LIGHT LOAD DETONATION NEW PROM

SOME 1980 B" AND "G" SERIES CARS EQUIPPED WITH A 3.8L V-6 ENGINE, MAY EXHIBIT LIGHT-LOAD DETONATION WHEN DRIVING IN THE 1800 TO 2100 RPM ENGINE SPEED RANGE. 1. AFTER CHECKING ALL ITEMS ON THE DETONATION CHECK LIST BELOW AND ALL CONFIRMED TO BE WITHIN SPECIFICATIONS, A NEW SERVICE PROM, PART NUMBER 1226931 SHOULD BE INSTALLED TO FURTHER ASSIST IN REPAIRING THIS CONDITION. 2. DUE TO TIMING CURVE PROGRAMMING CHANGES WITHIN THIS PROM, THE COLD FAST IDLE SPEED WILL REQUIRE RESETTING TO SPECIFICATIONS, AS INDICATED ON THE TUNE-UP LABEL. IT IS ESSENTIAL THAT ALL ENGINE ELECTRONIC AND FUEL CONTROL SYSTEMS BE CHECKED AND SET TO SPECIFICATIONS BEFORE THE VEHICLE IS RELEASED. DETONATION CHECK LIST - EGR VALVE SYSTEM OPERATION, - IGNITION TIMING, - VACUUM HOSES AND/OR CONNECTION LEAKS, - CARBURETOR FOR LEAN OPERATION "DWELL," - DEPOSITS IN COMBUSTION CHAMBERS, - INTAKE VALVE SEALS NOT SEALING, - THERMAC AIR CLEANER OPERATION, - COOLING SYSTEM PROBLEM OVERHEATING - INCORRECT SPARK PLUGS. - BAD FUEL. - EFE VALVE OPERATION NOTE: PROM 1226931 REPLACES BOTH PREVIOUSLY RELEASED 1224682 AND 1225438 PROMS. THIS BULLETIN ALSO SUPERSEDES INFORMATION PROVIDED IN BULLETIN BUICK 80-T-95A.

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.