For 1990-2009 cars

# Engine Miss/Poor Driveability Symptoms

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 Engines (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 the rotor may show 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.

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

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

Distributor | P/N | Application | Kit Contents
--- | --- | --- | ---
Opti-Spark I (Spline Drive) (No Vent) | 10457735 | 92-94 Y 93-94 F | Distributor cap, rotor, screws, and washers
Opti-Spark II (Pin Drive) (Positive Vent) | 10457293 | 94-96 B,D 95-96 Y 95-97 F | Distributor cap, rotor, cover, screws and washers

Important: It is necessary to use tool J 39997 (or the equivalent) for the distributor cap screws and tool J 39998 (or the equivalent) for the rotor screws.

Parts are currently available from GMSPO.

### Warranty Information

Use the following information for vehicles repaired under warranty:

Labor Operation | Labor Time
--- | ---
J4520 (B/D/F cars) | Use published labor operation time
J4360 (Y car)