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On the 2002 to present Altimas, the idle speed is controlled by the ECU; there is no manual adjustment like they had on the old cars. According to the FSM, the No load* (in P or N position) idle speed is 650 +/- 50 rpm. If you need to bring the idle speed back to spec, there is a procedure called "Idle Air Volume Learning" (IAVL) which is a function of the ECU to learn the idle air volume that keeps the engine idle speed within the standard specific range. It must be performed under any of the following conditions:

• Each time the electric throttle control actuator or ECU is replaced.
• Each time the throttle body harness connectors are unplugged/replugged.
• Idle speed or ignition timing is out of specification.

Disconnect the negative battery terminal for 30 seconds to reset the ECU. Do not perform the relearn procedure if the check engine light (CEL) is still on and codes related to the mass airflow sensor, manifold absolute pressure, or incorrect idle speed are found. If everything is in order, we can begin.

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TOOLS NEEDED: stopwatch or timer showing seconds.

ACCELERATOR PEDAL RELEASED POSITION LEARNING

Do not start engine in this procedure.

1. Make sure the accelerator pedal is fully released.
2. Turn ignition switch ON and wait at least 2 seconds.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Turn ignition switch ON and wait at least 2 seconds.
5. Turn ignition switch OFF and wait at least 10 seconds.

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THROTTLE VALVE CLOSED POSITION LEARNING

Do not start engine in this procedure.

1. Make sure the accelerator pedal is fully released.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Make sure throttle valve moves during above 10 seconds by confirming the operating sound.

Rectangle Font Parallel Pattern Slope


IDLE AIR VOLUME LEARNING

1. First, bring the engine/transmission to normal operating temperature, 70-100°C or 158-212°F; do this by driving on the road for not less than 30 minutes; warming up the car in the garage doesn’t cut it! Next turn off all accessories such as the air conditioning, rear window defogger, radio, and heater blower to prevent a load on the engine which would cause erroneous positioning of the throttle plate. Finally, make sure the front wheels of the vehicle are in the neutral position pointing straight ahead. We are now ready to perform the required relearn procedure.
2. Selector lever: P or N (CVT), neutral (M/T), Battery voltage: More than 12.9V (At idle), engine coolant temperature: 70-100°C or (158-212°F), turn off all electrical powered stuff, wheels turned straight.
3. Shut off engine and wait at least 10 seconds.
4. With the foot off the brake pedal, turn ignition switch to the ON position(not START) or push ignition switch button to the ON position(two taps) and start the stopwatch at the same time.
5. When the stopwatch is at 3 seconds, press & release the accelerator pedal 5 times fully and quickly within 5 seconds.
6. Wait 7 seconds or more then fully press the accelerator pedal and hold for approximately 20 seconds or more until the CEL stops blinking and stays ON constantly.
(note: If the CEL never starts blinking, then something is not working and you'd better start over again).
7. Within 3 seconds after the CEL stays on constantly, release the accelerator pedal.
8. Immediately start the engine and let it idle. It may still likely be a high-rev/pulsating idle.
9. Let it run for no less then 20 seconds, then rev the engine a few times.
10. With the foot on the brake pedal, shift into Drive. Idle should now go down under 1000 rpm. Shift to Park or neutral again, and the car should find its regular idle speed. Operation will be normal except the CEL might still be on. It may disappear soon on its own, or you can do the following:

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EASY RESET OF CHECK ENGINE LIGHT (CEL)

1. Turn the key OFF and wait at least 10 seconds
2. Turn the key ON (no ignition), wait 3 seconds, then press & release the accelerator pedal 5 times fully and quickly within 5 seconds.
3. Wait 10 seconds, then fully press the accelerator.55942
4. After about 12 seconds, CEL should go off then start blinking. As soon as it starts blinking, release the accelerator.
5. Wait 10 seconds, then fully press the accelerator.
6. Wait 10 seconds, then fully release the accelerator.
7. Turn the key to OFF, then immediately start the engine. The CEL should now be off.

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(special note: If the IAVL fails to complete because of high idle due to other conditions, unplug one or more fuel injector harness connectors to bring down the idle speed.)
 
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