For 1990-2009 cars

# ENG.ROUGH/STRAY IGN. PULSE RE-ORIENTING DISTRIBUTOR

SOME EARLY PRODUCTION 1983 OMEGAS WITH 2.8L (VIN CODE X OR Z) ENGINE MAY EXHIBIT ENGINE ROUGHNESS CAUSED BY STRAY ELECTRONIC SIGNALS RE- CEIVED BY THE DISTRIBUTOR MODULE. THESE STRAY SIGNALS PRODUCE A FALSE (HIGH RPM) TACH REFERENCE PULSE TO THE ECM. THE ROUGHNESS IS MOST NOTICEABLE AT IDLE, BUT MAY PERSIST DURING ACCELERATION AND AT CRUISING SPEEDS. ROUGHNESS CAUSED BY THE FALSE REFERENCE PULSE CAN BE ALLEVIATED BY RE-ROUTING THE LEAD WIRES AS FOLLOWS: 1. DISCONNECT PRIMARY COIL LEADS AT THE COIL. 2. DISCONNECT THE ECM FOUR (4) WIRE CONNECTOR. 3. REMOVE THE IGNITION WIRES AND COIL WIRE FROM THE DISTRIBUTOR CAP. 4. REMOVE THE DISTRIBUTOR CAP. 5. CUT A 230 MM (9 INCH) LENGTH OF .350 I.D. CONDUIT (PART NO. 8919354) AND INSTALL ON THE DISTRIBUTOR PRIMARY LEADS. CUT AN 85 MM (3.3 INCH) LENGTH OF THE ABOVE CONDUIT AND INSTALL ON THE FOUR (4) WIRE ECM LEADS AT THE DISTRIBUTOR. 6. CRANK THE ENGINE UNTIL THE WHITE TIMING MARK ON THE TORSIONAL DAMPER AND THE "O" ON THE TIMING INDICATOR ARE IN ALIGNMENT AND THE DISTRIBUTOR ROTOR IS IN THE NO. 1 POSITION. 7. REMOVE THE DISTRIBUTOR CLAMP SCREW AND HOLD-DOWN CLAMP. 8.A. SLOWLY RAISE THE DISTRIBUTOR UNTIL THE ROTOR JUST STOPS TURNING CLOCKWISE. B. TURN THE DISTRIBUTOR BASE AND ROTOR CLOCKWISE AT THE SAME TIME, UNTIL THE LEAD WIRES ARE IN A 7 O'CLOCK POSITION WHEN VIEWED ALONG THE CENTERLINE OF THE ENGINE FROM THE REAR FACE OF THE ENGINE. BE SURE THE DISTRIBUTOR IS ROTATED ENOUGH SO THAT THE LEAD WIRES CLEAR THE COIL BRACKET HOLD-DOWN BOLT. 9. REINSTALL THE DISTRIBUTOR. LOOSELY REINSTALL HOLD-DOWN CLAMP AND CLAMP SCREW. 10. REINSTALL THE DISTRIBUTOR CAP. 11. REINSTALL THE IGNITION WIRES AND COIL WIRE IN THEIR ORIGINAL TERMINAL POSTS. IF THE NO. 3 IGNITION WIRE IS TOO SHORT, SWITCH IT WITH NO. 4 IGNITION WIRE. 12. ROUTE THE PRIMARY COIL LEAD UNDER THE RIGHT SIDE (WIREEES 1, 3, 5) IGNITION WIRES AND ATTACH TO THE COIL. 13. SET THE TIMING TO SPECIFICATIONS ON THE VEHICLE EMISSION CONTROL INFORMATION LABEL AND TIGHTEN THE DISTRIBUTOR HOLD- DOWN CLAMP SCREW. 14. RECONNECT THE ECM FOUR (4) WIRE CONNECTOR.

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.