Engine - Runs Rough/MIL ON/DTC P0300 Set

File In Section: 6E - Engine Fuel & Emission

Bulletin No.: 87-65-12

Date: March, 1998

Subject:
Engine Runs Rough, MIL Illuminated, DTC P0300 Set
(Replace Plug Wire)

Models:
1997-98 Buick Regal
1998 Chevrolet Lumina, Monte Carlo
1998 Oldsmobile Intrigue
1997-98 Pontiac Grand Prix
with 3800 or 3800 Supercharger Engine (VINs K, 1 - RPOs L36, L67)

Condition

Some owners may comment about a rough running engine and the MIL (Malfunction Indicator Lamp) is illuminated. After installing a scan tool, the technician determines that DTC (Diagnostic Trouble Code) PO3OO is set. Technician further determines that the suspect cylinder(s) has a split boot on the spark plug wire at the spark plug end of the wire.

Cause

The grease inside the spark plug boot may deteriorate the rubber causing the boot to split and eventually miss direct the spark to ground.

Correction

1. Inspect all spark plug boots for splitting at the plug end by removing the wire from the plug and then removing the cylindrical heat shield from the boot. Pinch the rubber boot with your fingers and visually inspect for cracks around the perimeter of the opening.

2. Field data suggests that cylinders 1, 3, and 5, (front bank) are most likely to experience the condition. Therefore, if a split plug wire boot is found on any of these cylinders, replace all the wires on that bank with new wires listed in the Parts Section in this bulletin.

CYLINDERS 2, 4, and 6 (rear bank) ARE TO BE SERVICED INDIVIDUALLY.

Before installing the new wires on the spark plugs, remove any old grease from the spark plugs by wiping them with a clean dry shop towel. The new wires have an improved grease that will not deteriorate the spark plug wire boot. Clear the DTC PO3OO code with a scan tool and verify that the misfire condition has been corrected.

3. If a crack is not found or if the misfire condition persists, then follow DTC P0300 diagnostic aids in the appropriate Service Manual.





Parts Information

Part Number Description Application

12192158 Single Plug Wire 3800
Cyl 4 Supercharger
VIN 1 - RPO L67

12192157 Single Plug Wire 3800 Supercharger
Cyl 5 VIN 1 - RPO L67

12192158 Single Plug Wire 3800
Cyl 6 Supercharger
VIN 1 - RPO L87

Parts are currently available from GMSPO.

Warranty Information





For vehicles repaired under warranty, use the table.