ENGINE CHUGGLE AT LOW SPEEDS RAISE TCC LOCK-UP SPEED (PROM)

Subject: ENGINE CHUGGLE AT LOW SPEED (RAISE TORQUE CONVERTER CLUTCH (TCC) LOCK UP SPEED)

Models Affected: 1989-91 SUNBIRD W/2.0L, 1989 GRAND AM W/2.5L

This bulletin has been revised to include the 1990 and 1991 Sunbird with 2.0L engine. This bulletin cancels and replaces bulletin 89-6-86 issued 9190.

Condition:

----------- Some owners of 1989-91 Sunbird models with 2.0L and 1989 Grand Am models with 2.5L engines may comment of an engine shudder or chuggle condition when driving at slow speeds in high gear.

Cause:

------- Converter clutch lock up at slow speeds during some driving conditions.

Correction:

------------ A new PROM package has been released which raises the TCC lockup speed to the following:

1989 - 1991 Sunbird with 2.0L

From 23 to 39 MPH Usage PROM Pkg. P/N Broadcast Code Scanner I. D. ----- ------------- -------------- -------------- All 16157159 AWSP 7171

1989 Grand Am with 2.5L

From 29 to 43 MPH Usage PROM Pkg P/N Broadcast Code Scanner I.D. ----- ------------ -------------- ------------ All 16157765 AWDT 7781

Parts are currently available from GMSPO.

Labor Operation Number: T0500 Labor Time: .4 - Grand Am .3 - Sunbird

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.