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Home › Infiniti › 2001 › QX4 4WD › Repair and Diagnosis › Engine Performance › Engine Controls - On-Vehicle Adjustments › Throttle Position Switch, Ignition Timing & Idle Speed › Basic Inspection › Sentra 2.0L

Sentra 2.0L

NOTE: Use the following procedure to check and adjust throttle position switch, ignition timing and idle speed. Ensure no Diagnostic Trouble Codes (DTCs) exist before performing test. See SELF-DIAGNOSTICS - SENTRA 2.0L article. Ensure transmission is in Park or Neutral, all electrical accessories (headlights, A/C, rear window defogger, cooling fan, etc.) are turned off and steering wheel is in straight-ahead position.
  1. Check the following:
    • Harness connectors for improper connections.
    • Wiring for improper connections, pinches and cuts.
    • Air cleaner for clogging.
    • Hoses and ducts for leaks.

    Repair as necessary. Go to next step.

  2. Check Throttle Opener Operation

    While starting engine, inspect throttle opener rod. Throttle opener rod should retract more than.118" (3.00 mm), and throttle drum should not be contacting throttle opener rod. See Fig 1. If operation is as specified, go to step  5. If operation is not as specified, go to next step.

  3. Check Throttle Opener Vacuum Source

    Turn ignition off. Disconnect vacuum hose from throttle opener. Connect a vacuum gauge to disconnected hose. Start engine and let it idle. If vacuum is more than 11.81 in. Hg, go to next step. If vacuum is 11.81 in. Hg or less, repair blockage or leak in vacuum hose or blockage in vacuum port as necessary.

  4. Check Throttle Opener

    Using a hand vacuum pump, apply at least 11.81 in. Hg of vacuum to throttle opener. Throttle opener rod should move more than.118" (3.00 mm) and should not be contacting throttle drum. If operation is as specified, reconnect vacuum hose, and go to step  2. If operation is not as specified, replace throttle opener.

  5. Check Throttle Drum Operation

    With engine idling, inspect throttle drum. Throttle drum should be contacting throttle stop. See Fig 2. If operation is as specified, go to step  7. If operation is not as specified, go to next step.

  6. Check Throttle Operation

    Turn ignition off. Ensure throttle cable is adjusted properly. Remove air intake duct. While moving throttle drum by hand, inspect throttle valve operation. If throttle valve operation is okay, retighten throttle drum mounting nuts. If throttle valve operation is not okay, clean throttle body and throttle valve.

  7. Check TP Switch Idle Position

    Start engine and warm to normal operating temperature. Turn ignition off. Disconnect vacuum hose from throttle opener. Using a hand vacuum pump, apply vacuum to throttle opener until throttle opener rod is not contacting throttle drum. Disconnect TP switch harness connector. See Fig 3. Go to next step.
  8. Insert a.002" (.05 mm) feeler gauge between throttle drum and throttle stop as shown in illustration. See Fig 4. Check continuity between TP switch terminals No. 5 and 6. See Figure. Continuity should exist. Remove.002" (.05 mm) feeler gauge, and insert.006" (.15 mm) feeler gauge. Continuity should not exist. If continuity is as specified, go to step  11. If continuity is not as specified, go to next step.

  9. Adjust TP Switch Idle Position

    Loosen TP sensor mounting bolts. Remove.006" (.15 mm) feeler gauge, and insert.002" (.05 mm) feeler gauge. Ensure throttle opener rod is still not contacting throttle drum. Apply vacuum to throttle opener as necessary. Rotate TP sensor counterclockwise until continuity does not exist. Slowly rotate TP sensor clockwise until continuity exists, then tighten TP sensor mounting bolts. Go to next step.
  10. Open and close throttle 2 or 3 times to ensure continuity exists when throttle is closed and does not exist when throttle is open. Remove.002" (.05 mm) feeler gauge, and insert.006" (.15 mm) feeler gauge. Open and close throttle 2 or 3 times to ensure continuity does not exist when throttle is closed. Go to next step.

  11. Reset TP Sensor Idle Position Memory

    Remove feeler gauge. Ensure throttle opener rod is still not contacting throttle drum. Apply vacuum to throttle opener as necessary. Plug vacuum hose that was connected to throttle opener. Reconnect TP switch harness connector. Start engine and warm to normal operating temperature. Turn ignition off. Turn ignition on, wait at least 5 seconds, then turn ignition off and wait at least 10 seconds. Repeat 20 times. Go to next step.

  12. Check Ignition Timing

    Turn ignition off. Reconnect throttle opener vacuum hose. Start engine and warm, to normal operating temperature. Turn ignition off. Disconnect TP sensor harness connector. See Fig 3. Start engine and let it idle. Check ignition timing using a timing light. Ignition timing should be 13-17 degrees BTDC with transmission in Park or Neutral. If ignition timing is as specified, go to next step. If ignition timing is not as specified, adjust ignition timing by turning distributor.
  13. Turn ignition off. Reconnect TP sensor harness connector. Start engine and let it idle. Check ignition timing using a timing light. Ignition timing should be 13-17 degrees BTDC with transmission in Park or Neutral. If ignition timing is as specified, go to step  19. If ignition timing is not as specified, go to next step.

  14. Perform Idle Air Volume Learning

    Perform idle air volume learning. See REMOVAL, OVERHAUL & INSTALLATION article. Go to next step.

  15. Check Ignition Timing Again

    Check ignition timing at idle using a timing light. Ignition timing should be 13-17 degrees BTDC with transmission in Park or Neutral. If ignition timing is as specified, go to step  19. If ignition timing is not as specified, go to next step.

  16. Check For Intake Air Leak

    With engine idling, listen for a vacuum leak. Pay particular attention to PCV hose and Idle Air Control Valve-Auxiliary Air Control (IACV-AAC) valve. If a leak is found, repair as necessary, then go to step  14. If no leak is found, go to next step.

  17. Check IACV-AAC Valve

    Check IACV-AAC valve and circuit function. See DTC P0505: IDLE AIR CONTROL VALVE-AUXILIARY AIR CONTROL (IACV-AAC) VALVE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - SENTRA 2.0L article. If a problem is found, repair as necessary, then go to step  14. If no problem is found, go to next step.

  18. Check ECM Function

    Substitute a known good ECM to check ECM function. Perform initialization of Nissan Vehicle Immobilizer System (NVIS) system and registration of NVIS ignition key IDs. See appropriate IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. Go to step  14.

  19. Check Target Idle Speed

    Ensure engine is at normal operating temperature. Check idle speed. Target idle speed should be 750-850 RPM with transmission in Park or Neutral. If idle speed is as specified, go to step  22. If idle speed is not as specified, go to next step.

  20. Perform Idle Air Volume Learning

    Perform idle air volume learning. See REMOVAL, OVERHAUL & INSTALLATION article. Go to next step.

  21. Check Target Idle Speed Again

    Ensure engine is at normal operating temperature. Check idle speed. Target idle speed should be 750-850 RPM with transmission in Park or Neutral. If idle speed is as specified, go to NEXT step. If idle speed is not as specified, go to step  16.

  22. Clear DTC Memory

    DTCs may be stored in ECM and/or Transmission Control Module (TCM) from performing basic inspection. Clear DTCs from ECM and TCM. See SELF-DIAGNOSTICS - SENTRA 1.8L article.
Fig 1: Identifying Throttle Opener Rod (Sentra 2.0L)
G00051927Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Identifying Throttle Drum & Throttle Stop (Sentra 2.0L)
G00051926Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 3: Locating TP Sensor & TP Switch Harness Connectors (Sentra 2.0L)
G00015021Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 4: Checking TP Switch Idle Position (Sentra 2.0L)
G00051928Courtesy of NISSAN MOTOR CO., U.S.A.
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