IDLE SURGE OR INCREASED IDLE (REPLACE SUPERCHARGER). Buick Park Avenue 1994

SUBJECT: IDLE SURGE OR INCREASED IDLE (REPLACE SUPERCHARGER OUTLET GASKET)

MODELS: 1992-95 BUICK PARK AVENUE 1995 BUICK RIVIERA 1992-95 OLDSMOBILE 98 1995 OLDSMOBILE LSS 1992-95 PONTIAC BONNEVILLE WITH 3800 SUPERCHARGED ENGINE (VIN 1--RPO L67)

CONDITION:

SOME OWNERS MAY COMMENT ABOUT AN ENGINE IDLE SURGE, HIGH IDLE (800 - 1000 RPM), OR MIL (MALFUNCTION INDICATOR LAMP) ILLUMINATED WITH DTC (DIAGNOSTIC TROUBLE CODE) P0131, P0171 OR 44 SET, DEPENDING ON MODEL YEAR.

CAUSE:

SUPERCHARGER OUTLET GASKET MAY BE SPLIT NEAR THE FRONT OF THE SUPERCHARGER (PULLEY END) CREATING AN AIR/VACUUM LEAK.

DIAGNOSTICS:

INSTALL A SCAN TOOL DEVICE IN THE VEHICLE. TURN AIR CONDITIONER OFF. WARM THE ENGINE UP TO OPERATING TEMPERATURE. WITH THE ENGINE AT IDLE, BRAKE PEDAL DEPRESSED, AND GEAR SELECTOR PLACED IN DRIVE, MONITOR IAC (IDLE AIR CONTROL) COUNTS ALONG WITH LONG/SHORT TERM FUEL TRIM NUMBERS. IF IAC COUNTS ARE LESS THAN 15 AND LONG/SHORT TERM FUEL TRIM NUMBERS ARE GREATER THAN 140, AN AIR LEAK SHOULD BE SUSPECTED. CHECK FOR AND REPAIR ANY AIR LEAKS AROUND VACUUM HOSES, CONNECTIONS, AND VACUUM CONTROLLED DEVICES. IF THE CONDITION IS STILL PRESENT, CHECK FOR AN AIR LEAK NEAR THE FRONT OF THE SUPERCHARGER (PULLEY END). IF AN AIR LEAK IS DETECTED IN THIS AREA, REMOVE THE SUPERCHARGER ASSEMBLY AND REPLACE THE SUPERCHARGER OUTLET GASKET.

CORRECTION:

REPLACE THE SUPERCHARGER OUTLET GASKET WITH AN UPDATED GASKET THAT HAS BEEN REDESIGNED TO PROVIDE BETTER LONG TERM SEALING. THOROUGHLY REMOVE THE OLD GASKET MATERIAL FROM THE INTAKE MANIFOLD AND SUPERCHARGER ASSEMBLY. INSTALL THE SERVICE SUPERCHARGER OUTLET GASKET DRY; USE NO SEALERS.

PARTS INFORMATION:

GASKET - SUPERCHARGER OUTLET 24507608

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR LABOR OPERATION DESCRIPTION TIME J5905 GASKET, SUPERCHARGER - REPLACE USE PUBLISHED LABOR OPERATION TIME FIGURES: 00 ATTACHMENTS: 00

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.