COLD START STALL/HESITATION/ IDLE ROLL/UPSHIFT SAG

SUBJECT: COLD START STALL/ HESITATION IDLE ROLL AND UPSHIFT SAG (DIAGNOSTICS, NEW HEI MODULE AND MEMCAL)

VEHICLES AFFECTED: 1990-92 CHEVROLET CAMARO AND PONTIAC FIREBIRD WITH 3.1L ENGINE (VIN CODE T)

Condition: Some customers may experience Cold Start Stall and/or Hesitation, Idle Roll and/or 1-2 Upshift Sag with their 1990-92 F car.

Cause: System and component variability and electromagnetic interference.

Correction: If any of the subject conditions are found, complete the following procedure:

1. Perform diagnostics, per Section 6E of the Service Manual. Make any adjustments as required, or replace any defective parts associated with the above conditions.

Important: The customer should avoid the use of high octane fuels as they do not increase performance.

2. Replace the High Energy Ignition (HEI) module with a new P/N 16140039, and install a new Mem-Cal from the table, using the Service Manual and attached procedure.

Important: The appropriate model year cartridge must be used to check new MEMCALS.

Broadcast Scanner Part Code I.D. Number Description ---------- -------- -------- ------------ AZTY 1331 16171406 MEMCAL (FED-AUTO)

BAWX 6651 16176864 MEMCAL (NATIONWIDE- MANUAL)

A. Pull the underhood Electronic Control Module (ECM) continuous power fuse or disconnect the battery and leave it disconnected for at least 1 minute.

B. Remove existing Mem-Cal and install a new service Mem-Cal per the latest service procedure.

C. Restore the battery power and place air conditioning controls (if equipped) in the "Off" position.

D. Firmly apply the parking brake and block the drive wheels. Start the engine, and shift the transmission to "Drive".

E. Allow the engine to run until the engine cooling fan has cycled once, or a maximum of 10 minutes.

F. Turn the ignition key to the "Off" position for at least 5 seconds.

G. Start the engine, and shift the transmission to "Drive".

H. Allow the engine to run for at least 5 minutes.

3. If the installation of the new parts does not eliminate the driveability conditions, then the ECM harness and the electrical harness (near the coil bracket) should be inspected for chafing and repaired as required.

For vehicles repaired under warranty use:

Labour Time: 1.2 Hour Add: 0.5 Hour (To inspect and repair wire harness as necessary)

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.