Engine - Miss/Poor Driveability

File In Section: 6E Engine Fuel & Emission

Bulletin No.: 87-65-27

Date: December, 1998

Subject:
Engine Miss/Poor Driveability Symptoms
(Install Opti-Spark (ABITS) Distributor Assembly Service Kit)

Models:
1994-96 Buick Roadmaster
1994-96 Cadillac Fleetwood
1992-96 Chevrolet Corvette
1993-97 Chevrolet Camaro
1994-96 Chevrolet Caprice
1993-97 Pontiac Firebird/Trans Am
with 4.3L or 5.7L Engine (VINs W, P, 5 - RPOs L99, LT1, LT4)

Condition

Some vehicles with the above engines and equipped with the Opti-Spark (ABITS) ignition system may exhibit an engine miss and/or poor driveability symptoms.

Cause

The (ABITS) cap and rotor may exhibit carbon tracking, cracking, or water intrusion which can cause an engine miss and/or poor driveability symptoms.

Correction

Perform strategy-based diagnosis. If it is determined that the ABITS cap and/or rotor is the source of the concern, then a service kit may be now implemented instead of a complete ABITS assembly.

Parts Information

There are two (2) variations of Opti-Spark Distributors. It will be mandatory to identify which type is to be serviced for proper parts procurement.





1. Opti-Spark Distributor II (Pin Drive - WITH positive vent system) can be identified by the intake manifold vacuum hose connection (3), air intake duct hose connection (4), or non-splined pin drive (1). Refer to Figure 1.





2. Opti-Spark Distributor I (Splined Drive - WITHOUT positive vent system) can be identified by the splined pin drive (1), or the lack of intake manifold vacuum hose connection and air intake duct hose connection. Refer to Figure 2.





Important:
it is necessary to use tool J 39997 (or equivalent) for the Distributor Cap Screws and tool J 39998 (or equivalent) for the Rotor Screws. Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation Labor Time

J452O (B/D/F Cars) Use published labor
J436O (Y Car) operation time