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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300, DTC P0301, DTC P0302, DTC P0303, DTC P0304, DTC P0305 Or DTC P0306 >> Diagnostic Procedures

Diagnostic Procedures

  1. If QUICK TEST was not performed, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed and any other DTCs are present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If DTC P0300 only is present, go to step  18. If DTCs P0300 and P0301-P0306 are present, go to next step.

  2. Check/Compare PID Values

    Turn all accessories off (A/C, heater, etc.). Turn Key On, Engine Off (KOEO). Access DPFEGR PID with scan tool and record values. Turn Key On, Engine Running (KOER). Compare KOEO and KOER PID values. Turn ignition off. If difference between PID values is not within 0.15 volt, go to next step. If difference between PID values is within 0.15 volt, go to step  4.
    NOTE: Perform KOER Self-Test and repair any DTCs before proceeding with this test.

  3. Check Operation Of EGR Valve

    The symptom indicates possible EGR flow at idle with no EGR DTCs output. Possible causes:
    • EGR valve not fully seating.
    • EGR vacuum regulator solenoid vent restricted.
    • Damaged EGR vacuum regulator solenoid.

    Disconnect vacuum hose at EGR valve and plug hose. Turn ignition on, engine off. Access DPFEGR PID with scan tool and record voltage. Start engine. With engine at idle, look at DPFEGR PID voltage reading and compare to engine off reading. An increase in voltage reading at idle indicates that DPFEGR sensor is sensing EGR flow. Turn ignition off. If DPFEGR PID voltage reading was more at idle by a minimum of 0.15 volt than with engine off, DPFEGR PID voltage reading indicates EGR flow at idle. Since vacuum hose to EGR is disconnected and plugged, fault is most likely in EGR valve. Remove and inspect EGR valve for signs of contamination, unusual wear, carbon deposits binding or other damage. Repair as necessary. After repair, go to step  20. If DPFEGR PID voltage reading was not as specified, a fault in EGR vacuum supply is indicated. Inspect EGR Vacuum Regulator (EGRVR) solenoid vent and vent filter for restrictions. Repair as necessary. If no restrictions are found, replace EGRVR solenoid. After repair, go to step  20.

    WARNING: Fuel system will remain pressurized when engine is not running. To prevent injury or fire, use caution when working on fuel system.

  4. Check Fuel Pressure

    Install fuel pressure gauge. Start engine. Note fuel pressure. Increase engine speed to 2500 RPM and maintain for 1 minute. Note and compare fuel pressure. Turn ignition off. If fuel pressure was 55-70 psi (380-482 kPa) and it remained at specification within 5 psi (35 kPa) for 60 seconds, go to next step. If fuel pressure was not as specified, refer to FUEL DELIVERY SYSTEM  testing.

  5. Check Injector Driver PIDS INJ1F Through INJ6F

    Turn ignition on, engine off. Access appropriate PID(s) for suspect fuel injector. If PID status is YES, go to next step. If PID status is NO, go to step  9.

  6. Check Resistance Of Fuel Injector(s) & Harness

    Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Measure resistance of INJ circuit between breakout box terminal No. 71 or 97 and suspect fuel injector breakout box terminal. See BREAKOUT BOX INJECTOR TERMINAL IDENTIFICATION  table. If resistance reading is 11-18 ohms, replace PCM. After repair, go to step  9. If resistance reading is not as specified, go to next step.
    BREAKOUT BOX INJECTOR TERMINAL IDENTIFICATION

    Injector Circuit Breakout Box Terminal No. (2.0L) Breakout Box Terminal No. (3.0L)
    INJ1F 70 75
    INJ2F 96 101
    INJ3F 20 74
    INJ4F 95 100
    INJ5F N/A 73
    INJ6F N/A 99

  7. Check Resistance Of Fuel Injector Harness

    Disconnect harness connector at suspected fuel injector. Measure resistance of VPWR circuit between breakout box terminal No. 71 or 97 and fuel injector harness connector. Measure resistance of INJ circuit between appropriate breakout box terminal and fuel injector harness connector. See BREAKOUT BOX INJECTOR TERMINAL IDENTIFICATION  table. If each resistance reading is less than 5 ohms, go to next step. If each resistance reading is not as specified, go to step  9.

  8. Check Fuel Injector Harness Circuit For Short To Power Or Ground

    Measure resistance between breakout box terminal No. 71 (VPWR) and suspect fuel injector SIG circuit terminal(s). Measure resistance between breakout box terminal No. 103 (PWR GND) and suspect fuel injector SIG circuit breakout box terminal(s). See BREAKOUT BOX INJECTOR TERMINAL IDENTIFICATION  table. If each resistance reading is more than 10,000 ohms, go to next step. If each resistance reading is not as specified, repair short circuit. See WIRING DIAGRAMS article. After repair, go to step  20.

  9. Inspect Fuel Injector Operation

    Remove fuel injector from suspect cylinder. Swap suspect fuel injector with a fuel injector from another cylinder. Start engine. If misfire DTC does not move to cylinder with suspect fuel injector, go to next step. If misfire DTC moves to cylinder with suspect injector, replace fuel injector. After repair, go to step  20.

  10. Check Vacuum System

    Inspect all vacuum lines for damage, such as pinched lines, cracks, proper routing and assembly. If vehicle vacuum system is okay, go to next step. If vacuum system is not okay, repair as necessary. After repair, go to step  20.
    CAUTION: Remove front under cover if necessary to observe crankshaft pulley.

  11. Check Damper & Pulley Assembly

    Observe crankshaft pulley for wobble. Examine pulse ring fastened to harmonic damper. If no problem is found, go to next step. If crankshaft pulley wobbles or pulse ring is loose or damaged, replace damper or pulse ring. Disconnect battery for 5 minutes to allow PCM to learn new data. After repair, go to step  20.
    NOTE: Misfire Monitor can be influenced by Evaporative Emission (EVAP) system. Next five test steps will diagnose EVAP system.

  12. Check EVAP System

    Check EVAP canister for fuel saturation. If there is an excess amount of liquid fuel present in EVAP canister, replace EVAP canister. After repair, go to step  20. If an excess amount of liquid fuel is not present, check fuel tank vent system. Go to next step.

  13. Pressure Test Evaporative Emission System

    Perform EVAPORATIVE EMISSIONS SYSTEM LEAK TEST under SYSTEM TESTS (EVAPORATIVE EMISSION) in SYSTEM & COMPONENT TESTING - B2300, B3000, B4000 & TRIBUTE article. If EVAP system is holding pressure, go to next step. If EVAP system is leaking, repair as necessary. After repair, go to next step.

  14. Check Vacuum In EVAP System

    Check for blockage/restrictions or cut hoses between engine vacuum port and EVAP canister. Check for blockage in fuel tank vent system. If no fault is indicated, go to next step. If fault is indicated, replace damaged vacuum hoses or remove blockage/restrictions. After repair, go to step  20.

  15. Check For EVAP Canister Purge Valve Housing Leaks

    Verify EVAP canister purge valve harness connector is connected. Install hand vacuum pump to fuel vapor port on EVAP canister purge valve. Apply 16 in. Hg (53 kPa) of vacuum with vacuum pump. If EVAP canister purge solenoid holds vacuum at room temperature, go to next step. If EVAP canister purge solenoid does not hold vacuum, replace EVAP canister purge solenoid. After repair, go to step  20.

  16. Check For Filter Contamination Or Damage On EVAP Canister Purge Valve

    Remove vacuum line from input port to intake manifold on EVAP canister purge solenoid (control vacuum solenoid part of valve). Install a hand held vacuum pump to open input vacuum port on EVAP canister purge solenoid. Apply 10-15 in. Hg (48-52 kPa) of vacuum to EVAP canister purge solenoid. If EVAP canister purge solenoid valve does not hold vacuum, remove vacuum pump and go to next step. If EVAP canister purge valve holds vacuum or if valve is very slow to release vacuum to atmosphere, service EVAP canister purge solenoid filter. If unable to clean filter or remove blockage, replace EVAP canister purge solenoid. After repair, go to step  20.
    NOTE: This step will determine if there are any base engine concerns that may have caused misfire DTC or driveability concern.

  17. Check For Base Engine Concerns

    Perform the following tests in order to evaluate base engine integrity.
    • Perform Engine Compression Test.
    • Perform Valve Train Analysis.
    • Check PCV system.
    • Check possible leakage points.

    If any service is required, service as necessary. After service, go to step  20.

  18. Check/Compare PID Values

    Turn all accessories off (A/C, heater, etc.). Turn Key On, Engine Off (KOEO). Access DPFEGR PID with scan tool and record values. Turn Key On, Engine Running (KOER). Compare KOEO and KOER PID values. Turn ignition off. If difference between PID values is within 0.15 volt, disconnect scan tool and go to next step. If difference between PID values is not within 0.15 volt, go to step  20.

  19. Check CMP Sensor Output

    Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) between PCM harness connector and PCM. See Figure. Set multimeter on AC scale (monitor less than 5.0 volts). Measure voltage between breakout box terminal No. 85 (CMP) and terminals No. 51 and 103 (PWR GND) while running engine at varying RPM. If AC voltage varies more than 0.1 volt, ensure Camshaft Position (CMP) sensor is installed correctly. If CMP sensor is installed correctly, replace PCM. After repair, go to next step. If AC voltage reading does not vary as specified, replace CMP sensor. After repair, go to next step.

  20. Drive Cycle

    Reconnect all disconnected connectors. Clear DTCs from PCM memory using scan tool generic OBD-II function. Perform FUEL OR MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE  under MONITOR REPAIR VERIFICATION DRIVE CYCLES. Retrieve pending code. If same DTC is present replace PCM. After repair, go to next step. If same DTC is not present, go to next step.

  21. Verify Trouble Shooting Of DTCs Completed

    Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any DTC is present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are set, trouble shooting is complete.
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