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Home >> Nissan-Datsun >> 1991 >> Sentra SE-R >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments >> Adjustment >> V6 Idle Mixture >> Maxima, Pathfinder & Pickup

Maxima, Pathfinder & Pickup

  1. Start engine and warm to normal operating temperature. Run engine at 2000 RPM for 2 minutes. Perform self-diagnostic procedure. See G - TESTS W/ CODES article. Check for smooth engine operation.
  2. Check engine idle speed and timing. With idle speed and timing correctly set, locate ECU under passenger's seat (under center of dash, behind center console on Maxima).
  3. Increase engine speed to 2000 RPM for another 2 minutes. Ensure Green LED on ECU goes on and off more than 5 times during 10 seconds with engine running at 2000 RPM. If not, go to step 5).
  4. If Green LED operates as stated, increase engine speed to 2000 RPM, 2 or 3 times. Allow engine to return to idle. Enter and set self-diagnostic system to Mode II. See G - TESTS W/ CODES article. Red and Green LEDs on ECU should blink simultaneously. If so, idle mixture is correct. If not, go to step 10).
  5. Turn off engine and disconnect negative battery cable. Disconnect oxygen sensor and wiring harness from ECU. Using a jumper wire, ground wiring harness (center terminal) at oxygen sensor connector.
  6. Check continuity between terminal No. 19 (terminal No. 29 on Maxima) of ECU wiring harness connector and ground. If no continuity exists, repair or replace wiring harness. Reconnect negative battery cable. Repeat idle speed and ignition timing adjustment procedures and check idle mixture.
  7. If continuity exists, remove oxygen sensor jumper wire and reconnect ECU. Disconnect engine coolant temperature sensor connector. Connect a 2500-ohm resistor to engine coolant temperature sensor wiring harness. Reconnect negative battery cable.
  8. Start engine and warm to normal operating temperature. Increase engine speed to 2000 RPM, 2 or 3 times, then allow engine to return to idle. Check idle mixture (CO% level). See V6 IDLE SPEED & CO LEVEL TABLE  .
  9. If idle mixture (CO% level) is incorrect, go to next step. If idle mixture (CO% level) is correct, replace oxygen sensor. Ensure Green LED on ECU goes on and off more than 5 times during 10 seconds with engine running at 2000 RPM. If so, recheck ignition timing and idle speed. If not, go to next step.
  10. Reconnect oxygen sensor. Perform self-diagnosis and repair procedures for fuel pressure, airflow meter, injectors, and engine coolant temperature sensor. See G - TESTS W/ CODES article.
  11. After checking idle mixture, turn off engine. Remove 2500-ohm resistor from engine coolant temperature sensor wiring harness and reconnect sensor.
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