ENGINE CHUGGLE AT LOW SPEEDS NEW PROM PACKAGE

Subject: ENGINE CHUGGLE AT LOW SPEEDS (NEW PROM PACKAGE TO RAISE TCC LOCKUP SPEED)

Models Affected: 1990 GRAND AM MODELS W/2.5L AND 3T40 AUTO TRANSMISSIONS

Condition: Some owners of 1990 Grand Am models with 2.5L engines may comment about an engine shudder or chuggle condition when driving at slow speeds in high gear.

Cause: Converter clutch lockup at slow speeds during some driving conditions.

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

1990 Grand Am With 2.5L Engine ------------------------------ (FROM 29 TO 43 MPH)

Usage PROM Pkg. P/N Broadcast Code Scanner I. D. ----- ------------- -------------- ------------- All 16159793 AXCM 9801

Parts are expected to be available on November 26, 1990. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be cancelled as incorrectly ordered while the 400 control is in place.

Labor Operation Number: T0500 Labor Time: .3 Hours

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.