TA427
08-02-2011, 11:24 AM
#PIP4112J: Sag Or Hesitation On Acceleration (Normal Operation Characteristics) - (Jul 21, 2011)
Subject: Sag or Hesitation on Acceleration (Normal Operating Characteristics)
Models: 2007-2011 Cadillac Escalade, Escalade EXT, Escalade ESV
2006-2009 Cadillac XLR, XLR-V
2007-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2006-2011 Chevrolet Corvette
2007-2011 GMC Sierra, Yukon, Yukon XL
2008-2009 Pontiac G8
Equipped With a Gasoline Engine and Automatic Transmission
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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may comment on a sag or hesitation when accelerating under the following
conditions:
When coasting with a closed throttle and then aggressively applying the throttle. Examples of this maneuver include a rolling stop or a lane change maneuver. In this type of maneuver, even though the accelerator is applied aggressively, the throttle blade is opened slowly for up to 0.7 seconds to help minimize driveline lash and clunking.
Also in a 6L80 or 6L90 (RPOs MYC or MYD) equipped vehicle when making a hard, complete stop with a closed throttle, immediately followed by an aggressive throttle opening the transmission downshifts may not be completed by the time the throttle is opened. As a result approximately 0.5 seconds of zero torque may be commanded to allow the shift to first gear to occur.
Recommendation/Instructions:
Both of the above conditions are a result of Torque Management and both of these conditions should be considered normal and no repairs should be attempted. Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
Subject: Sag or Hesitation on Acceleration (Normal Operating Characteristics)
Models: 2007-2011 Cadillac Escalade, Escalade EXT, Escalade ESV
2006-2009 Cadillac XLR, XLR-V
2007-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2006-2011 Chevrolet Corvette
2007-2011 GMC Sierra, Yukon, Yukon XL
2008-2009 Pontiac G8
Equipped With a Gasoline Engine and Automatic Transmission
--------------------------------------------------------------------------------
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may comment on a sag or hesitation when accelerating under the following
conditions:
When coasting with a closed throttle and then aggressively applying the throttle. Examples of this maneuver include a rolling stop or a lane change maneuver. In this type of maneuver, even though the accelerator is applied aggressively, the throttle blade is opened slowly for up to 0.7 seconds to help minimize driveline lash and clunking.
Also in a 6L80 or 6L90 (RPOs MYC or MYD) equipped vehicle when making a hard, complete stop with a closed throttle, immediately followed by an aggressive throttle opening the transmission downshifts may not be completed by the time the throttle is opened. As a result approximately 0.5 seconds of zero torque may be commanded to allow the shift to first gear to occur.
Recommendation/Instructions:
Both of the above conditions are a result of Torque Management and both of these conditions should be considered normal and no repairs should be attempted. Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.