K 1500 Yukon Denali AWD V8-6.0L VIN U (2002)
Intake Air Plenum Gasket: Customer Interest
Engine - Rough Idle/Misfire/MIL ON/DTC P0300
Bulletin No.: 05-06-04-029A
Date: June 24, 2005
TECHNICAL
Subject:
Flexible Fuel (RPO L59) Rough Idle, Misfire, MIL DTC P0300
(Install Intake Manifold Gaskets With Teal Green Gasket Material)
Models:
2002-2004 Chevrolet Silverado, Suburban, Tahoe
2002-2004 GMC Sierra, Yukon, Yukon XL
with 5.3L Engine and Flexible Fuel (VIN Z - RPO L59)
This bulletin may apply to the following engines using regular fuel: 4.8L, 5.3L, 6.0L (VINs V, T, P, U, N - RPOs LR4, LM7, LM4, LQ4, LQ9).
Supercede:
This bulletin is being revised to add additional diagnostic information. Please discard Corporate Bulletin Number 05-06-04-029 (Section 06 -
Engine/Propulsion System).
Important:
Always begin your diagnosis with the Diagnostic System Check - Engine Controls (SI Document ID # 1289827) for any MIL or driveability concern.
The Diagnostic System Check directs you to the next logical step in your diagnosis. Follow the instructions in this bulletin should the rough idle,
misfire, or DTC P0300 diagnostic procedure point to an air leak in the intake manifold gasket. Following the published diagnostic procedures will
improve diagnostic accuracy and support our fix it right the first time approach.
Condition
Some customers may comment that the vehicle may have a rough idle, misfires and/or a MIL illuminated with a stored DTC P0300.
Cause
The L59 engine is calibrated for ethanol fuel (E85). Due to the low volatility of ethanol, the PCM provides higher fuel flow through the injector, which
may pool on the upper manifold to head gasket material. Overtime (usually 12 months and longer), the gasket material may degrade resulting in an
unmetered air leak.
Correction
Replace the upper intake manifold gaskets with the teal green gasket material, P/N 89017589.
Important:
Do not replace the upper intake manifold gaskets with the original orange gasket material, P/N 17113557.
Inspect Intake Manifold to Cylinder head Deck for Warpage
