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Home >> Infiniti >> 2003 >> M45 >> Repair and Diagnosis >> Engine Performance >> Engine Controls - On-Vehicle Adjustments >> Throttle Position Sensor, Ignition Timing & Idle Speed >> Basic Inspection >> QX4

Basic Inspection: QX4

  1. Check service records for any recent repairs that may indicate a related problem, or a current need for a scheduled maintenance. Check for the following:
    • Air cleaner clogging.
    • Hoses and ducts for leaks.
    • Electrical connectors.
    • Gasket.
    • Throttle valve and throttle position sensor operation.
    Start engine and warm until coolant temperature gauge is pointing to middle of gauge. Ensure engine speed is less than 1000 RPM. Hold engine speed at 2000 RPM for about 2 minutes. Using scan tool, ensure no DTCs are set. If results are okay, go to step  3. If results are not okay, go to next step.
  2. Repair or replace components as necessary. If repair or replacement results are okay, go to next step.
  3. Check Target Idle Speed with engine warmed up to normal operating temperature. Idle speed should be 700-800 RPM with transmission in Park or Neutral position. If idle speed is okay, go to step  12. If idle speed is not okay, go to next step.
  4. Perform the Idle Air Volume Learning procedure. See appropriate SELF DIAGNOSTICS article. If procedure okay, go to next step. If procedure is not okay, repair as necessary, then go to next step.
  5. Check Target Idle Speed again with engine warmed up to normal operating temperature. Idle speed should be 700-800 RPM with transmission in Park or Neutral. If idle speed is okay, go to step  10. If idle speed is not okay, go to next step.
  6. Replace Idle Air Control Valve-Auxiliary Air Control (IACV-AAC) valve. Go to next step.
  7. Perform Idle Air Volume Learning procedure. See appropriate SELF DIAGNOSTICS article. If procedure okay, go to next step. If result is not okay, go to step  4.
  8. Check Target Idle Speed again with engine warmed up to normal operating temperature. Idle speed should be 700-800 RPM with transmission in Park or Neutral. If idle speed is okay, go to step  10. If idle speed is not okay, go to next step.
  9. Substitute known-good ECM to check ECM functionality. Go to step  4.
  10. Start engine to check ignition timing with engine warmed up to normal operating temperature. Check ignition timing at idle using timing light. Ignition timing should be 10-20 BTDC in Park or Neutral position. See. If results okay, go to step  12. If results not okay, go to next step.
  11. Check timing chain installation. See appropriate ENGINE article. If results are okay, go to step  9. If results are not okay, repair as necessary, then go to step  4.
  12. Start engine to check ignition timing at idle using timing light. Ignition timing should be 10-20 BTDC in Park or Neutral position. If results are okay, go to step  18. If results are not okay, go to next step.
  13. Perform the Idle Air Volume Learning procedure. See appropriate SELF DIAGNOSTICS article. If procedure is okay, go to next step. If procedure is not okay, repair as necessary, then go to next step.
  14. Check Target Idle Speed again with engine warmed up to normal operating temperature. Idle speed should be 700-800 RPM with transmission in Park or Neutral. If idle speed is okay, go to step  16. If idle speed is not okay, go to next step.
  15. Substitute another known-good ECM to check ECM functionality. Go to step  13.
  16. Start engine to check ignition timing at idle using timing light. Ignition timing should be 10-20 BTDC in Park or Neutral position. If results okay, go to step  18. If results not okay, go to next step.
  17. Check timing chain installation. See appropriate ENGINE article. If results are okay, go to step  15. If results are not okay, repair as necessary, then go to step  13.
  18. Erase unnecessary DTCs that may be displayed. Erase stored memory in ECM and TCM. Go to next step.
  19. Check Heated Oxygen Sensor 1 (Bank 2) signal. Run engine about 2000 RPM for about 2 minutes under no-load. Follow procedures accordingly:
    • With CONSULT II -  See HO2S1 MNTR (B2) in DATA MONITOR mode. With engine running at 2000 RPM under no-load at normal operating temperature, check that the monitor fluctuates between LEAN and RICH more than 5 times during 10 seconds. If results are okay, go to step  22. If results are not okay, and monitor does not fluctuate, go to step  26, or if monitor fluctuates less than 5 times, go to next step.
    • Without CONSULT II -  Set voltmeter probe between ECM terminal 62 and ground. Make sure that the voltage fluctuates between 0-0.3 volts and 0.6-1.0 volts more than 5 times during 10 seconds at 2000 RPM. If results are okay, go to step  22. If results are not okay, and monitor does not fluctuate, go to step  26, or if monitor fluctuates less than 5 times, go to next step.
  20. Stop engine, check Heated Oxygen Sensor 1 (Bank 2). Replace heated oxygen sensor 1 (Bank 2), then start engine to normal operating temperature at 2000 RPM for 2 minutes under no-load. Follow procedures accordingly:
    • With CONSULT II -  See HO2S1 MNTR (B2) in DATA MONITOR mode. Run engine at 2000 RPM under no-load at normal operating temperature to check if the monitor fluctuates between LEAN and RICH more than 5 times during 10 seconds. If results are okay, go to step  22. If results are not okay, go to step  21.
    • Without CONSULT II -  Set voltmeter probe between ECM terminal 62 and ground. Make sure that the voltage fluctuates between 0-0.3 volts and 0.6-1.0 volts more than 5 times during 10 seconds at 2000 RPM. If results are okay, go to step  22. If results are not okay, go to step  21.
  21. Detect malfunctioning part by checking the following:
    • Fuel pressure regulator.
    • Mass air flow sensor and its circuit.
    • Injector and its circuit. Clean or replace if necessary.
    • Engine coolant temperature sensor and it's circuit.
    • ECM function by substituting another known-good ECM.
    If results are okay, go to step  3.
  22. Check Heated Oxygen Sensor 1 (Bank 1) signal. Follow procedures accordingly:
    • With CONSULT II -  See HO2S1 (B1) in DATA MONITOR mode. Run engine at 2000 RPM under no-load at normal operating temperature. Check that the monitor fluctuates between LEAN and RICH more than 5 times during 10 seconds. If results are okay, then inspection is ended. If results are not okay, and monitor does not fluctuate, go to step  25, Or if monitor fluctuates less than 5 times, go to next step.
    • Without CONSULT II -  Set voltmeter probe between ECM terminal 63 and ground. Make sure that the voltage fluctuates between 0-0.3 volts and 0.6 - 1.0 volts more than 5 times during 10 seconds at 2000 RPM. If results are okay, then inspection is ended. If results are not okay, and monitor does not fluctuate, go to step  25, or if monitor fluctuates less than 5 times, go to next step.
  23. Stop engine, replace Heated Oxygen Sensor 1 (Bank 1). Start engine, run at 2000 RPM for 2 minutes under no-load at normal operating temperature. Follow procedures accordingly:
    • With CONSULT II -  See HO2S1 (B1) in DATA MONITOR mode. Run engine at 2000 RPM under no-load at normal operating temperature. Check that the monitor fluctuates between LEAN and RICH more than 5 times during 10 seconds. If results are okay, then inspection is ended. If results are not okay, go to next step.
    • Without CONSULT II -  Set voltmeter probe between ECM terminal 63 and ground. Make sure that the voltage fluctuates between 0-0.3 volts and 0.6-1.0 volts more than 5 times during 10 seconds at 2000 RPM. If results are okay, then inspection is ended. If results are not okay, go to next step.
  24. Detect malfunctioning part by checking the following:
    • Fuel pressure regulator.
    • Mass air flow sensor and its circuit.
    • Injector and its circuit. Clean or replace if necessary.
    • Engine coolant temperature sensor and it's circuit.
    • ECM function by substituting another known-good ECM.
    If results are okay, go to step  3.
  25. Check Heated Oxygen Sensor 1 (Bank 1) harness. Turn engine off and disconnect battery ground cable. Disconnect ECM harness connector, Heated Oxygen Sensor 1 (Bank 1) harness connector. Check harness continuity between ECM terminal 63 and Heated Oxygen Sensor 1 (Bank 1) harness connector terminal 2. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Continuity should exist. If procedure okay, go to step  28. If procedure not okay, go to step  27.
  26. Check Heated Oxygen Sensor 1 (Bank 1) harness. Turn engine off and disconnect battery ground cable. Disconnect ECM harness connector, Heated Oxygen Sensor 1 (Bank 1) harness connector. Check harness continuity between ECM terminal 62 and Heated Oxygen Sensor 1 (Bank 1) harness connector terminal 2. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Continuity should exist. If procedure okay, go to step  28. If procedure not okay, go to next step.
  27. Repair or replace harness between ECM and Heated Oxygen Sensor 1 then go to step  3.
  28. Preparation for CO% check. Follow procedures accordingly:
    • With CONSULT II -  Reconnect ECM harness connector. Turn ignition switch ON. Select ENG COOLANT TEMP in ACTIVE TEST mode. Set ENG COOLANT TEMP to 41°F (5°C) by touching DOWN and Qd. If results as specified, go to next step.
    • Without CONSULT II -  Disconnect ECM harness connector and engine coolant temperature sensor harness connector. Connect a resistor (4.4 kΩ) between terminals of engine coolant temperature sensor harness connector. If results as specified, go to next step.
  29. Checking CO%, start engine and warm up until engine coolant temperature indicator points to the middle of gauge. Rev engine at 2000-3000 RPM 2 or 3 times under no-load, then run engine at idle speed. Check CO%. Follow procedures accordingly:
    • With CONSULT II -  Results will idle CO: 1.0-9.5%. If results are okay, go to next step. If results are not okay, go to step  31.
    • Without CONSULT II -  After checking CO%, disconnect resistor from terminals of engine coolant temperature sensor. Connect engine coolant temperature sensor harness connector to engine coolant temperature sensor. If results are okay, go to next step. If results are not okay, go to step  31.
  30. Check Heated Oxygen Sensor 1 (Bank 1)/(Bank 2) signal. Stop engine and replace Heated Oxygen Sensor 1 (Bank 1)/(Bank 2). Start engine and warm up to normal operating temperature. Run engine at 2000 RPM for 2 minutes with no-load. Follow procedures accordingly:
    • With CONSULT II -  See HO2S1 MNTR (B1)/(B2) in DATA MONITOR mode. Keep engine at 2000 RPM with no-load at normal operating temperature. Check that the monitor fluctuates between LEAN and RICH more than 5 times during 10 seconds. If results are okay, go to step  3. If results are not okay, go to next step.
    • Without CONSULT II -  Set voltmeter probe between ECM terminal 63 or 62 and ground. Make sure that voltage fluctuates between 0-0.3 volts and 0.6-1.0 volts more than 5 times during 10 seconds at 2000 RPM. If results are okay, go to step  3. If results are not okay, go to next step.
  31. Detect malfunctioning parts by checking the following:
    • Connect heated oxygen sensor 1 harness connectors to heated oxygen sensors 1.
    • Fuel pressure regulator.
    • Mass air flow sensor and its circuit.
    • Injector and its circuit. Clean or replace if necessary.
    • Engine coolant temperature sensor and its circuit.
    • ECM function by substituting another known good ECM.
    If results are okay, go to step  3.
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