If the driveline on this truck were an 80's band, it would be WHAM! Most of the time, the six-speed transmission shifts smoothly and the displacement-on-demand feature operates without drama. However, if you happen to lift your foot off the accelerator at just the right time, the transmission shifts as the engine drops into four cylinder mode and it feels like someone hit the bottom of the truck with a sledgehammer. The transmission slam typically occurs once or twice per trip. Additionally, there are times the engine stays in four cylinder mode longer than it should, leaving you with no power and a lugging engine as you try to accelerate. Supposedly, both of these conditions are normal--there is a TSB that states the engine stays in four cylinder mode to prevent driveline lash and the dealer says the transmission clunk is normal. Considering the transmission shifts constantly and gets slammed periodically, I'm thinking it was a good idea to buy a long extended warranty on this truck. Sadly, I will probably be contemplating a different vehicle when the extended warranty is about to expire.
Update from Feb 28, 2018: The active fuel management (AFM) issues continue to get worse as the truck ages. The truck is now three years old and the AFM insists upon going into four cylinder mode with the slightest lift of the gas pedal. The switch to four cylinders occurs even if the truck is going uphill or driving at 15 mph, causing the truck to lurch and lug as it enters four cylinder mode, bogs, and switches back to eight cylinders. The dealer says the truck has adapted to my style of driving and it is working properly. We have five other vehicles in the family that do not drive poorly, and I drive many rental cars that drive well. I have a 20 mile commute to work with long stretches of 35 mph speed limits, so I can't easily change the way I drive.
I want the truck reset to the way it was when I bought it. The dealer has tried pulling the battery, but that didn't change anything. They say there is nothing else that can be done. I drive with the gearshift in manual mode most of the time, which is insane for a modern vehicle. I don't expect to visit the GM dealership when it is time to replace this truck.
If the driveline on this truck were an 80's band, it would be WHAM! Most of the time, the six-speed transmission shifts smoothly and the displacement-on-demand feature operates without drama. However, if you happen to lift your foot off the accelerator at just the right time, the transmission shifts as the engine drops into four cylinder mode and it feels like someone hit the bottom of the truck with a sledgehammer. The transmission slam typically occurs once or twice per trip. Additionally, there are times the engine stays in four cylinder mode longer than it should, leaving you with no power and a lugging engine as you try to accelerate. Supposedly, both of these conditions are normal--there is a TSB that states the engine stays in four cylinder mode to prevent driveline lash and the dealer says the transmission clunk is normal. Considering the transmission shifts constantly and gets slammed periodically, I'm thinking it was a good idea to buy a long extended warranty on this truck. Sadly, I will probably be contemplating a different vehicle when the extended warranty is about to expire.
Update from Feb 28, 2018: The active fuel management (AFM) issues continue to get worse as the truck ages. The truck is now three years old and the AFM insists upon going into four cylinder mode with the slightest lift of the gas pedal. The switch to four cylinders occurs even if the truck is going uphill or driving at 15 mph, causing the truck to lurch and lug as it enters four cylinder mode, bogs, and switches back to eight cylinders. The dealer says the truck has adapted to my style of driving and it is working properly. We have five other vehicles in the family that do not drive poorly, and I drive many rental cars that drive well. I have a 20 mile commute to work with long stretches of 35 mph speed limits, so I can't easily change the way I drive.
I want the truck reset to the way it was when I bought it. The dealer has tried pulling the battery, but that didn't change anything. They say there is nothing else that can be done. I drive with the gearshift in manual mode most of the time, which is insane for a modern vehicle. I don't expect to visit the GM dealership when it is time to replace this truck.
- tom_oh, Hamilton, OH, US