Unresponsive Throttle

dkory22 · May 30, 2010

Hello,

I'm new to the forum and hoping someone may be able to help me with a problem I've been having with my Mustang. I've had it into the dealer once and they were unsuccessful in fixing the problem. It's a stock 09 GT (picked up in Aug. 08) that only has about 27,800 miles on it. Up until now it's been a very reliable car...

A few days ago the car started stalling while driving. First two times were on the freeway then twice on side streets. More specifically, the engine continues to run, radio stays on, AC continues to run, but the throttle stops responding and the car rolls to a stop. I can mash the gas pedal and nothing happens. This happens whether the AC and radio are on or off and has only happened as I was applying more pressure to the gas pedal. I just received the car back from the service center and they replaced the throttle position sensor which did not solve the problem. Anyone have any ideas on what might be causing this?

Thanks for your help!

COBESGT · May 30, 2010

I would be taking it back to the Service Center and tell them it's not fixed and you're not paying for the Throttle Position Sensor. It sounds like you're having a problem with the communication between the foot pedal and the throttle.

I don't know this specific system, but this is how I believe this system works:
Since this is an electronic throttle there are several components to this system.

Switch on the foot pedal (input)
Motor at the throttle (end result, drives the throttle position)
Sensor at the throttle (TPS) (like big brother, watching to make sure everything is functioning properly, SAFETY DEVICE)
Controller (converts input to output, receives/sends out information)
CAN Network (where communication between everything happens)

First of all I would think this status would drive a CE Light and a DTC. It wouldn't be an ACTIVE CODE but is probably a STORED CODE. I would check to see if there are any codes present as these will help narrow down what is going on. If there aren't, I would look at all the connections at the throttle, at the foot pedal, at the computer, and then I would check into the switch at the foot pedal. My thinking is the Foot Pedal Switch is the input to the system, so if it malfunctions (not sending a signal) the system may simply think that you're not pushing the gas pedal. Hopefully this makes some sense........

dkory22 · May 30, 2010

Thanks for your response!

No, the check engine light has not come on. I should also add that all the gauges are reading normal, however I did notice something else that might be helpful. Immediately after the throttle becomes unresponsive I shut off the car and tried to turn it back on. The ignition cranked but the engine didn't immediately turn over. On the second or third attempt it usually does.

I assume these codes are something that Auto Zone could check for? I may try taking it there before the dealer on Tuesday morning.

Thanks again!

COBESGT · May 30, 2010

dkory22 said:
Thanks for your response!

No, the check engine light has not come on. I should also add that all the gauges are reading normal, however I did notice something else that might be helpful. Immediately after the throttle becomes unresponsive I shut off the car and tried to turn it back on. The ignition cranked but the engine didn't immediately turn over. On the second or third attempt it usually does.

I assume these codes are something that Auto Zone could check for? I may try taking it there before the dealer on Tuesday morning.

Thanks again!

Humm, sounds like maybe a crank or cam position sensor issue. However this should create a DTC. Long cranking usually indicates a problem with one of them, because it takes more rotations for the computer to figure out where everything is. I think these cars have two methods to knowing exactly where the engine is at while running or even cranking, the Crank Position Sensor and the Cam Position Sensor. In most situations the crank position sensor is the primary sensor and the cam position sensor is secondary and acts as a backup. In a lot is situations, the car may still run with the cam position sensor bad but if the crank position sensor is bad, it won't run at all. On our cars one thing that I don't know for sure is what happens if the cam sensor is bad, it may not allow you to rev the engine, because of the variable cam timing (this may be a failsafe mode).
Regardless of all of this possibly usless information, you should be able to take your car to AutoZone and they can check for codes.

dkory22 · May 30, 2010

Well, at least that makes me feel like I won't get stuck somewhere, although it is still dangerous to drive. Thanks again for your help, I'm far better armed to get to the bottom of the problem now.

Casey4s · May 30, 2010

COBESGT said:
I would be taking it back to the Service Center and tell them it's not fixed and you're not paying for the Throttle Position Sensor. It sounds like you're having a problem with the communication between the foot pedal and the throttle.

I don't know this specific system, but this is how I believe this system works:
Since this is an electronic throttle there are several components to this system.

Switch on the foot pedal (input)

Motor at the throttle (end result, drives the throttle position)

Sensor at the throttle (TPS) (like big brother, watching to make sure everything is functioning properly, SAFETY DEVICE)

Controller (converts input to output, receives/sends out information)

CAN Network (where communication between everything happens)

First of all I would think this status would drive a CE Light and a DTC. It wouldn't be an ACTIVE CODE but is probably a STORED CODE. I would check to see if there are any codes present as these will help narrow down what is going on. If there aren't, I would look at all the connections at the throttle, at the foot pedal, at the computer, and then I would check into the switch at the foot pedal. My thinking is the Foot Pedal Switch is the input to the system, so if it malfunctions (not sending a signal) the system may simply think that you're not pushing the gas pedal. Hopefully this makes some sense........

I had one go bad on my car in less than a year. I had some bolt ons on my car so the dealer refused warranty and made me buy a whole new throttle body because you can't buy just that motor assembly. (At least not then )

dkory22 · May 30, 2010

Casey4s said:
I had one go bad on my car in less than a year. I had some bolt ons on my car so the dealer refused warranty and made me buy a whole new throttle body because you can't buy just that motor assembly. (At least not then )

Thanks for the response. Were the symptoms the same as the ones I'm experiencing?

Casey4s · May 30, 2010

dkory22 said:
Thanks for the response. Were the symptoms the same as the ones I'm experiencing?

The car would start but it was like the gas pedal was not connected. It only did it once but it never recovered again, where as your seems to be intermiten.

Big Large · May 30, 2010

my buddy is a mechanic at a ford dealer. they have issues with the throttle bodies on these cars. have it checked out. i think it is a 2106 code if the dealer scans the car. could be wrong on that number though

dkory22 · May 31, 2010

Thanks, I'm actually not sure if the dealer even checked for trouble codes the first time around. I'll make sure they do this time and fully check out the throttle assembly.

COBESGT · May 31, 2010

dkory22 said:
Thanks, I'm actually not sure if the dealer even checked for trouble codes the first time around. I'll make sure they do this time and fully check out the throttle assembly.

If the Dealer didn't look for DTC's, then shame on them. That's the easiest thing that you can do to help diagnose a problem.

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