ENGINE STALL AND/OR HES. AFTER COLD START. Pontiac Firebird 1989

Models Affected: 1987-89 FIREBIRD MODELS W/2.8L MPFI AND A/T

Some owners of 1987-89 Firebird models with a 2.8L multi-port fuel injected (MPFI) engine (VIN Code S) and an automatic transmission may experience an engine stall after cold start or during a Park to Drive/Reverse maneuver immediately after the cold start, or a cold driveaway hesitation. These conditions may occur during emission ambient temperatures of 65-80 degrees Fahrenheit.

To service either of these conditions, complete the diagnostic procedures per Section 6 of the Service Manual. Specific attention should be given to the following items and repair as required.

1. Loose or leaking air duct between mass airflow (MAF) sensor and throttle body.

2. Low minimum air rate.

IMPORTANT: Reference Section 6E3-C2 of the Service Manual for the proper minimum air rate adjustment procedure and specification.

3. Openings in the EGR transfer tube.

IMPORTANT: The EGR transfer tube connects the EGR valve assembly to the exhaust manifold.

4. The correct service PROM calibration for 1987-88 vehicles.

IMPORTANT: Reference the chart below for 1987-88 2.8L Firebirds with four-speed automatic transmission, service PROM part numbers:

1987-88 1987-88 Emission *PROM Service PROM BROADCAST Model System I.D. Part Number CODE ----- ------ ----- ----------- ---- Firebird Federal 0531 16130708 APFU Firebird Calif. 0521 16130698 APFT

* PROM identification as read with a service scan tool.

5. Fouled spark plugs or loosely attached ignition wires at the distributor or spark plug (diagnosis to be completed using an oscilloscope or equivalent).

6. A plugged or damaged catalytic converter system.

IMPORTANT: Inspect exhaust system for any restrictions, per Section 6F of the Service Manual.

7. A defective cold start injector (reference Section 6E3-C2 of the Service Manual).

8. A plugged, leaky, or damaged fuel injector (reference Section 6E3-C2 of the Service Manual.

IMPORTANT: Fuel injectors should hold 20-40 psi fuel pressure for a period of 20 minutes after engine off. An injector balance test will detect plugged or damaged injectors.

If the stall or hesitation condition persists, after a thorough inspection has been completed, then replace the PROM and install an air injection service kit. The PROM will allow a richer fuel mixture, for improved driveability, and the air injection reaction (A.I.R.) system will allow the richer system to pass emission requirements. The A.I.R. system hardware and detailed installation instructions may be obtained by ordering service kit, P/N 10115773 from GMSPO. Refer to the following chart to obtain the new service PROM part number.

Emission PROM Service PROM Model System I.D. Part Number ----- ------ ---- ----------- Firebird California 6191 16136124 Firebird Federal 6231 16136128

IMPORTANT: The above service PROMs and A.I.R. system parts are for a 2.8L Firebird models with an automatic transmission only.

After installation of the A.I.R. service kit has been completed, a new vehicle emission control label should be installed on the vehicle. Reference the chart below for the proper emission label part number.

OLD LABEL NEW LABEL YEAR MODEL PART NUMBER EMISSION SYSTEM PART NUMBER ---- ----- ----------- --------------- -----------

1987 Firebird 10051418 Federal 10145423 10051482

1987 Firebird 10051422 California 10145425

1988 Firebird 10055679 Federal 10145427 10055680

1988 Firebird 10055684 California 10145429

1989 Firebird 12016635 Federal 10145431

1989 Firebird 10116639 California 10145433

IMPORTANT: Current label must be removed and the surface cleaned prior to installation of the new label.

Parts are currently available from GMSPO.

Labor Operation Number: T1420 NOTE: Requires Zone Approval.

Labor Time 6.6 Hours (1987-88)

6.8 Hours (1989)

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.