuum Approx. 4
3. If voltage is not correct at terminals A and B, check harness and connection at ECU connector terminals No. 2A and 2C. If voltage is not correct at terminal C, check sensor resistance, harness and ECU connector terminal No. 2F.
4. Check sensor resistance according to «EGR POSITION SENSOR RESISTANCE»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl) table. If resistance is not within specifications, replace sensor.

EGR POSITION SENSOR RESISTANCE

Non-Turbo MX-6 & 626

1. Disconnect vacuum hose from solenoid. (Scheme 45) Blow through port "A". Ensure air exhausts through port "B".
2. Disconnect 2 wire connector from solenoid. Connect 12 volts to one terminal and ground other terminal of solenoid. Blow air through port "A". Ensure air exhausts through air filter.

Scheme 45

Turbo MX-6 & 626

1. Disconnect vacuum hoses and blow through vent hose. (Scheme 46) Ensure air flows. Disconnect solenoid connector.
2. Apply 12 volts to White/Blue wire ("B" connector) of solenoid and ground both Red/Black wires ("A" and "C" connectors) of solenoid. Blow through vent hose and ensure air does not flow. Replace solenoid if not okay.
3. Blow through vacuum hose and ensure air does not flow. Apply 12 volts to Blue/White wire connector of solenoid and ground both Red/Black wire connectors of solenoid. Blow through vacuum hose and ensure air does flow. Replace solenoid if not okay.

Scheme 46

Remove vacuum check valve. By blowing through vacuum check valve, ensure vacuum travels through in the direction of the arrow marked on the valve. Reverse airflow through vacuum check valve and ensure air does not flow. Replace vacuum check valve if defective.

DECELERATION CONTROL SYSTEM (MX-6, 323 & 626)

Deceleration control system is a function of ECU. It provides fuel cut during deceleration.

1. Using analog voltmeter, backprobe ECU connector terminals No. 3C or 3E. Start engine. Voltage should pulsate.
2. Increase engine speed to 4000 RPM. Suddenly decrease engine speed. Voltage should become constant during deceleration. If not, check idle switch, coolant temperature switch and all ECU connections.

HIGH ALTITUDE COMPENSATION SYSTEM (323)

High altitude compensation is a function of ECU. It provides timing advance according to altitude.

1. With engine warm, connect timing light to No. 1 cylinder. Check ignition timing. Timing at less than 3000 feet should be 7° BTDC.
2. Connect vacuum pump to atmospheric pressure sensor. Apply vacuum and check ignition timing. Timing should advance to 13° BTDC.
3. If not, inspect atmospheric pressure sensor and ECU. Ensure altitude is not greater than 3000 feet.

See also:
• BASIC TESTING - 4-CYL
• PRESSURE SWITCH VOLTAGES