Engine - Runs Rough/Lack of Power/Knock Noise/MIL ON
File In Section: 6E - Engine Fuel & EmissionBulletin No.: 77-65-30
Date: December, 1997
Subject:
Engine Runs Rough, Lack of Power, Knock Noise, MIL illuminated
(Replace Spark Plugs and Reflash PCM)
Models:
1998 Buick LeSabre, Park Avenue
1998 Oldsmobile Eighty Eight, LS, LSS, Regency
1998 Pontiac Bonneville
with 3.8L Engine (VIN K - RPO L36)
Condition
Some owners may comment that the engine runs rough, has lack of power, has a knock noise, and/or the MIL (Malfunction Indicator Light) is illuminated. The service technician may determine that DTC Diagnostic Trouble Code) P0300 is stored in the PCM (Powertrain Control Module). The service technician further determines that the affected cylinders have eroded spark plug electrodes.
Cause
The ESC (Electronic Spark Control) calibration within the PCM may not control the spark timing properly resulting in pre-ignition. The pre-ignition may cause the spark plug electrodes to erode and produce the customer concern.
Correction
1. Install a scan tool and verify DTC P0300 (engine misfire detected) is set.
2. Note the calibration ID currently in the PCM.
3. Remove all six spark plugs and inspect for eroded electrodes.
4. If no spark plug electrodes are eroded, then reinstall the original spark plugs and continue diagnostics using the P0300 diagnostic chart in the appropriate service repair manual. After all repairs are completed, flash the PCM with the calibration listed under the Parts heading in this bulletin if different than the current calibration as noted in Step 2.
5. If a spark plug electrode is eroded, then install new spark plugs and flash the PCM with the calibration listed under the Parts heading in this Bulletin if different than the current calibration as noted in Step 2.
Parts Information
Spark Plug
SPO P/N AC P/N
25161444 41-921
The new calibrations are available for Techline Tools starting with the 1997 CD 24 release from GM Service Technology Group (STG).
Do not attempt to order the calibration numbers from GMSPO. The calibrations are programmed into the vehicle's PCM via a Techline Tool device.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
J6355 Prom-Reprogramming Use Published
On Car Labor Operation
Time
J4226 Spark Plug - Replace Use Published Labor Operation Time
J4217 Spark Plug - Diagnostics Use Published
Without Replacement Labor Operation Time