Upon acceleration, usually from a complete stop such as accelerating from a stop sign or on a green light, it feels as though the gears do no catch & the car jerks and the RPM's raise but the car stops accelerating. Will also have a "stuttering" or "jerking" while at a complete stop with break pedal being pressed down. I have taken this issue to the dealership as it is still under extended warranty and have been told that everything checked out normal & the mechanic at the dealership was unable to get the vehicle to have such described malfunctions because it is doesn't happen every single time the car is driven. The jerking while driving actually occurs on a daily basis but is sporadic & can jerk you forward due to the sudden loss of acceleration capability, startling and painful because the seatbelt mechanism has engaged in the past.

- Chico, CA, USA

Engine had massive top engine detonation (backfire) with only 7500 miles on new car. Ever since this event the car shudders, stammers, shakes and does not want to accelerate smoothly. The problem varies in daily severity and is always worse in wet, heavy moisture periods. I have taken the car to five (5) different Ford dealerships and they all say there is no problem because there are no codes indicating a problem. One of the Ford dealerships went to great lengths to fix the car but to no avail. They rebuilt the transmission because they thought it was a failure to downshift. They later replaced three different sensors on this ecoboost engine (they said there are 33 different sensors) and this actually gave temporary improvements, but this was also in the very dry dallas summer. As soon as I drove back across Arkansas to Tennessee the car was as bad as before. This car actually gets 14.2 miles per gallon combined driving and it was rated at 18mpg (16city and 21highway). The car averaged 18.6mpg for the 7500 miles prior to the problem. I have put up with this problem for over three years but I have learned to not drive the car in the rain. There are other family cars that I can drive or I would have pulled my hair out. This problem was elevated to Ford customer service on several occasions (4 or 5 different times) and they never took ownership of the problem or the process. There appears to be a firewall established between the Ford technical group and Ford dealership service departments. Several service people complained that they could not contact Ford technical people directly and that it required a failure code entry into the service system without solution to facilitate contact with technicians and engineers. No code no problem! I sure am glad they have a code for every situation!

- Lafayette, TN, USA

The contact owns a 2011 Ford Flex. The contact stated that while driving approximately 40 mph, there was sudden reduction of engine power without warning. The vehicle was taken to an authorized dealer where both turbo booster were replaced. Most recently, the failure recurred and one of the turbo booster was replaced by the dealer. The manufacturer was notified of the problem. The approximate failure mileage was 68,260.

- Gaithersburg, MD, USA

Our 2011 Ford Flex we bought "new" in October of 2010. It has all the bells & whistles & had a sticker price of almost $51,000 dollars! this car doesn't like to get wet! it stalls in the snow, rain, car wash & even puddles! it just "shuts down" in the middle of an intersection.....it will "putt putt" & almost stall on highways. We came sooo close to getting killed! ugh....we have taken this car in to (metro Ford in raynham) at least "4" times. The last time was just a couple of months ago & it was there for "4 weeks"! then this was it.........we had to take our 19 yr old daughter to the er last thurs. She fainted & hit her head hard! this car stalled all the way to the hospital!! we almost didn't make it there!! this car is a lemon!!! we want this car replaced!!!

- Taunton, MA, USA