POOR COLD DRIVEABILITY HESITATION,STALL,STUMBLE

POOR COLD DRIVEABILITY

MODELS AFFECTED: SOME 1986 CENTURYS, SKYLARKS AND SOMERSETS --------------- EQUIPPED WITH AUTOMATIC TRANSMISSIONS AND 2.5L ENGINES (VIN CODES "R AND U")

Some customer comments on poor cold driveability may be received on 1986 Centurys, Skylarks and Somersets equipped with 2.5L Engines (VIN Codes "R and U"). The comments may range from hesitations, sags, and stumbles, to engine miss.

These conditions may be caused by PROM calibrations that are too lean under some cold start driveaway conditions.

Should a vehicle with any of the above described cold driveability conditions be received, and normal service procedures do not correct the condition, the following service PROMS are available from GMWDD:

SERVICE PROM MODEL ENGINE TRANS. AXLE ------- ----- ------- ------ ----

16062202 Century Coupe & 2.5L (VIN Code R) 3-Speed Auto. 2.39 Ratio Sedan

16064305 Century Coupe, 2.5L (VIN Code R) 3-Speed Auto. 2.84 Ratio Sedan, and Wagon

16060865 Skylark and 2.5L (VIN Code U) 3-Speed Auto. 2.84 Ratio Somerset

Use applicable labor operation number and labor time for PROM replacement.

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.