Q: I have a 2008 Ford F-150 2WD 5.4-liter V-8 with 25,000 miles on it. Sometimes when coming to a stop at a light, the truck wants to accelerate. The rpms rev up and the truck doesn't want to stop. I've run a couple red lights because of this. I know my foot is not on the gas and brake at the same time. I have read some forums online, and other people are having the same problem. I've had it to the dealer a couple times, and they cannot find anything wrong. Do you have any ideas as to what could be causing this?
A: Your 5.4-liter V-8 uses electronic throttle control. Instead of a cable routed from the gas pedal to the throttle body, the accelerator pedal position sensor (APP) sends a signal to the powertrain control module (PCM), which then commands an electric motor in the throttle body to open the throttle plate accordingly, and off you go. This is a touchy subject with all manufacturers following the "unintended acceleration" nightmare Toyota experienced a few years back. But during all the media coverage, there was never any conclusive evidence of an electronic fault of any kind. The APP sensor has a failsafe. It sends two individual pedal position signals to the PCM. If the two signals differ in any way, shape, or form, the system shuts down and sets a diagnostic trouble code. Newer throttle control systems have an added failsafe that shuts down the throttle when the brake is applied. So no more power-braking to spin the wheels.
| Toy Tow
Your description of rpm going up when coming to a stop resembles the actual problem that got the ball rolling with Toyota. The gas pedal was getting hung up on the floormat so the gas pedal could not return fully to the idle position when you let off the gas -- not that the engine ever accelerated by itself. Crouch down and take a careful look at everything near the accelerator pedal. If you have an aftermarket floormat, or a piece of trim or anything else that looks out of place, fix it or remove it. If you still feel there's a real problem causing an unsafe condition, get it back to the dealership and press the issue. Anything is possible, but an unintended acceleration issue on these systems is more than unlikely.
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