ENGINE SURGE / ROUGH IDLE LONG CRANK - REPL. PCM PROM

SUBJECT: ENGINE SURGE AT LOW SPEED, ROUGH IDLE AFTER COLD START, OR LONG CRANK TIMES AFTER A HOT SOAK (REPLACE PCM PROM)

VEHICLES AFFECTED: 1993 "V" MODELS

CONDITION:

Some owners of 1993 Cadillac Allantes may experience one of the following conditions: . Engine surge at low speed . Rough idle after cold start . Long crank times after a hot soak

CORRECTION:

These conditions may be corrected by replacing the PCM PROM calibration. Check the PCM PROM I.D. using on-board diagnostics. If the PROM I.D. (parameter PD99) in the vehicle is lower than 2103, replace the PROM with P/N 16179000 (broadcast code AZYD).

To repair this condition use the following procedure:

1. Prior to changing PROM record transmission oil life remaining by using PCM override PS1 5.

2. Replace PCM PROM per published Service Information Manual procedure in Section 6E-A.

3. Turn ignition on. Diagnostic trouble code 80 (TP Sensor/idle Learn Not Complete) should be set.

4. Go into PCM overrides and slew transmission oil life via override PS1 5 to the value recorded in step 1.

5. Turn the ignition off for 20 seconds. This will force TP Sensor learn to occur.

6. To perform idle learn, warm up the engine to 85 degrees C coolant temperature. Then idle the vehicle in gear with the climate control in the "ECON" mode with foot on the brake and not touching the throttle for 60 seconds or until diagnostic trouble code 80 becomes a history code ("Service Engine Soon" goes out).

7. If diagnostic trouble code 80 will not become a history code, perform steps 5 and 6 again. If still not successful, check the throttle linkage for any binding conditions and for accelerator pedal interference (with floor mats, etc.) which could be causing the closed throttle position switch to remain open or for a brake switch malfunction.

NOTE: This PCM PROM contains a new PCM diagnostic trouble code P080, TP Sensor/Idle Learn Not Complete. This diagnostic trouble code will be set any time the TP Sensor or idle learn values have not been stored in the PCM. Performing the TP Sensor and idle learn procedures listed in this bulletin and in the appropriate Service Information Manual will cause diagnostic trouble code POBO to become history. Clear PCM diagnostic trouble codes when the TP Sensor and idle learns are completed.

For vehicles repaired under warranty use:

Labour Operation: J6364

Labour Time: 0.6 Hrs

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.