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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 34 (Engine Controls - On-Vehicle Adjustments - 4 CYL & V6) >> Throttle Position Switch, Ignition Timing & Idle Speed >> Basic Inspection >> Quest

Basic Inspection: Quest

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2002 Nissan Xterra, 2002 Nissan Sentra, 2002 Nissan Quest, 2002 Nissan Pathfinder, and 2002 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.
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 - QUEST 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 poor connections.
    • Vacuum hoses for leaks, kinks or misrouting.
    • Wiring for improper connections, pinches and cuts.

    Repair as necessary. Go to next step.

  2. Check Fast Idle Cam Function

    Using scan tool, select MODE 1, and ensure engine coolant temperature is 167-185°F (75-85°C). Inspect fast idle cam position. Center of mark "A" should be aligned with mark "C", and cam follower's lever should not be touching fast idle cam. See Fig 1. If fast idle cam operates as specified, go to step  5. If fast idle cam does not operate as specified, go to next step.

  3. Fast Idle Cam Inspection & Adjustment

    Allow engine to cool until engine coolant temperature is 68-86°F (20-30°C). Inspect fast idle cam position. Center of mark "A" should be aligned with mark "B". See Fig 1. If fast idle cam position is not as specified, adjust by turning adjusting screw. Go to next step.
  4. Start engine and warm until engine coolant temperature is 167-185°F (75-85°C). Inspect fast idle cam position. Center of mark "A" should be aligned with mark "C", and cam follower's lever should not be touching fast idle cam. If fast idle cam operates as specified, go to next step. If fast idle cam does not operate as specified, replace thermo element and retest.

  5. Check Ignition Timing

    Start engine and warm to normal operating temperature. Turn ignition off. Disconnect TP sensor harness connector. See Fig 2. Start engine. Check ignition timing using a timing light. Ignition timing should be 13-17 degrees BTDC. Adjust ignition timing by turning distributor. Go to next step.

  6. Check Base Idle Speed

    Check idle speed. Base idle speed should be 650-750 RPM with transmission in Park or Neutral. If idle speed is as specified, go to next step. If idle speed is not as specified, adjust by turning idle speed adjusting screw. See Fig 3. Go to next step.

  7. Check Closed TP Switch Idle Position

    Turn ignition off. Reconnect all harness connectors. Start engine and warm to normal operating temperature. Turn ignition off. Disconnect TP switch harness connector. See Fig 2. Insert a.008" (.20 mm) feeler gauge between throttle adjusting screw and throttle drum as shown in illustration. See Fig 4.
  8. Check continuity between TP switch terminals No. 5 and 6. See Figure. Continuity should exist. Remove.008" (.20 mm) feeler gauge, and insert.012" (.30 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. TP Sensor Idle Position Adjustment

    Ensure engine is at normal operating temperature. Loosen TP sensor bolts. Remove.012" (.30 mm) feeler gauge, and insert.010" (.25 mm) feeler gauge. Open and close throttle. Continuity should not exist while closing throttle. If continuity exists, turn TP sensor body counterclockwise until continuity does not exist.
  10. Remove.010" (.25 mm) feeler gauge, and insert.008" (.20 mm) feeler gauge. Slowly rotate TP sensor body clockwise until continuity exists, then tighten TP sensor bolts. Ensure continuity exists when throttle is closed and does not exist when throttle is open. Repeat 2 or 3 times. Remove.008" (.20 mm) feeler gauge, and insert.012" (.30 mm) feeler gauge. Ensure continuity does not exist when throttle is closed. Repeat 2 or 3 times. Go to next step.

  11. Reset TP Sensor Idle Position Memory

    Remove feeler gauge. Reconnect all harness connectors. 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 5 seconds. Repeat 20 times. Go to next step.

  12. Check Target Idle Speed

    Check idle speed. Target idle speed should be 700-800 RPM with transmission in Park or Neutral. If idle speed is as specified, go to next step. If idle speed is not as specified, adjust by turning idle speed adjusting screw. See Fig 3. Go to next step.

  13. 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 - QUEST article.
Fig 1: Identifying Fast Idle Cam Alignment Marks (Quest)
G00051921Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating TP Sensor & TP Switch Harness Connectors (Quest)
G00042089Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 3: Locating Idle Speed Adjusting Screw (Quest)
G99B50915Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 4: Checking TP Switch Idle Position (Quest)
G00051922Courtesy of NISSAN MOTOR CO., U.S.A.
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