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Jumping Mustang?

It may sound strange but in cold weather especially in the snow, my car will occasionally “jump” and “buck” when I am cruising at a steady speed. The wrench light has only gone on once. When that happened I lost a lot of power and the car would not pick up any speed and was difficult to accelerate without it starting to jerk like crazy. Any idea??

I had a similar incident in an '04 Ford T’bird. I was driving it very aggressively at the time; manually shifting the auto trans., running the motor up to redline, just having a bit of fun. Suddenly the car lost power, seemed to sputter, and sent a lot of jerking through the drive train. I pulled off the road and the car didn’t stop but was barely limping along. When I did stop the idle was erratic. The wrench light had come on at the 1st sign of lost power and jerking. I figured this was bad. I shut off the motor, but I wasn’t sure it would restart. It seemed like maybe something in the motor had come apart.

I let everything sink in and ran through the possible issues and mega repair bills in my mind, and a few minutes later figured I had nothing to loose so I hit the starter. Surprisingly it restarted, ran smoothly, the wrench light didn’t come on and I’ve driven the car about 20K miles since this “event”.

So, what might be happening? I think I overreved the motor, and/or shifted manually into gears the transmission’s controls didn’t want to accept. In effect my imputs were incompatible with what the car’s computer wanted to do and I think I sent the computer controls into a fit.

When something isn’t right there is a “limp” mode in Fords which is supposed to protect the motor from damage, from overheating, over reving, etc. This limp mode isn’t smooth it seems like a few cylinders hit strong, and then it cuts power and this sends the shock waves through the drive train.

Perhaps you had a similar incident with your Mustang. I still drive the T’bird hard at times, but haven’t had a recurrance. Something is putting your Mustang into “limp” mode, the question is what? How often has this happened, and under what circumstances?

It has happened a few times where I would just be cruising along and the car would try to downshift and “jump” into the lower gear. The wrench light had never gone on at this point. About a week ago I was driving just after we had some snowfall and it did the same thing but this time the wrench light came on and I was unable to really get any speed when pressing in the gas. I arrived home and turned the car off. I wasnt sure it would start and I didnt want to do anymore damage if something was wrong (keep in mind I bought the car from a reputable car dedaler and already had to have the transmission rebuilt within 2 years because there was a crack in it). The wrench light was off the following day when I did try to restart it and it was fine. Then this week I started the car to go to work just after we had snow again, and the car did the same thing, but again without the wrench light. I think it is the snow, and this might sound weird, but I read a blog with a man that was having the same problem with his wife’s 2005 mustang. Somehow the snow is maybe getting into something and causing the problem or it may just be the cold. I have taken the car to the mechanic and they cant find anything wrong.