COLD DRIVEABILITY/HOT STALL DIAGNOSIS (USE REVISED PARTS)

SUBJECT: COLD DRIVEABILITY DIAGNOSIS (USE REVISED PARTS)

VEHICLES AFFECTED: 1989-91 'M' CAR (SPRINT/FIREFLY) 1.0L ENGINE (VIN CODE 6)

Various cold driveability concerns or hot deceleration stall may be resolved by installation of appropriate updated parts as indicated below:

If the vehicle experiences a cold, extremely rough idle (often described as a "floating", non-cylinder specific miss) and rough running on acceleration, as well as a possible hot deceleration stall, install revised cylinder head, P/N 96065427 plus 6 revised lash adjusters, P/N 5235455 per Service Manual procedures. Installation of a new camshaft is at dealer discretion and should be based on the presence and degree of wear, scratching or pitting of the cam contact area of the original lash adjusters. DO NOT reuse the original cylinder head bolts - install 8 new head bolts, P/N 96059992.

If the vehicle has normal idle quality after a cold start, but has a smooth hesitation on cold acceleration, or if the vehicle starts and runs good cold but after approximately 0.2 KM( 1/8 mile) of driving begins to lose power with the appearance of running over-rich, install an applicable revised calibration ECM as indicated below:

Transmission Emission Part Number ------------- -------- ------------- M/T FED 30009394 A/T FED 30009395

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.