ENG. STALL AFTER HOT RESTART/ COLD START & COLD ENG. HES.

Models Affected: 1987-88 6000 AND GRAND PRIX W/2.8L (VIN W)

Some 1987 6000 models and 1988 Grand Prix models equipped with a 2.8L V-6 engine may experience a cold start stall, a stall after start with a warmed-up engine or a stall during deceleration.

A repeated stall after hot restart may be caused by residue accumulating inside the throttle body bore, behind the throttle plate, which limits the air flow past the throttle plate in the idle position. The hesitation concern may be due to a lean electronic control module (ECM) fuel calibration. The cold start stall may be due to a lean ECM calibration, low engine idle speeds, the loss of fuel pressure, or loose electrical connections at the ignition coil and/or the mass airflow sensor.

Customer comments may be repaired as follows:

1. Perform normal service procedures as outlined in the shop manual for the repair of engine stall or hesitation.

2. Verify that all electrical connections such as at the ignition coil and mass airflow sensor are secure.

NOTICE: LOOSE/POOR ELECTRICAL CONNECTIONS AT ALL SENSORS AND ECM METRI-PAK CONNECTORS CAN BE A PROBLEM ANYWHERE ON THE ENGINE. INTERMITTENT CONNECTION CAN PRODUCE STALLING.

3. Verify that there are no engine vacuum leaks at the manifold absolute pressure (MAP) sensor, positive crankcase ventilation (PCV), exhaust gas recirculation (EGR), or other systems.

4. Verify that the fuel system is functioning properly and has proper fuel pressure.

5. Clean the throttle body bore as specified in Dealer Service Bulletin 87-6-32A.

6. Measure the minimum idle speed and throttle position, and adjust to specifications if required.

7. Measure the Throttle Position Sensor (TPS) voltage and adjust to 0.62-0.67 volts, if required.

8. Replace the ECM MEMCAL, (see chart) using the following installation procedure.

a) Disconnect battery power.

b) Install new ECM MEMCAL calibration.

c) Reconnect battery power.

d) Start vehicle with AC/defroster off and power steering not cramped.

e) Allow vehicle to idle in drive for 6 minutes and until thermostat has opened. This will facilitate learning of base idle.

f) Return vehicle to service.

NOTICE: DO NOT REPLACE THE MEMCAL AND RETURN THE VEHICLE TO THE CUSTOMER WITHOUT PROPERLY COMPLETING THE PREVIOUS SERVICE INSTRUCTIONS (ITEMS 1-7).

WARRANTY INFORMATION

Use applicable labor time and operation numbers.

1987 MODEL YEAR

TRANSAXLE EMISSION SERVICE MODEL TRANSMISSION RATIO/CODE SYSTEM MEMCAL P/N ----- ------------ ---------- ------ ---------- 6000 STE 5-Spd. Man. 3.61 Federal 16140355 6000 SE

6000 Wagon 5-Spd. Man. 3.61 Federal 16140355

6000 3-Spd. Auto 2.84/7CTC Federal 16140350 6000 LE

6000 3-Spd. Auto 3.18/7CXC Federal 16140350 6000 LE

6000 STE 3-Spd. Auto 3.18/7CXC Federal 16140350

6000 4-Spd. Auto. 3.33 Federal 16140352 6000 LE

6000 STE 6000 SE 4-Spd. Auto 3.33 Federal 16140352 6000 Wagon

6000 SE 5-Spd. Man. 3.61 California 16140356

6000 STE 5-Spd. Man. 3.61 California 16140356 6000 Wagon

6000 3-Spd. Auto 2.84/7CTC California 16140353 6000 LE

6000 3-Spd. Auto 3.18/7CXC California 16140353 6000 LE

6000 STE 3-Spd. Auto. 3.18/7CXC California 16140353

6000 4-Spd. Auto. 3.33 California 16140354

6000 STE 6000 SE 4-Spd. Auto 3.33 California 16140354 6000 Wagon

1988 MODEL YEAR

Grand Prix 5-Spd. Man. 3.61 Federal 16141563

Grand Prix 4-Spd. Auto 3.33 Federal 16141562

Grand Prix 5-Spd. Man. 3.61 California 16141565

Grand Prix 4-Spd. Auto. 3.33 California 16141564

(ATTACHMENT A)

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.