REPEAT INCIDENTS OF CODE 34 MAF SENSOR LOW (NEW PROM)

VEHICLES AFFECTED: 1985 'F' Cars with LB9 5.0L TPI Engine (VIN Code F)

If occurrences of trouble Code 34 (MAF Low) are encountered, the following steps should be taken:

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, Pontiac page 6E3-148).

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

4. If trouble Code 34 is shown to be 'intermittent', a new PROM should be installed as listed below:

Application PROM P/N ----------- -------- Chevrolet With A/C 1227739 Chevrolet W/O A/C 1227740

Pontiac With A/C 1227741 Pontiac W/O A/C 1227742

NOTICE: These service PROMs contain additional calibration changes designed to enhance vehicle driveability. Engine idle speed will be controlled to 650 RPM and the TCC engagement speed will be raised to 65 KPH (41 MPH).

Use applicable labour 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.