YukonDenali2015

Just picked up my 2015 Yukon Denali on October 31 and on day three, experienced an issue when accelerating that would cause a thuddering sound from the engine. I immediately headed to the dealer and tried to replicate the problem consistently on the way. I realized that when the V4 mode engaged, this problem would occur. As soon as it went to V8 mode, it would stop. I was able to consistently get this to happen. The service department checked the vehicle in and it sat for most of the day. I explained the problem and exactly how to replicate it and they were able to. I also said this occurred after my FIRST gas fill up. I usually run at least plus (91 octane), but maybe they put in regular or it was bad gas. Their response was that regular is all they use in their vehicles. I had to rent a vehicle from enterprise and then go back at the end of the day to switch it for one of their loaners. They proceeded to troubleshoot for the next three days, waiting each time for GM to instruct them along they way. They performed multiple testing and replaced a few parts to test, all to no avail. They drained the gas and put super in as a last resort. They said the problem was still there. By day 4, I was not satisfied with the progress and told them I was picking the truck up. I was considering getting a second opinion. Besides, the loaner vehicle they gave me was an embarrassment. It made noise in auto mode and slid all over the place in 2wd. It was a Suburban LT and certainly not what I was planning on driving three days after taking delivery of my new truck. I asked for my old truck back as a long shot, a 2011 Yukon Denali, and they said that wasn't possible. So I pick the truck up on day 4 and as soon as I started it, I knew there was a bigger problem. I pulled away from the service shop, drove around the block and pulled back into shop. The truck was ticking like crazy. The lead tech came out and explained that it was bad lifter and that it was related to the original problem. I said I didn't notice the original problem while driving around the block, so maybe the gas change fixed that and from all the troubleshooting, this problem was caused. He said they couldn't do anything else until they scheduled a GM Field Tech to come in to advise and he was supposed to call the following Monday to schedule a visit. They said hopefully by the end of the week he would be there. The END of next week! Which means my truck will be out of service for a total of 12 days before something else even gets attempted. Since this is now a completely different problem than originally brought in for, I said I was leaving it and to put me back into a loaner. They didn't have any and said it was ok to drive it until they got a loaner in. I drove it home and parked it. They called me the following day, today, and said they have a Chevy Cruze coming in on Monday! A Chevy Cruze! They should be ashamed. I spent $75k on this truck, drive it for two days and they want to put me in a Chevy Cruze. And from what I'm gathering from the tech, it will be at least a week until they have a next step in troubleshooting. I am beyond aggravated with this ordeal. The tech said they may need to replace the lifters on one side or both or may need to replace the engine! 300 miles on this truck and they're talking about replacing the engine. I've searched for similar problems and can not find any related. My question to anyone that may know is this, depending on what troubleshooting they did since having my truck, could they have caused more damage than good? What could they have possibly done to cause this valve lifter problem? I feel the original problem could have just been gas related and now it is so much worse. Besides the valve lifter ticking, the truck is driving rough. Shifting and accelerating seem off since they've had it. Although minor, still unacceptable is that there is now grease all over the assisted running boards and interior and they also chipped the windshield since having it. The chrome tipped exhaust is also all scratched up from the exhaust hose and there are scuffs on the mirrors, taillight and rear hatch probably from said exhaust hose! Like I said, I had a 2011 Yukon Denali and loved it. Never a problem in 38 months. This new truck was great for the first two days, but this ordeal has quickly soured that new car experience. This truck was amost impossible to find; black on black, 22" tires, open road package, premium package, enhanced security system...even if I wind up having to get another truck, it will be a difficult task. I've complained relentlessly to both the service and sales managers. They seem frustrated with the situation and I hope they are truely doing all they can to resolve this as quick as possible, but I have my doubts. Any advice from the community?