COLD START STALL-CHUGGLE AT 35-45 MPH WITH TCC

Subject: COLD START STALL-CHUGGLE AT 35-45 MPH W/TORQUE CONVERTER CLUTCH ENGAGED REV. CALIB. MEM-CALS

Models Affected: 1989-91 BONNEVILLE MODELS W/3800 ENGINE

Some owners of 1989 through 1991 Bonneville models equipped with the 3800 (Code C) Engine may experience one or both of the following conditions:

o Engine does not stay running on initial cold start.

o Chuggle at 35-45 mph with torque converter clutch engaged.

The two conditions are independent of each other, yet it may be possible for both conditions to exist on one vehicle.

Follow the information outlined under the individual heading for that condition:

ENGINE DOES NOT STAY RUNNING ON INITIAL COLD START

If the vehicle's basic engine controls and fuel systems are operating properly, it is important for the technician to familiarize themselves with information contained in Service Bulletin Number 91-6-9 "Recommended Fuels For Non-Turbo Port Fuel Injection Engines". If the condition cannot be repaired by changing fuel or using currently published service and diagnostic procedures, it may be necessary to install a revised calibration mem-cal. Install mem-cals listed in Table A for this condition only.

CHUGGLE AT 35-45 MPH WITH TORQUE CONVERTER CLUTCH ENGAGED

Proceed with the diagnostic flow chart (Figure 1) to aid in identifying the possible cause of the condition.

Note: The new revised calibration mem-cals may slightly affect fuel economy (usually less than 1 mile) Be sure to advise the vehicle owner of this fact.

ENGINE DOES NOT STAY RUNNING ON INITIAL COLD START AND CHUGGLE AT 35-45 MPH AND WITH TORQUE CONVERTER CLUTCH ENGAGED -------------------------------------------------------------- Should owners' comments indicate both conditions exist. Follow steps outlined in both procedures. The two conditions are independent of each other. If it is determined that a new revised calibration mem-cal is necessary to correct both conditions, select mem-cals listed in Table B.

Note: The new revised calibration mem-cals in Table B may affect fuel economy. Be sure to advise the vehicle owner of this fact.

TABLE "A" ========= SCANNER ID WITH BROADCAST SERVICE YEAR MODEL AXLE RATIO MEMCAL INSTALLED CODE PART ------ --------- ---------- ---------------- ------ -------- 1989-91 Bonneville 2.84 5614 AYLA 16165848 NATL/CALIF

1989-91 Bonneville 2.97 5634 AYLC 16165839 NATL/CALIF

1989-91 Bonneville SSE 3.33 5654 AYLF 16165834 NATL/CALIF

TABLE "B" ========= SCANNER ID WITH BROADCAST SERVICE YEAR MODEL AXLE RATIO MEMCAL INSTALLED CODE PART ------ --------- ---------- ---------------- ------ -------- 1989-91 Bonneville 2.84 5624 AYLB 16165843 NATL/CALIF

1989-91 Bonneville 2.97 5644 AYLD 16165829 NATL/CALIF

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

Labor Operations: T0500 Labor Time .7 hr. (Replace mem-cal) .2 hr. (Add to complete chuggle Diagnostic Flow Chart only.

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.