Engine - High Idle Upon Initial Shift Into Drive Gear

88chevy07
Number: 88-190-6E

Section: 6E

Date: APRIL, 1988
Subject: HIGH IDLE ON INITIAL SHIFT INTO DRIVE GEAR


Model and Year: 1987/88 S/T/M TRUCK WITH 2.5L (VIN E) ENGINE
TO: ALL CHEVROLET DEALERS

Customer comments of a higher than normal engine idle RPM upon initial drive gear engagement that decreases within a few seconds, may be because of an ECM software condition. This drive only RPM condition is similar to a "carbureted fast idle" or "high cam step" level.

The above condition may be brought on by repeated engine "revving" in park/neutral or by a rolling/stopping action while in neutral. This condition will only occur in a non A/C vehicle or with A/C off.



The following ECM calibration PROMs will help overcome the above condition:
* The suspect ECM part number can be checked by using a Tech 1 scanner.

In conjunction with this type of comment, stored diagnostic codes should be looked at as well as the symptom section of the Service Manual.

Use applicable labor operation and time.