Engine Controls - Cold Start Stall/Hesitation Diagnosis
89Pontiac22Bulletin Number: 89-6-72
Reference Number: 836550
Publish Date: 10/89
Subject: ENGINE STALL AND/OR HESITATION AFTER COLD START (DIAGNOSIS AND SERVICE KIT P/N)
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:
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.
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.
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)