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Q: Car stops accelerating, motor stalls, what can I do?

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My 2010 Ford Fusion ran fine for the first 70,000 miles but now has started to randomly decelerate when my foot is still on the accelerator. This is a serious problem. The car stalled out at a couple of times when I stopped, which I thought was unusual for an automatic. But, I didn’t think anything serious was happening. Now I think those things are related and something is broken that is making the accelerator not work. How can I properly diagnose this problem?

A: Before the advent of modern computer contro...

Before the advent of modern computer controls, the driver of a vehicle was in direct connection with many of the systems they were controlling. Power accessories (locks, windows, etc) were directly linked to the switches at the driver’s finger tips. The accelerator pedal used a cable to transfer the driver’s force to opening the throttle blades. In the increasing push for efficiency, modern vehicles use sensors and actuators to communicate the driver’s requests, removing the direct links. In the event of a malfunction, the output performed may be vastly different what the driver requested. I believe the best strategy given your symptoms would be having a certified technician inspect your Fusion, and look for signs of failures in the electronic throttle control (ETC) system. Any faults will almost certainly be logged as diagnostic trouble codes, and the technician can begin diagnosis from there. Because the ETC system is responsible for countless cycles of opening and closing the throttle blade, it wears out just like any other part. Thankfully, the parts in this system are relatively inexpensive, and if properly diagnosed, can be changed in less than an hour.

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