B4000 SE Cab Plus 4 4WD V6-4.0L SOHC (2001)
Valve Spring: Customer Interest
Engine - MIL ON/DTC P0300 (Misfire) Set
Bulletin No: 01-012/02
Last Issued: 04/11/2002
Subject:
B4000 TRUCK 4.0L SOHC ENGINE - MIL ILLUMINATED WITH DTC P0300
APPLICABLE MODEL(S)/VINs
2001-2002 B4000 (4.0L SOHC engine)
DESCRIPTION
Some 2001-2002 B4000 vehicles with a SOHC 4.0L engine may have a Malfunction Indicator Lamp (MIL) "ON" with a Diagnostic Trouble Code
(DTC) of P0300 Random Misfire.
The DTC may set when the engine is operated at high RPM's (4800 RPM and higher) and a misfire is detected. The misfire code may be due to exhaust
valve springs hanging open due to intermittent high exhaust system back pressure and valve spring resonance during hard acceleration.
Modified valve springs are available to repair this concern.
REPAIR PROCEDURE
1.
Verify customer concern and MIL on with DTC P0300 stored.
2.
Check Freeze Frame Data to determine if the misfire occurred above 4800 RPM:
-
If the misfire was detected above 4800 RPM, proceed to STEP 3.
-
If the misfire was detected below 4800 RPM, continue diagnosing the source of the misfire according to procedures found in Workshop
Manual (section 01-01).
3.
Replace ALL (6) Exhaust Valve Springs and all (6) Intake Valve Springs with the modified replacement valve springs using the Workshop Manual
procedure in 2001 4.0L Engine Workshop Manual (Section 01-10).
NOTE:
2001 B-Series 4.0L Engine Workshop Manual is available on MNET P/N 9999-95-226D-01.
NOTE:
Replace all valve springs as a set in order to maintain proper valve train dynamics.
4.
Clear all existing DTC's.
5.
Verify repair.
PART(S) INFORMATION
