For 1990-2009 cars

# TIP IN HESITATION AND STUMBLE CANADIAN OLDSMOBILE

THE FOLLOWING CHANGES ARE BEING RECOMMENDED TO IMPROVE DRIVEABILITY CHARACTERISTICS AFTER COLD START-UP AT TEMPERATURES LESS THAN 15C. BEFORE IMPLEMENTING THE FOLLOWING PROCEDURES, ENSURE THE VEHICLE IS ADEQUATELY TUNED (IDLE SPEEDS, SPARK TIMING, VACUUM BREAK, ETC.) AND THE IDLE PROPANE ENRICHMENT IS WITHIN THE RECOMMENDED 40 + 20 RPM RANGE. 1.THE LEAN SAG IS RELATED TO THE CHOKE PULL-OFF RATE, AND A MODIFICATION TO SLOW THIS ACTION WILL IMPROVE THE CONDITION. A REVISED CHOKE HOUSING HAS BEEN INCORPORATED INTO THE 1982 MODELS WHICH PROVIDES THE NECESSARY RATE CHANGE BY RESTRICTING THE HOT AIR FLOW THROUGH THE HOUSING (0.059 INCH VACUUM ORIFICE). TO PROVIDE A CORRESPONDING REVISION FOR 1981 MODELS, REPLACEMENT OF THE CHOKE HOUSING IS RECOMMENDED. THE 1982 CHOKE HOUSING KIT P/N 17068979 CAN BE OBTAINED FROM GM PARTS DEPARTMENT FOR THIS PURPOSE. THE PROCEDURE WILL INVOLVE USING THE ORIGINAL CHOKE COVER AND COIL ARM WITH THE NEW HOUSING KIT. 2.TO PROVIDE THE ADDITIONAL SPARK ADVANCE DESIRABLE DURING WARM-UP OPERATION, A TRAPPED SPARK SYSTEM WAS INCORPORATED INTO THE CALIBRATION, WHICH IN 1981 WAS TEMPERATURE DEACTIVATED BY A 100F COOLANT T.V.S. TO IMPROVE THIS ACCELERATION SAG CONDITION, REMOVE THE SPARK TVS P/N 3030951 AND REPLACE WITH THE 1982 120F VERSION, P/N 3032006. IT IS RECOMMENDED THAT THE ABOVE CHANGES BE INCORPORATED TOGETHER, AS NEITHER ALONE WILL MAKE A SIGNIFICANT CONTRIBUTION TOWARDS CORRECTING THE CONDITION. FOR THIS REASON, THE REVISIONS HAVE BEEN CERTIFIED TO MEET CANADIAN EMISSION REGULATIONS TOGETHER AS PART OF THE SYSTEM. ADDITIONAL CONDITION: SOME EARLY PRODUCTION VEHICLES EQUIPPED WITH 5.0L (307) CANADIAN OLDSMOBILE ENGINES MAY EXPERIENCE AN ENGINE STUMBLE CONDITION WHICH IS MOST PREVALENT IN A MINIMAL THROTTLE APPLICATION. VEHICLES UTILIZING CARBURETORS PRIOR TO 8/29 (242) MAY BE CORRECTED AS FOLLOWS. SEE FIGURE 1 FOR CARBURETOR DATE CODE LOCATION. 1.ENSURE ENGINE IS IN PROPER TUNE BY MAKING ADJUSTMENTS ACCORDING TO THE PROCEDURE AND SPECIFICATIONS ON THE VEHICLE EMISSION CONTROL LABEL. 2.INSTALL PART NUMBER 52350705 TEE ASSEMBLY (VACUUM BLEED). PLACE THE TEE IN THE EGR VACUUM SIGNAL LINE NEXT TO THE EGR VALVE, BY CUTTING THE LINE AND INSERTING THE BLEED AS IN FIGURE 2. DIRECTION OF FLOW THROUGH THE BLEED IS NOT IMPORTANT. 3.IF OFF-IDLE OPERATION IS STILL UNACCEPTABLE, CHECK THE PROPANE ENRICHMENT. IF RPM INCREASE IS NOT WITHIN 40+10 RPM, REMOVE IDLE MIXTURE SCREW CAPS AND RESET. FOLLOW THE PROCEDURE OUTLINED IN THE SERVICE MANUAL FOR PERFORMING THIS OPERATION. WHEN RESET OPERATION IS COMPLETE RE-SEAL MIXTURE SCREWS WITH SILICONE RTV SEALER, TO PREVENT TAMPERING AND FUEL VAPOUR LOSSES. 4.IF CONDITION STILL PERSISTS AND ALL ENGINE OPERATIONAL ADJUSTMENTS ARE IN ORDER, THROTTLE BODY REPLACEMENT WILL BE NECESSARY. IF A VEHICLE EQUIPPED WITH A CARBURETOR BUILT BETWEEN THE EARLY AND FINAL PRODUCTION REVISION DATES (8/29 - 10/16) EXHIBITS THIS SAME CONDITION, STEPS 1, 3 AND 4 MAY BE UTILIZED FOR SERVICE CORRECTION.

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.