Engine Controls - Low Speed Deceleration Shudder
TSB SB08-02-S001Issue Date: FEBRUARY 2008
LH6 Engine Low Speed Deceleration Shudder, Chuggle Or Pulsation
Affected Vehicles
2006 Isuzu Ascender with 5.3L Engine and 2WD Only
Service Information
Condition:
Some customers may comment on the following low speed deceleration shudder, chuggle or pulsation conditions:
Shudder feels like a brake pulsation and/or chuggle on deceleration from approximately 40 km/h (25 mph) to 24 km/h (15 mph).
Shudder will continue if brakes are released and the vehicle coasts in 40 km/h (25 mph) to 24 km/h (15 mph) speed range.
Shudder is significantly diminished or eliminated if A/C is "Off" due to reduced engine load.
Shudder is eliminated if vehicle is put in D3 mode, which disables 4 cylinder mode (4 cyl mode is permitted when trans is automatically in 3rd or 4th gear, but disabled when PRNDL is placed in the 3rd position).
Selectable Service Calibration Number
IMPORTANT:
Use this selectable service calibration Only for vehicles with low speed deceleration shudder, chuggle and/or pulsation experienced at high temperature and low altitude. A slight increase in fuel consumption may occur.
The title line states "New calibration to address vehicle shudder during decel between 25 and 15 mph, feels like brake roughness. Should be used for complaint only as some loss of performance and fuel economy may occur".
Correction:
Reprogram ECM.
Service Procedure
ATTENTION:
The following service ECM calibration update may slightly increase fuel consumption and should only be used if the customer commented on the shudder conditions outlined in this Service Bulletin. Most vehicles will never experience this shudder.
Reprogram the ECM with the latest calibrations if the above concern is encountered. An updated ECM calibration is now available to address this concern. This calibration, or any that follow, is designed to address this concern. Refer to Service Programming System (SPS) using the appropriate Service Manual procedures. As always, make sure your Tech 2 is updated with the latest software version.
Warranty Claim Information
Always refer to the Isuzu Service Policy Procedure Manual for specific details on warranty coverage and policies. Reference published Labor Time Guide for claim processing, if applicable.
Disclaimer