BAMA_LTZ_HOE
Member
I have noticed that when I'm on the interstate and the engine goes to 4 cyl mode, I can feel a slight vibration through the driveline. The vibration is similar to the feel of a rear tire out of balance. When it switches back to 8 cyl mode it is smooth again. It is really a small vibration and I'm probably the only person in the truck that notices it. My mom has a 2008 Yukon and I haven't noticed it in her truck. My truck has 78,000 miles on it. Has anyone else had this issue.
---------- Post added at 08:02 AM ---------- Previous post was at 07:58 AM ----------
LOOKS LIKE A GOOGLE SEARCH ANSWERED MY OWN QUESTION>>>
Service Information 2010 GMC Truck Sierra - 4WD | Sierra, Silverado VIN C/K Service Manual | Document ID: 2405891
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#06-06-05-001D: Information on Change in Exhaust Tone or Sound for Active Fuel Management (AFM) System Equipped Engines in Three or Four Cylinder Mode - (Feb 23, 2010)
Subject: Information on Change in Exhaust Tone or Sound For Active Fuel Management (AFM) System Equipped Engines in Three or Four Cylinder Mode
Models: 2007 Buick Rainier
2007-2009 Buick Allure (Canada Only), LaCrosse
2007 Chevrolet Monte Carlo
2007-2009 Chevrolet TrailBlazer
2007-2010 Chevrolet Avalanche, Impala, Silverado, Suburban, Tahoe
2010 Chevrolet Camaro
2007-2009 GMC Envoy Denali
2007-2010 GMC Sierra, Yukon, Yukon XL, Yukon Denali
2007-2009 Saab 9-7X
with Active Fuel Management System Vortec® GEN IV 5.3L, 6.0L or 6.2L V8 Engine RPOs LMG, LC9, LY5, LH6, L76, L77, LFA, LZ1, LS4, L94, L99 or 3.9L V6 Engine RPOs LZ8, LZG
Some customers may comment on a change in the exhaust note or tone when an Active Fuel Management System equipped engine is in 3 or 4 cylinder mode. Some drivers may also notice a very slight vibration in either the accelerator pedal, floor pan and/or the steering wheel. This is a normal condition for Active Fuel Management System equipped vehicles and no repairs should be attempted.
Customer Information on Active Fuel Management
When the Active Fuel Management System is enabled, physical changes take place within the engine that allow it to run as a 3 or 4 cylinder motor with accompanying additional fuel savings. The change in exhaust tone is expected as all sound from the exhaust is the result of combustion in the engine. The ability to perceive these changes in sound are kept to very minimal levels as the Active Fuel Management System is only activated during steady state/near steady state driving or during coast down. In both of these situations, the load on the engine is minimal and general exhaust volume (sound) is low.
You may give a copy of this bulletin to your customer.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
© 2010 General Motors. All rights reserved.
---------- Post added at 08:02 AM ---------- Previous post was at 07:58 AM ----------
LOOKS LIKE A GOOGLE SEARCH ANSWERED MY OWN QUESTION>>>
Service Information 2010 GMC Truck Sierra - 4WD | Sierra, Silverado VIN C/K Service Manual | Document ID: 2405891
--------------------------------------------------------------------------------
#06-06-05-001D: Information on Change in Exhaust Tone or Sound for Active Fuel Management (AFM) System Equipped Engines in Three or Four Cylinder Mode - (Feb 23, 2010)
Subject: Information on Change in Exhaust Tone or Sound For Active Fuel Management (AFM) System Equipped Engines in Three or Four Cylinder Mode
Models: 2007 Buick Rainier
2007-2009 Buick Allure (Canada Only), LaCrosse
2007 Chevrolet Monte Carlo
2007-2009 Chevrolet TrailBlazer
2007-2010 Chevrolet Avalanche, Impala, Silverado, Suburban, Tahoe
2010 Chevrolet Camaro
2007-2009 GMC Envoy Denali
2007-2010 GMC Sierra, Yukon, Yukon XL, Yukon Denali
2007-2009 Saab 9-7X
with Active Fuel Management System Vortec® GEN IV 5.3L, 6.0L or 6.2L V8 Engine RPOs LMG, LC9, LY5, LH6, L76, L77, LFA, LZ1, LS4, L94, L99 or 3.9L V6 Engine RPOs LZ8, LZG
Some customers may comment on a change in the exhaust note or tone when an Active Fuel Management System equipped engine is in 3 or 4 cylinder mode. Some drivers may also notice a very slight vibration in either the accelerator pedal, floor pan and/or the steering wheel. This is a normal condition for Active Fuel Management System equipped vehicles and no repairs should be attempted.
Customer Information on Active Fuel Management
When the Active Fuel Management System is enabled, physical changes take place within the engine that allow it to run as a 3 or 4 cylinder motor with accompanying additional fuel savings. The change in exhaust tone is expected as all sound from the exhaust is the result of combustion in the engine. The ability to perceive these changes in sound are kept to very minimal levels as the Active Fuel Management System is only activated during steady state/near steady state driving or during coast down. In both of these situations, the load on the engine is minimal and general exhaust volume (sound) is low.
You may give a copy of this bulletin to your customer.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
© 2010 General Motors. All rights reserved.
