Envoy 2WD V6-4.3L VIN W (1998)
Idle Speed: All Technical Service Bulletins
PROM - Engine High Idle/Flare When Shifting Gears
File In Section: 6E Engine Fuel & Emission
Bulletin No.: 76-65-07
Date: February, 1998
Subject:
Engine High Idle/Flare when Shifting Gears
(Perform Flash Calibration)
Models:
1998 Chevrolet and GMC S/T; C/K Models with 4.3L Engine
(VINs X, W - RPOs LF6, L35) and Manual Transmission (RPOs - MG5, M5O)
Condition
Some owners may report that the engine exhibits a high idle or flare when shifting gears or disengaging the clutch such as when slowing down or
stopping.
Cause
If following steps 1, 2 and 3 of strategy based diagnostics did not reveal the cause, high idle or engine flare may be the result of additional Idle Air
Control (IAC) air that is learned into the stall saver calibration.
Vehicle operation at low road speeds 16-24 km/h (10-15 mph), in a high gear (5th), causes the engine to lug down below the stall saver threshold. The
off idle stall saver calibration for these engines is approximately 500 rpm.
This situation can be experienced during city driving maneuvers, especially in hilly terrain, when the driver does not downshift the transmission and
forces the engine rpm under the stall saver threshold.
During this condition, the IAC opens to a calibrated level in an attempt to raise the engine rpm above the stall saver threshold. This level of IAC airflow
will cause idle flare if the vehicle is driven out of the lugging condition (ie: downshifting) without first coming to an idle. Idling first would allow the
additional idle air to be learned back to a normal level.
The new calibrations reduce the number of stall saver counts that can be learned in.
Correction
Refer to the table for the applicable calibration change. Perform programming per the latest Techline Information for programming procedures.
Important:
The calibrations listed are FLASH calibrations and are not available from GMSPO. They are available on 1997 Techline CD Disc 22 and later.
Warranty Information
For vehicles repaired under warranty, use:
