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Tests W/o Codes Mazda 323 BF

Testing & Diagnostics ~1425 words

SYMPTOM DIAGNOSIS

Use this section to diagnose driveability problems that exist when a hard fault code is not present. Symptom checks are intended to direct the technician to malfunctioning component(s) so that further diagnosis may be performed. A "symptom" should lead to further testing of specific components or systems, or verification of adjustment specifications.

Note. For specific component test procedures, refer to

  1. 4-Cyl. MPFI, See: «SYSTEM/COMPONENT TESTS - 4-CYL»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#systemcomponent-tests-4-cyl)
  2. Rotary RX7, See: «SYSTEM/COMPONENT TESTS»(ref-18100)

For specifications, go to

  1. 4-Cylinder, See: «SPECIFICATIONS - 4-CYL»(ref-18086)
  2. Rotary RX7, See: «SPECIFICATIONS»(ref-18088)

For adjustment procedures, go to

  1. 4-Cylinder, See: «ADJUSTMENTS - 4-CYL»(ref-18089)
  2. Rotary RX7, See: «ADJUSTMENTS»(ref-18091)

Symptom checks cannot be used properly unless the problem is actually happening while the car is being tested. To reduce diagnostic time, ensure steps in the following articles have been performed before attempting to diagnose a symptom. See the following menu

BASIC DIAGNOSTICS

  1. 4-Cylinder Cars & Trucks, see: «BASIC TESTING - 4-CYL»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl)
  2. Rotary, see: «BASIC TESTING»(ref-18097)

CODE TESTING

  1. 4-Cylinder MPFI Cars, see: «TESTS W/CODES - MPFI»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#tests-wcodes-mpfi)
  2. 4-Cylinder Turbo Cars, see: «TESTS W/CODES - TURBO»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#tests-wcodes-turbo)
  3. Rotary models, see: «TESTS W/CODES»(ref-18103)

For symptoms available for diagnosis and a link to the associated headings, see the SYMPTOM-TO-DIAGNOSIS MENU below.

SYMPTOM-TO-DIAGNOSIS MENU

SymptomGo To
Difficult or no start (cranks okay)DIFFICULT/NO START
Rough or unstable idleROUGH/UNSTABLE IDLE
Excessive fast idleEXCESSIVE FAST IDLE
Engine stallsENGINE STALLS
Engine misfires or has lack of powerMISFIRES/LACK OF POWER
Engine runs rough on decelerationRUNS ROUGH/DECELERATION
Afterburn in exhaust systemEXHAUST SYSTEM AFTERBURN
Poor fuel mileagePOOR FUEL MILEAGE
Excessive oil consumptionEXCESSIVE OIL CONSUMPTION
Abnormal noise or knockingNOISE OR KNOCKING

SYMPTOM-TO-DIAGNOSIS MENU

DIFFICULT/NO START

  1. Check battery condition.
  2. Check Electronic Gasoline Injection (EGI) main fuse located in fuse box (if equipped).
  3. Verify crank angle sensor at connector has correct resistance values (929, RX-7 and most turbocharged models).
  4. Check main relay operation. A click should heard from main relay as ignition switch is cycled on and off.
  5. Verify distributor connector parallel terminal resistance is correct.
  6. Ensure distributor pick-up coil resistance is correct.
  7. Ensure pressure regulator control system is okay.
  8. Ensure Secondary Air Injection system is functioning correctly (if equipped).
  9. Check air intake system for restriction.
  10. Check EGR valve and solenoid for correct operation.
  11. Check for cracks or poor connections at airflow meter or throttle body.
  12. Ensure ignition coil has correct resistance.

ROUGH/UNSTABLE IDLE

  1. Use sound amplification tool to verify operational noise coming from fuel injector(s).
  2. Ensure fuel system pressure is correct.
  3. Check PCV system for restrictions.
  4. Check coolant thermosensor for correct resistance.
  5. Check air valve or ISC valve for malfunction.
  6. Check connections at airflow meter or throttle body.
  7. Check for cracks or poor connections at airflow meter or throttle body.
  8. Check O2 sensor for 0-1.0 volt output while changing engine RPM up and down.
  9. Verify throttle position sensor has correct adjustment and resistance value.
  10. Check for purge valve malfunction.
  11. Check for poor connections at airflow meter or throttle body.

EXCESSIVE FAST IDLE

  1. Verify correct throttle body dashpot adjustment.
  2. Check By-Pass Air Control (BAC) valve and ISC valve operation.
  3. Check air intake system for leaks or restriction.
  4. Check pressure regulator control system.
  5. Ensure fuel system pressure is correct.
  6. Check water thermosensor.
  7. Check airflow meter for cracks. Verify correct airflow operation and resistance value.

FUEL INJECTED MODELS (COLD)

  1. Ensure air intake system is unrestricted.
  2. Remove By-Pass Air Control (BAC) valve hose and check valve for restrictions. If no restrictions are found, check resistance at BAC valve terminals.
  3. Check EGR valve and solenoid for correct operation.
  4. Check intake air and water thermosensor.
  5. Check airflow meter or ISC valve malfunction.
  6. Check A/C cut-off system.
  7. Ensure fuel system pressure is correct.
  8. Check for cracks or poor connections at airflow meter or throttle body.
  9. Verify correct throttle position sensor adjustment and resistance value.

FUEL INJECTED MODELS (WARM)

  1. Check PCV system for restrictions.
  2. Check air valve or ISC valve malfunction.
  3. Check connections at airflow meter or throttle body.
  4. Ensure fuel system pressure is correct. Use ohmmeter to verify correct fuel injector resistance.
  5. Check throttle bore for dirt or carbon.

MISFIRES/LACK OF POWER

  1. Verify air intake system is unrestricted.
  2. Check EGR valve and solenoid for correct operation.
  3. Check No. 1 and No. 2 purge control valve operation.
  4. Check vacuum switching valve operation.
  5. Check airflow meter for cracks.
  6. Check airflow operation and resistance value.
  7. Check atmospheric pressure sensor.
  8. Check secondary air injection system (RX-7).
  9. Check Variable Dynamic Effect Intake (VDI) system (RX-7).
  10. Check variable resonance induction system for correct operation (except RX-7).
  11. Verify connector at crank angle sensor has correct resistance values (929, RX-7 and most turbocharged models).
  12. Check A/C cut-off system.
  13. Check triple induction control system for correct operation (if equipped).
  14. Ensure fuel system pressure is correct. Use ohmmeter to verify fuel injector terminal resistance.

Check turbo system for damage or wear (if equipped). Turbo system inspection should include the following components

  1. Air By-Pass valve
  2. Engine control unit (ECU).
  3. Intake air thermosensor in airflow meter.
  4. Knock sensor and knock control unit.
  5. Turbo wastegate solenoid valve.

RUNS ROUGH/DECELERATION

  1. Verify correct throttle body dashpot adjustment.
  2. Check water thermosensor and throttle position sensor.
  3. Check triple induction control system for correct operation (if equipped).
  4. Check air valve or ISC valve for malfunction.
  5. Ensure fuel system pressure is correct.

EXHAUST SYSTEM AFTERBURN

  1. Verify base timing and timing advance system is functional.
  2. Check throttle body dashpot adjustment.
  3. Check secondary air injection system (RX-7).
  4. Check water thermosensor and throttle position sensor.
  5. Check air valve, ISC switch and idle switch operation.
  6. Check intake air system and throttle body electrical connections.
  7. Ensure fuel system pressure is correct.
  8. Verify no leaks in exhaust system.

POOR FUEL MILEAGE

  1. Verify correct throttle body dashpot adjustment.
  2. Ensure correct throttle position sensor adjustment and resistance value.
  3. Check intake air and water thermosensor.
  4. Ensure fuel system pressure is correct.
  5. Ensure exhaust system is unrestricted.

EXCESSIVE OIL CONSUMPTION

  1. Check for restricted PCV system.
  2. Check turbo system for malfunction.

NOISE OR KNOCKING

Check engine oil level. Check Electronic Spark Advance (ESA) control system for malfunctioning component. ESA system inspection should include the following components

  1. Airflow meter.
  2. Idle switch.
  3. Neutral safety switch (A/T).
  4. Clutch switch (M/T).
  5. EGR position sensor.
  6. Knock sensor.
  7. Throttle position sensor.
  8. Water thermosensor.
  9. Water thermo switch.
  10. Inhibitor switch (A/T).
  11. Electronic Controlled Automatic Transmission (ECAT) unit.

Check turbo system for damage or wear (if equipped). Turbo system inspection should include the following components

  1. Air By-Pass valve.
  2. Engine control unit (ECU).
  3. Intake air thermosensor in airflow meter.
  4. Knock senor and knock control unit.
  5. Turbo wastegate solenoid valve.

FAILS EMISSION TEST

  1. Ensure exhaust system is not restricted.
  2. Check EGR valve and solenoid for correct operation.
  3. Check fuel-cut system for malfunction. Fuel-cut system includes throttle body dashpot unit, throttle position sensor and water thermosensor.
  4. Check No. 1 and No. 2 purge control valve operation.
  5. Check vacuum switching valve operation.
  6. Check secondary air injection system (RX-7).
  7. Check airflow meter for cracks.
  8. Verify correct airflow meter operation and resistance value.
  9. Check atmospheric pressure sensor.
  10. Check air valve and ISC switch.
  11. Ensure fuel system pressure is correct.
  12. Verify intake air system and throttle body electrical connections.
  13. Check pressure regulator and pressure regulator solenoid.
  14. Verify water and intake air thermosensor.
  15. Verify throttle position sensor adjustment.

INTERMITTENT PROBLEM DIAGNOSIS

Intermittent problems may cause a noticeable driveability problem or cause the Malfunction Indicator Light (MIL) to illuminate. Before attempting to diagnose an intermittent fault, make sure the basic testing procedures in the BASIC TESTING article and the code testing steps in the TESTS W/CODES article (if applicable) have been performed. See the following menu

  1. 4-Cylinder Cars & Trucks, see: «BASIC TESTING - 4-CYL»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl)
  2. Rotary RX7, see: «BASIC TESTING»(ref-18097)
  1. 4-Cylinder MPFI Cars, see: «TESTS W/CODES - MPFI»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#tests-wcodes-mpfi)
  2. 4-Cylinder Turbo Cars, see: «TESTS W/CODES - TURBO»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#tests-wcodes-turbo)
  3. Rotary RX7, see: «TESTS W/CODES»(ref-18103)

Intermittent fault testing requires duplication of circuit or component failure in order to identify the fault. These procedures may cause the computer to record a fault code which may help in diagnosis.

If the vehicle's problem does not produce fault codes, it will be necessary to monitor voltage or resistance values using a DVOM while attempting to produce conditions which will create an intermittent fault. A change in status on the DVOM will indicate a fault has been located.

TEST PROCEDURES

To produce the conditions which will create an intermittent fault so that it may be identified during testing, some of the following methods may be used

  1. Applying light vibration to components.
  2. Apply heat to component.
  3. Wiggling or bending a wiring harness.
  4. Applying humidity to a component.
  5. Remove or apply a vacuum supply source.
  6. Disconnect or adjust a component.

Use the results of these tests to identify a faulty component or an area which should be checked closely for the problem.

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