Hyundai Repair: engine raced over 100mph, hyundai elentra, hyundai corp

Question
I have a 2006 Hyundai Elentra,51000 thousand miles,still under warrenty. I drove my wife to work in the morning and was in the parking space just ready to put it in park and all of a sudden the throttle started racing over 100mph.The car started to go over the concreate curb and was ready to go through the front building where my wife works.I stepped harder on the brake and threw it into park and shut it off. My car was towed to the dealer tuesday morning,they kept it there for two days before looking at it. they called me thursday and said they checked inside and out and can't find nothing wrong. my wife and i refuse to drive the car because it's a danger to be on the road waiting for it to happen again,our live's and others are more value. I called Hyundai Corp.Office and they are sending a field inspector to the dealership to investegate deeper into the car. For that being said,I had a 2003 elentra seven years ago brand new. Two days later with my wife and granddaughter in the car,waiting in a parking lot for traffic to go by on the main road, with my foot on the brake the car throttle started to race and took us right in traffic,cutting of car's,angry drivers at me not knowing what's going on.no one was hurt. The dealer at that time found a sencer in the computer box that controled the throttle was defected. I need a answer on this on my car,I feel it's the sencer but they said no.                               thank you

Answer
Hi, Jim.  I'm not sure I completely understand what was occurring.  

When you say over 100MPH, are you referring to the rpm display on the tachometer or the actual speed of the vehicle?  The reason I ask this is that I'd think it would be impossible for the vehicle to reach 100MPH without leaving the parking spot, even if you were purposely accelerating as fast as you could.  If you're referring to the tachometer RPM gauge, can you indicate the number on display closest to the needle?  For example, if the needle were on 2, that would indicate 2000 RPM.

It would also seem that you received an incorrect explanation of the problem with your 2003 Elantra or that you misunderstood the explanation you were given.  Presuming the term "computer box" to mean the engine control module (ECM) that governs the fuel management system, there are no sensors inside this computer, and this computer does not control the throttle.

The throttle regulates the amount of air which can enter the engine.  On both the 2003 and 2006 Elantra, the throttle opening is regulated via a lever on the throttle body, which is in turn controlled by a cable going to the accelerator pedal inside the car.  Any one of a number of problems can cause the throttle to stick open: the throttle plate shaft can stick in the throttle body, the throttle return spring can fail, the cable can bind or stick, or something may cause the accelerator pedal to be stuck down.  In the case of the spring, it would be permanently broken, and in the cases of the binding cable or shaft, I would expect that the problem would remain until the throttle was closed or the item was freed.  More importantly, none of these problems can cause the throttle to open on its own.  

The cruise control has the capability of opening the throttle, but for this to occur while the vehicle is at a stop, there would need to be multiple failures.  I.e., it would need to think the vehicle were already moving at a speed of about 30MPH or more, *and* if your foot were on the brake (as I would expect at a stop), there would need to be a short in the brake switch circuit, either in the wiring or in the switch itself.

For these reasons, I suspect the throttle did not actually open.  It is possible, however, for the engine speed to change by the ECM delivering more fuel.  This could be caused by any number of failures, but without the additional air provided by the opening of the throttle, it would be impossible for the engine to run very fast.  While it might go well above normal idle, this should be easily overpowered by applying the brakes a little harder.

The fact that Hyundai is sending a field engineer shows that they're taking your complaint seriously.  The field engineer is interested in finding actual problems for a number of reasons.  Hyundai not only doesn't want to have you or your family injured, but they also want to make sure they appropriately address any issues which could put a large group of people in danger.

If you feel that Hyundai has not satisfactorily investigated your issue, I encourage you to contact the National Highway Traffic Safety Administration, as these are the types of problems they investigate.

Lastly, if you do not have your faith restored in this car, my best advice is to sell it and get another car of your choice.  Otherwise, you'll be left with a car you feel you cannot drive.