SPARK PLUG FOULING ROUGH IDLE LOW SPEED MISFIRE

SOME 1981 4.4 LITER ENGINES ARE ENCOUNTERING ROUGH IDLE AND LOW SPEED MISFIRE DURING COLD DRIVEAWAY AT LOW AMBIENT TEMPERATURES. A NEW CALIBRATION (PROM) HAS BEEN RELEASED WHICH REDUCES AVAILABLE FUEL DURING THE OPEN LOOP PORTION OF CONTROL, RESULTING IN IMPROVED COLD DRIVEABILITY. THE FOLLOWING PROCEDURE SHOULD BE USED TO CORRECT THE ABOVE STATED CONDITIONS. 1.REPLACE THE PRODUCTION PROM IN THE ECM WITH THE NEW PROM (SEE CHART BELOW). FOLLOW PROM REPLACEMENT PROCEDURE IN SERVICE MANUAL SUPPLEMENT #ST-329-81A PAGES 6E1-52 AND 6E1-53. VEHICLE TYPE A COUPE, SEDAN, AS PROM # 1225318 VEHICLE TYPE B WAGON PROM # 1225319 VEHICLE TYPE A WAGON, EL CAMINO PROM # 1225320 VEHICLE TYPE "F" COUPE PROM # 1225321 VEHICLE TYPE B COUPE, SEDAN PROM # 1225322 2.THE FOLLOWING SHOULD ALSO BE CHECKED AT THIS TIME: A) SPARK PLUGS FOR CARBON FOULING AND LIQUID FUEL WETTING B) ENGINE OIL FOR FUEL CONTAMINATION AND PROPER LEVEL C) VACUUM BREAK ADJUSTMENT (SHOULD BE 25F) D) ENGINE TIMING AND FAST IDLE ADJUSTMENT PER VEHICLE EMISSION LABEL

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.