ENGINE MISSFIRE-HARD THROTTLE 2.0 TURBO/ REVISED PLUG GAP

MODELS AFFECTED: 1987 2.OL LT3 (VIN CODE M) ENGINE

Some engines in subject vehicles may misfire under hard throttle, such as during turbo boost conditions. The miss is caused by excessively high ignition system demand voltage of the high gap (.060") spark plug and combustion conditions.

The misfire is repairable by installing a .035" gap spark plug, Part Number 5613820 (R42XLS, a 1986 turbo spark plug).

For future spark plug service on this vehicle, a page of peel-off labels is included with this bulletin (to dealers only). This reference label should be placed on the same mounting surface and near the current vehicle emission control information, "Tune-Up" label.

Use applicable labor operation.

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.