Supercharger - Outlet Gasket Split, Air Leak

File In Section: 6E - Engine Fuel & Emission

Bulletin No.: 77-65-15

Date: May, 1997

Subject:
Idle Surge or Increased Idle
(Replace Supercharger Outlet Gasket)

Models:
1992-95 Buick Park Avenue
1995 Buick Riviera
1992-95 Oldsmobile Ninety Eight
1995 Oldsmobile LSS
1992-95 Pontiac Bonneville
with 3800 Supercharged Engine (VIN - 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

P/N Description

24507608 Gasket - Supercharger
Outlet

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation Description Time Labor

J5905 Gasket, Use Published
Supercharger - Labor Operation
Replace Time