Engine Controls - Erratic Poor Idle Quality

Classification:
EC04-002

Reference:
NTB04-015

Date:
February 03, 2004

UNABLE TO MAINTAIN IDLE OR LOW/ROUGH IDLE AT START

APPLIED VEHICLES:
2002-03 Sentra (B15)
2002-03 Altima (L31)

APPLIED ENGINE:
QR25DE

IF YOU CONFIRM:

An applied vehicle has the following symptoms:

^ Engine RPM rises at start and then drops and cannot maintain idle

OR

^ Engine has low/rough idle

AND

^ Engine runs well if the throttle is held open

NOTE:
The above symptoms may occur after an ECM reprogram or the vehicle battery was run down (discharged).

ACTIONS:

^ Conduct the "Engine Running and Warm Up" procedure

^ Perform the "Idle Air Volume Learning (IAVL)" procedure

^ If the IAVL does not finish ("CMPLT"), perform the "Corrected Idle RPM Check". Then, perform the IAVL procedure again.

^ Refer to the Service Procedure for details

IMPORTANT:
The purpose of "ACTIONS" (above) is to give you a quick idea of the work you will be performing. You MUST closely follow the entire Service Procedure as it contains information that is essential to successfully completing this repair.





CLAIMS INFORMATION

SERVICE PROCEDURE

Engine Running and Warm Up

1. If the engine is able to maintain an idle, but is rough or low, then move to step 4.

2. Start the engine and hold the throttle part way open to maintain 1500-2000 RPM at "no-load" for 20 seconds.

IMPORTANT:
Follow step 3 (next step) exactly as described.

3. Release the throttle SLOWLY OVER 5 SECONDS back to the closed-throttle position.

4. Let the engine idle for one minute (even if the idle is rough or low).

5. Make sure the engine coolant is above 70°C before proceeding.

6. Make sure all electrical loads are turned OFF, including A/C, defroster, radio, lights, etc. while performing the following procedures. Also, make sure the engine cooling fans are NOT operating during the following procedures.

Idle Air Volume Learning (IAVL)

7. Connect CONSULT-II to the vehicle.





8. In the [CONSULT WORK SUPPORT] mode, select [IDLE AIR VOL LEARN]. See Figure 1.





9. Press [START] on the "IDLE AIR VOL LEARN" screen. See Figure 2.





10. Press [START] on the "WORK SUPPORT" screen to begin the Idle Air Volume Learning (IAVL) procedure. See Figure 3.

^ The IAVL procedure will take several minutes to complete.





^ CONSULT will display "Please Wait" in the center of the screen while the IAVL procedure is in process. See Figure 4.





^ CONSULT will display "CMPLT" in the top right corner of the screen when the IAVL procedure is finished. See Figure 5.

^ If the IAVL procedure does not finish ("CMPLT"), perform the "Corrected Idle RPM Check" procedure. Then repeat steps 8 through 10 of the IAVL procedure.

11. Confirm the engine correctly starts and idles (after the Idle Air Volume Learning procedure is complete).

12. The repair is complete. Disconnect CONSULT-II from the vehicle.

Corrected Idle RPM Check (only necessary if IAVL did not finish "CMPLT")





1. In the [CONSULT WORK SUPPORT] mode, select [TARGET IDLE RPM ADJ]. See Figure 6.





2. Press [START] on the [TARGET IDLE RPM ADJ] screen. See Figure 7.





3. Check the CORRECTED IDLE RPM (see Figure 8):

a. If the CORRECTED IDLE RPM is "0" (zero), press [BACK] two times, then perform the "Idle Air Volume Learning" (IAVL) procedure.

b. If the CORRECTED IDLE RPM is NOT "0" (zero):

^ adjust the value to "0" (zero) using the [DOWN] key

^ press [UPDATE]

^ press [BACK] two times

^ perform the IAVL procedure.

NOTE:
The CORRECTED IDLE RPM must be at "0" (zero), before you can perform the IAVL.