EVAP System - Knocking Noise Just Above Idle

Classification:
EC01-033

Reference:
NTB02-020

Date:
February 18, 2002

1999-02 FRONTIER AND 2000-02 XTERRA
KNOCKING NOISE ABOVE IDLE (800-1100 RPM)

APPLIED VEHICLES:

1999-2002 Frontier (D22) with VG33E - NOT Supercharged
2000-2002 Xterra (D22) with VG33E - NOT Supercharged

SERVICE INFORMATION

If an applied vehicle exhibits the following symptom:

^ Slight noise that sounds like engine "knock" is heard just above engine idle speed (800-1100 rpm) with the engine under a slight load, and the noise cannot be detected over 1100 rpm.

The cause may be normal pulsating noise coming from the EVAP purge solenoid valve and piping (in the engine compartment) transferring into the passenger cabin.

However, use the Service Procedure in this bulletin to reduce the noise, if it should occur.

SERVICE PROCEDURE

1. Start and run the engine for at least one minute.

2. Use CONSULT-II to view the status of the "Closed Throttle Position Switch" (CTPS).

3. Set the Parking Brake, then perform the following;

^ For vehicles with Automatic Transmission, with your foot on the brake, place the A/T gear selector in "D."

^ For vehicles with Manual Transmission, depress the clutch and select any gear.

4a. While viewing CTPS status, open the throttle just enough to change the CTPS status from "On" to "Off."

NOTE:
This will allow the EVAP Purge Volume Control Solenoid Valve to begin operating.

4b. Listen closely for a slight "knocking" noise. If "knocking" noise is heard;

1) Put the transmission in "Neutral" (M/T) or "Park" (A/T).





2) Disconnect the electrical connector to the EVAP Purge Volume Control Solenoid Valve (see Figure 1).

3) Listen again for "knocking" noise by repeating steps 3, 4a, and 4b.

^ If "knocking" noise is still heard, this Service Bulletin does not apply. Consult the appropriate Service Manual for further diagnosis.

^ If "knocking" noise is now not heard, shut off the engine and proceed to step 5.





5. Remove the Hose Clamps from the EVAP Purge Hose (see Figure 2).

6. Remove the EVAP Purge Hose (see Figure 2).

NOTE:
Set aside the two Purge Hose Clamps for use in step 7.





7. Install the Vacuum Tank and Hose kit listed in the PARTS INFORMATION section (see Figure 3).

NOTE:
Use the hose clamps set aside in step 6 to secure the replacement parts.

8. Reconnect the electrical connector to the EVAP Purge Volume Control Solenoid Valve (see Figure 1).

9. Repeat steps 3, 4a, and 4b to verify the slight "knocking" noise is gone.





PARTS INFORMATION

CLAIMS INFORMATION





Submit a Primary Failed Part (PP) line claim using the claims coding shown.