STALL, HES.AFTER COLD START DIAGNOSIS AND PROM P/N'S

1986-87 FIREBIRD MODELS WITH 2.8L (VIN CODE S) MPFI ENGINE AND 4 SPEED AUTOMATIC TRANSMISSION

Some 1986-87 Firebird models with 2.8L MPFI engines and 4 speed automatic transmissions may experience one or more of the following conditions at 40 degrees (F) to 70 degrees (F) ambient temperatures:

Stall after cold start

RPM sag or stall when shifting from neutral to drive immediately after cold start.

Cold driveaway hesitation

To service this condition inspect for the following and repair as necessary.

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

2. Low minimum idle speed. (Specificaiton is 550 plus or minus 50 RPM in drive, automatic transmission.)

3. Openings in the EGR transfer tube.

If the condition persists, check PROM I.D. with scan tool. If the PROM I. D. is not any of the following numbers, replace the PROM with one of the service PROMS listed-in the following chart.

Scan tool reading of PROM I.D.: 8419, 8420, 9891, 9901, 9911, 9921

SERVICE PROM APPLICATION

MODEL SALES AIR CONDITIONING SERVICE PROM ----- ----- ----------------- ------------ 86 Firebird Federal Yes 16080020 Federal No 1228420 California Yes 16080015

87 Firebird Federal Yes/No 16080020 California Yes/No 16080015

NOTICE: THE ABOVE PROMS ARE FOR FIREBIRD MODELS WITH 2.8L PORT FUEL INJECTED ENGINES WITH 4 SPEED AUTOMATIC TRANSMISSIONS.

Use applicable labor time and labor operation numbers.

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.