Engine - Idle Speed Instability/Surge

Number: 87-23

Section: 6E

Date: NOV., 1986
Subject: PROM CHANGE TO IMPROVE IDLE
STABILITY AND SURGE ON DESCENDING GRADES

Model and Year: 1987 BERETTA, CAVALIER, CORSICA WITH 2.0L, L-4 ENGINE (VIN CODE 1)


TO: ALL CHEVROLET DEALERS


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

^ 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.

^ 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.