Sierra 1500 2WD V6-4.3L (2008)
Spark Plug: All Technical Service Bulletins
Ignition System - MIL ON/Runs Rough/Misfire DTC's Set
TECHNICAL
Bulletin No.: 09-06-04-018
Date: March 20, 2009
Subject:
Malfunction Indicator Lamp (MIL) Illuminated, Engine Runs Rough, Intermittent Misfire, DTC P0300-P0306 (Inspect/Replace Spark Plug Wire
Assemblies/Spark Plugs)
Models:
2008 Chevrolet Express, Silverado
2008 GMC Savana, Sierra
With 4.3L Engine (VIN X - RPO LU3) Only
Condition
Some customers may comment that the MIL lamp is illuminated.
Some customers may comment that the engine runs rough.
The technician may find DTCs P0300-P0306 set as current or in history.
Cause
Some engines covered by this bulletin may have been equipped with spark plug wire boots that do not provide a sufficiently robust dielectric seal (to the
spark plug ceramic insulator) to withstand the high voltage required to fire the spark plugs. The dielectric seal is formed by an interference fit of the
silicone boot stretched over the spark plug ceramic insulator. If this dielectric seal is not sufficient to withstand the high voltages required to fire the
spark plugs, the high voltage will track down the surface of the ceramic spark plug insulator (between the boot and ceramic insulator) to the metal spark
plug shell (hex), resulting in a misfire event. When this arcing occurs, a carbon track is established along the path of the arc, which causes subsequent
arcing to occur at progressively lower voltages. The resulting misfire events can lead to an illumination of the MIL or a rough running engine.
Correction
Important
DO NOT reprogram the ECM, or replace any of the following components: the ECM, ignition coils, fuel injectors, any HO2S sensors or the catalytic
converter for this condition.
Technicians are to inspect the spark plug wire boot for the proper length, and the spark plugs as indicated in the following procedure.
1. Connect a scan tool and start the engine. Determine which cylinder(s) are affected by the misfire condition.
2. Disconnect and remove the affected spark plug wire assemblies and the corresponding spark plugs from those cylinders. Refer to Spark Plug Wire
Replacement and Spark Plug Replacement in Service Information (SI).
Spark Plug Wire Boot Inspection
3. Compare or measure the length of the affected spark plug wire boot(s) to that of one taken from spark plug wire kit, P/N 89060518 for the correct
length of approximately 69.5-72 mm (2.73-2.83 in) as indicated in the above illustration.
4. If any of the spark plug wire assemblies that were removed from the engine has a spark plug boot that is greater in length than 72 mm (2.83 in), or
greater in length than a comparable spark plug boot taken from the spark plug wire kit, then proceed to replace all of the spark plug wire
assemblies.
Spark Plug Carbon Tracking Inspection
