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Discussion Starter #1 (Edited)
This is getting worse, to the point I am afraid to drive my car. While driving I can feel the car slowly accelerating, feels like it has more power. I will go to stop and press the brake, car will stop but engine will run at full speed. I have to shift it in to park and take my feet off all pedals, then it returns to normal. I have had several very close calls so it’s only a matter of time before it causes an accident. I have had it in the shop twice and they say they can not find anything wrong. A friend suggested it could be a faulty throttle position switch? Anyone have any idea or what I could tell the dealer to look for?
 

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First, make certain you have your foot on the brake, not the accelerator. Know it sounds odd, but with the Jeeps, Audi etc, people would floor the accelerator thinking they are on the brake pedal. In drive, put and press your foot on the brake pedal with you left foot, press the accelerator with your right foot, car won't move, gas won't overcome the brakes.

Also, maybe you meant you put the car in neutral, but if it were to put it in park when driving, if it would go in, it would rip the trans apart.
 

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This is getting worse, to the point I am afraid to drive my car. While driving I can feel the car slowly accelerating, feels like it has more power. I will go to stop and press the brake and the car will accelerate at full speed to the extent that I can’t stop it from moving forward by just using the break. I have to shift it in to park and take my feet off all pedals, then it returns to normal. I have had several very close calls so it’s only a matter of time before it causes an accident. I have had it in the shop twice and they say they can not find anything wrong. A friend suggested it could be a faulty throttle position switch? Anyone have any idea or what I could tell the dealer to look for?
You may simply just need new rotors and pads. If your rotors are thinner than minimum thickness and pads are somewhat worn, they are not going to stop you in a reasonable time especially if they are really hot or you're driving fast.
 

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Discussion Starter #4
First, make certain you have your foot on the brake, not the accelerator. Know it sounds odd, but with the Jeeps, Audi etc, people would floor the accelerator thinking they are on the brake pedal. In drive, put and press your foot on the brake pedal with you left foot, press the accelerator with your right foot, car won't move, gas won't overcome the brakes.

Also, maybe you meant you put the car in neutral, but if it were to put it in park when driving, if it would go in, it would rip the trans apart.
I know what I said, and it is exactly what I did. I also did not have my foot on the gas instead of the break or I would have killed the people in front of me.
 

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Discussion Starter #5
You may simply just need new rotors and pads. If your rotors are thinner than minimum thickness and pads are somewhat worn, they are not going to stop you in a reasonable time especially if they are really hot or you're driving fast.
?? How would Rotors and pads make the car accelerate out of control? Brakes where fully serviced less then 3 months ago when the entire car was serviced.
 

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Discussion Starter #6
Let me explain this again as apparently I was not clear enough. Driving normally, light turns red so I apply the breaks. Engine races as if the accelerator was being depressed all the way down. Car does not continue moving forward because I have the break peddle fully depressed. I must keep my foot on the brake peddle fully depressed to stop the car from moving forward and hitting the vehicle in front. Only way to stop the engine from racing out of control is to put the car in to park and take my foot off of the break.
 

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Sounds like the engine races ONLY when you are applying the brake. Is that right?

Then the engine stops racing when you REMOVE your foot from the brake pedal?
 

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Hmm maybe there is a mechanical issue near the pedal mechanisms.

Can you take a photo of the brake area, like position the camera at floor level looking up at the back of the pedal area? And also the opposite, position the camera at knee level looking back and down.
 

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Discussion Starter #10
Hmm maybe there is a mechanical issue near the pedal mechanisms.

Can you take a photo of the brake area, like position the camera at floor level looking up at the back of the pedal area? And also the opposite, position the camera at knee level looking back and down.
It's not a mechanical issue, that I know for sure. When it happens it starts gradually, the car will start to rev higher about 5 minutes before it goes nuts. It builds up, then when I stop it goes all out. The car has been checked twice by the dealer and they keep saying the issue can't be reproduced so there is nothing they can do. It only happens maybe once a month, but that is still far to often.
 

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Discussion Starter #11
It's not a mechanical issue, that I know for sure. When it happens it starts gradually, the car will start to rev higher about 5 minutes before it goes nuts. It builds up, then when I stop it goes all out. The car has been checked twice by the dealer and they keep saying the issue can't be reproduced so there is nothing they can do. It only happens maybe once a month, but that is still far to often.
Dealer wants me to bring it in tomorrow morning again, but this time they said not to drive it have it towed so maybe they know something this time. I will update if they figure it out.
 

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This is getting worse, to the point I am afraid to drive my car. While driving I can feel the car slowly accelerating, feels like it has more power. I will go to stop and press the brake and the car will accelerate at full speed to the extent that I can’t stop it from moving forward by just using the break. I have to shift it in to park and take my feet off all pedals, then it returns to normal. I have had several very close calls so it’s only a matter of time before it causes an accident. I have had it in the shop twice and they say they can not find anything wrong. A friend suggested it could be a faulty throttle position switch? Anyone have any idea or what I could tell the dealer to look for?
First, I wouldn't put the gearshift in "Park" while moving - nothing good can come of this. Shift to neutral or turn off the engine if necessary. Also. a defective throttle position sensor might be the cause. Good luck on getting this fixed soon.
 

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Discussion Starter #13
First, I wouldn't put the gearshift in "Park" while moving - nothing good can come of this. Shift to neutral or turn off the engine if necessary. Also. a defective throttle position sensor might be the cause. Good luck on getting this fixed soon.
Vehicle was not moving when it was shifted in to park. Vehicle was at a stand still with break fully depressed while the engine was attempting to run at maximum speed. This has already been explained. They are already looking at the throttle switch but they have had it for some time now and still can not find the issue. Most likely outcome at this time is getting rid of the vehicle.
 

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Vehicle was not moving when it was shifted in to park. Vehicle was at a stand still with break fully depressed while the engine was attempting to run at maximum speed. This has already been explained. They are already looking at the throttle switch but they have had it for some time now and still can not find the issue. Most likely outcome at this time is getting rid of the vehicle.
Hope your issue is fixed soon. In case this isn't fixed soon and you need to brake again, you can gently nudge it into neutral while you are braking and then go into park once you are fully stopped. Going into neutral while braking is so that you aren't fighting against the engine as you brake.

or turn off the engine if necessary
Don't turn off the engine while braking because then you lose power brakes.
 

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Discussion Starter #15
Hope your issue is fixed soon. In case this isn't fixed soon and you need to brake again, you can gently nudge it into neutral while you are braking and then go into park once you are fully stopped. Going into neutral while braking is so that you aren't fighting against the engine as you brake.



Don't turn off the engine while braking because then you lose power brakes.
If they can't find the issue, I will not be driving the car at all as currently it's a death trap. The dealer has had it since last week but still have no idea what is causing it. From searching on the net, this seems to actually be an issue with many Optimas. I have found at least 6 other people having the exact same issue. Several had it fixed by replacing the throttle switch (at $700.00+), several have had the switch replaced only to have the problem reappear in less then 6 months and some have never had it fixed. I love the my car, but if the dealer can't get this resolved I will have no choice but to get rid of it and could not justify getting another Kia at that point.
 

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Discussion Starter #16
Just got off the phone with the dealer. They can not reproduce the issue. They are going to keep it until next week and let one of the employees who commutes roughly 80 miles use it for a few days.
 

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I still cannot understand why pressing the brake pedal would cause the engine to race.

Or why removing your foot from the brake pedal would make the engine stop racing.

The only other cause I can think of is this is NOT a problem with the car, but just accidentally pressing both pedals at the same time.

If you press the brake and gas pedals together, the engine races. If you remove your foot from the brake and gas pedals, the engine stops racing.
 

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Discussion Starter #18
I still cannot understand why pressing the brake pedal would cause the engine to race.

Or why removing your foot from the brake pedal would make the engine stop racing.

The only other cause I can think of is this is NOT a problem with the car, but just accidentally pressing both pedals at the same time.

If you press the brake and gas pedals together, the engine races. If you remove your foot from the brake and gas pedals, the engine stops racing.
It's not really removing my foot from the brake that stops it, its more putting it in to park then back in to drive. And no, I am not pressing both pedals at the same time. I would need to twist my foot at a very odd angle to do that. This is also something that others are experiencing.
 

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Have you ever had the throttle body cleaned? Only way the engine can accelerate is if the throttle body butterfly does not close properly thats perceived as accelerating you let off the gas and it keeps going because the butterfly gets stuck in the bore it does not close so same as you stwepping on the gas.
I dont think its a fly by wire throttle body I am not a Kia expert. But over all the posts you made not one mentions its mileage.
it may never have had its throttle body cleaned. Yikes!
Go on you tube and look up throttle body cleaning posts so you understand how it works.
Most likely the TB butterfly is getting stuck in a gunky bore.
If its fly by wire the TB motor may be bad. Pretty common on modern cars.
 

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Discussion Starter #20
Have you ever had the throttle body cleaned? Only way the engine can accelerate is if the throttle body butterfly does not close properly thats perceived as accelerating you let off the gas and it keeps going because the butterfly gets stuck in the bore it does not close so same as you stwepping on the gas.
I dont think its a fly by wire throttle body I am not a Kia expert. But over all the posts you made not one mentions its mileage.
it may never have had its throttle body cleaned. Yikes!
Go on you tube and look up throttle body cleaning posts so you understand how it works.
Most likely the TB butterfly is getting stuck in a gunky bore.
If its fly by wire the TB motor may be bad. Pretty common on modern cars.
I will mention it to the dealer when I talk to them again. For reference, the car has a little over 46,000 on it.
 
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