IDLE SPEED UNSTABLE SURGE ON DESCENDING GRADES

MODEL AND YEAR: 1987 BERETTA, CAVALIER, CORSICA WIIH 2.0L, L-4 ENGINE (VIN CODE 1)

Some early production vehicles may experience one or both of the conditions listed below. The described conditions can be improved by replacing the engine calibration PROM with a new service PROM.

CONDITIONS

o Vehicle experiences a surge when descending long grades with the throttle slightly open. This is more pronounced at higher elevations and can be present in both automatic or manual transmission equipped vehicles.

o Engine idle speed fluctuates up to 300 RPM on vehicles equipped with manual transmissions. This is more prevalent on higher mileage units.

SERVICE PROMS AND THEIR APPLICATIONS

Cavalier Automatic Trans. Serv PROM #16071643 Cavalier Manual 4-Speed Trans. Serv PROM #16071647 Cavalier Manual 5-Speed Trans. Serv PROM #16071652 Beretta/Corsica Automatic Trans. Serv PROM #16071656 Beretta/Corsica Manual 5-Speed Trans. Serv PROM #16071661

Use applicable Labor Time Guide for PROM replacement.

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.