HESITAION,COLD DRIVE-AWAY CODE 34, TCC(PROM RELEASE)

Model and Year: 1985 CAMAROS WITH LB9 5.0L, V8 ENGINES (VIN CODE F)

TO: ALL CHEVROLET DEALERS

A new Service Prom 1227739 with AC and 1227740 without AC has been released for 1985 Camaro 5.0L TPI engines which will address the following customer comments:

o "Chuggle" or "Shudder" when torque converter engages at lower speeds. This new Prom will raise the TCC engagement point to 41 mph.

o Hesitation on acceleration during cold drive away. New Prom should be installed and minimum idle speed should be reset to 500 RPM as described in the 1985 Shop Manual, Page 6E3-145.

o Repeated incidents of Code 34 (Mass Airflow Sensor Low) prior to installing new Prom perform the following procedures:

1. Check for engine vacuum leaks

2. Set minimum idle speed to 500 RPM as described in your 1985 Shop Manual. (Chevrolet Page 6E3-145).

3. Perform diagnostic check for Code 34 found in your 1985 Shop Manual. (Chevrolet Page 6E3-101).

4. If trouble Code 34 is shown to be "Intermittent", a new PROM should be installed.

NOTICE: These service PROMS contain calibration changes designed to enhance vehicle driveability. Engine idle speed will be raised to 650 RPM when IAC motor is connected, and the TTC engagement speed will be raised to 41 mph.

Use applicable labor time and operation numbers.

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.