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Home >> Infiniti >> 1992 >> Q45 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/O Codes >> Symptoms >> Trouble Shooting Procedures
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Trouble Shooting Procedures

  1. Ensure fuel pressure is within specification. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
  2. Test fuel injectors. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
  3. Inspect throttle body ports and valves for deposits, wear and plugging. Clean or replace as necessary.
  4. Check for spark using spark tester. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
  5. Check idle speed components. Refer to IDLE CONTROL SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
  6. Ensure battery is fully charged. Ensure battery maintains at least 9.6 volts during cranking.
  7. Check spark plug for improper gap and fouling.
  8. Ensure no vacuum leaks exist in intake system.
  9. Check fast idle system components. See IDLE CONTROL SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. On Q45, ensure fast idle cam keeps cam follower lever fully released. If cam follower lever is not kept fully released, check adjustment. See ADJUSTMENTS article in the ENGINE PERFORMANCE Section.
  10. Check EGR valve operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
  11. Check EGR solenoid valve operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
  12. Ensure engine has adequate compression. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
  13. Disconnect exhaust gas sensor, and monitor driveability. If driveability improves, replace sensor. If driveability does not improve, go to step 16).
  14. Remove canister purge line from intake, and test drive vehicle.
  15. Remove vacuum hose from fuel pressure regulator, and monitor for symptom change.
  16. Enter self-diagnostic Mode II, and monitor exhaust gas sensor operation. See FEEDBACK SYSTEM under FUEL CONTROL in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
  17. Check ECU harness connector.
  18. Substitute a known good ECU.
  19. Check ECU power supply and ground circuit. See POWER CIRCUITS and GROUND CIRCUITS under ELECTRONIC CONTROL UNIT (ECU) in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
  20. Check timing belt for proper installation.
  21. Check throttle linkage operation.
  22. Substitute a known good airflow meter.
  23. Check for intake valve deposits.
  24. Check coolant (engine) temperature sensor. See COOLANT (ENGINE) TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
  25. Check fuel level in tank.
  26. Check for oil leaks into combustion chamber.
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