POSSIBLE BURNT S/P TIPS DETONATION INDUCED PREIGNITION. Pontiac Parisienne (Canada) 1985

For 1990-2009 cars

# POSSIBLE BURNT S/P TIPS DETONATION INDUCED PREIGNITION

1984-85 PARISIENNE WITH 5.0L LG4 ENGINE

"Please discard bulletin 85-6(Gasoline)-63, dated 4186 due to revision in the spark plug gap setting."

Customer comments may be received regarding pre-ignition/detonation on 1984-85 models with 5.0L LG4 engine. Detonation is most likely to occur when the vehicle is pulling a grade or in extended periods of heavy load operation and may lead to pre-ignition which can be recognized by melted spark plug center electrode.

If normal diagnostic procedures do not correct the cause of the detonation, the original spark plugs (R45TS) should be replaced with R43CTS plugs, P/N 5613810. These plugs have a colder heat range but are equipped with a copper core to reduce plug fouling.

Spark plug gap should be set at .035".

Use applicable labor time and operation number.

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.