Automatic Transmission problems of the 2007 GMC Acadia

Driving my 2007 GMC Acadia. Went to pass a slower vehicle, pressed on the accelerator to pass and the transmission went haywire and the accelerator stuck. I had to put the car in neutral to get it stopped. The rpms were in the 4000s. Then the acceleration would stop and start again over to 4000. Luckily when I passed the vehicle there were no cars in front of me or I would have had a major accident with the acceleration out of control. I took it to the dealer and they told me that two of the timing chains were very worn and there was an issue with the clutch pressure control with harsh shifts in drive range 3rd and/or 5th gear. This is the second time I have had problems with this issue. The first time the GMC dealer 'flashed' (reprogrammed) the transmission, even though it was not acting up when the car was taken into the shop. If this issue is not addressed "properly", I believe someone somewhere will be injured or killed. The condition my vehicle exhibited leaves me with a very uneasy feeling.

Driving my 2007 GMC Acadia. Came upon a busy state highway. After coming to a stop, I saw an opening and pressed on the accelerator to cross the 4 lane road. When I pressed the accelerator, the car just started to creep out into traffic. The engine rpm's increased, but the car was moving at walking speed. It was obvious that the transmission had not shifted back into 1st gear. I tried to manually shift into low, but it did not respond. I finally was able to get it going fast enough to have it pick up some speed to get across the lanes of traffic. On the way home, every time I came to a stop, the car acted the same way upon acceleration. The only way I was able to get the car to go back into 1st gear was to shut the car off and restart it. Even doing that, it only lasted until the next time I stopped. After letting the car sit over night, it performed fine the next day. This is the second time I have had problems with this issue. The first time the GMC dealer 'flashed' (reprogrammed) the transmission, even though it was not acting up when the car was taken into the shop. I spoke with a car dealer at the shop, and he owned the same vehicle. His transmission has been 'reflashed' 6 or 7 times for the same issue. If this issue is not addressed "properly", I believe someone somewhere will be injured or killed. The condition my vehicle exhibited leaves me with a very uneasy feeling (I. E. When I press the accelerator, I expect the car to move). If reflashing the transmission (1, 2, 3, 4. . . 7 times) does not fix the problem, then maybe something different needs to be done.

I leased a 2007 Acadia on 5-24-07 and shortly after taking delivery I felt there was something wrong with the transmission and the way it shifted, I notified the dealership about the problem and took it in for repair. They told me they couldn't get the problem to repeat and felt there was nothing wrong. On 6-14-07 I took a trip to florida from michigan and got 11 miles into georgia and the transmission decided to shift into 1st gear going 70 mph. I managed to get off the road and was wondering what went wrong. I pushed the onstar button and they got me to a dealership (newton GMC in tennessee), they done a quick computer check for error codes and found many codes that they didn't know what they were but they said it was related to the transmission. I left the Acadia with them and finished my trip to florida in a Ford pickup. After 2 weeks the dealership got the ok from gm to replace the transmission. I am still having problems with the new transmission shifting correctly. As of 9-17-07 there is a new software update the dealerships will have to correct the shifting problems for 2007 models, the 2008 models already have the new software in them when they leave the assembly plant. This problem may be on the 2007 Saturn outlook because they have the same transmission.