Engine - Cold Start Stall/Hesitation/Idle Roll

91pontiac03

Bulletin Number: 91-6-32
Reference Number: 136505
Publish Date: 3/91


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

Models
Affected: 1990-91 FIREBIRD MODELS W/3.1


Condition:

Customers may experience Cold Start Stall and/or Hesitation, Idle Roll and/or 1-2 Upshift Sag with their 1990-91 Firebird model.

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.

2. For vehicles built prior to the VIN breakpoints indicated below, 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.

VIN BREAKPOINTS

FEDERAL ML241599

CALIFORNIA ML241869


Broadcast Scanner Part
Code I.D. Number Description

AYCH 4261 16164296 MEM-CAL (FED.)
AYCF 4251 16164292 MEM-CAL (CALIF.)

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 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.

Parts are currently available from GMSPO.

Labor Operation Number : T1707

Labor Time : 1.2 Hour

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