LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Nissan-Datsun >> 1989 >> Sentra Base >> Repair and Diagnosis >> Engine Performance >> System >> Tests W/O Codes >> Symptom Diagnosis >> Symptom Test Procedure Definitions
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Symptom Test Procedure Definitions

The following are steps to be taken to help determine and rectify the cause of specific "symptoms".

  1. Ensure fuel pressure is within specification.
  2. Perform INJECTOR MALFUNCTION chart in the appropriate SYSTEM/COMPONENT TESTS article. See the following:
  3. Inspect throttle body ports and valves for deposits, wear or plugging. Clean or replace as necessary.
  4. Check vacuum supply to vacuum hose of fuel pressure regulator. Verify hose is not plugged. Perform FUEL PRESSURE REGULATOR SOLENOID check chart (if equipped) in the SYSTEM/COMPONENT TESTS article. See the following menu. On 300ZX check fuel surge tank for cracks, and one-way valve for clogging.
  5. Ensure ignition timing is within specification.
  6. Connect inductive timing light to spark plug wire and check for weakness of flash. To check spark, DIS will require adapter at power transistor unit, or an adapted spark plug wire between No. 1 coil and No. 1 spark plug.
  7. Ensure spark plug wires are within allowable resistance values (except DIS).
  8. Check for spark using spark tester.
  9. Monitor vehicle's tachometer while cranking engine (at least 250 RPM).
  10. Check fast idle cam operation.
  11. Check idle speed control circuit. Refer to IDLE SPEED SYSTEM in the SYSTEM/COMPONENT TESTS article. See menu below.
  12. Ensure that battery is fully charged and maintains at least 9.6 volts while cranking.
  13. Cool fuel lines with wet rags and attempt to start engine (vapor lock).
  14. Advance and retard timing while attempting to start engine.
  15. Check spark plug for improper gap or fouling.
  16. Check canister purge hoses for leaks.
  17. 17 - Dry distributor and/or ignition coil and attempt to start engine.
  18. Check blow-by hose for clogging.
  19. Ensure there are no vacuum leaks into intake system.
  20. Check fast idle system. See IDLE SPEED SYSTEM in the appropriate SYSTEM/COMPONENT TESTS article. See menu below.
  21. Check EGR control valve operation.
  22. Check EGR control valve solenoid operation.
  23. Ensure engine has adequate compression.
  24. Disconnect exhaust gas sensor and monitor change in driveability. If it improves, replace sensor. If not, go to 33.
  25. Check for proper cooling system operation. On 300ZX turbo models, ensure intake air pressure is not too high due to defective by-pass (wastegate) valve actuator.
  26. Remove canister purge line from intake and test drive vehicle.
  27. Ensure idle speed is within specification.
  28. Remove vacuum hose from fuel pressure regulator and monitor for symptom change.
  29. Check air filter for restriction.
  30. Check air injection valve. Refer to AIR INJECTION in the SYSTEM/COMPONENT TESTS article. See menu below.
  31. Remove vacuum hose from fuel pressure regulator. Apply vacuum and pressure and monitor symptom change.
  32. Check air injection valve solenoid.
  33. Enter self diagnostic mode 2 and monitor fuel metering system operation.
  34. Enter self diagnostic mode 3 and retrieve codes. If vehicle will not start, crank engine prior to entering self- diagnostic mode 3.
  35. Enter self diagnostic mode 4 and perform appropriate switch tests.
  36. Enter self diagnostic mode 5 and monitor "real time" setting of fault codes. Perform appropriate code chart in the TESTS W/CODES article. Refer to the following menu:
  37. Perform AIR REGULATOR check in the SYSTEM/COMPONENT TESTS article. See menu below.
  38. Perform POWER VALVE or SWIRL CONTROL VALVE check charts in the SYSTEM/COMPONENT TESTS article. See menu below.
scientia non olet · About LEMON Manuals