Enging revving/racing on its own

  • 4 CYL
  • AWD
  • 40,000 MILES

We recently bought a 2012 Hyundai Tucson that was a lease return. I noticed that, after driving for several miles, and usually only at steady speeds above 40 mph (neither accelerating nor decelerating), the car engine revs up on its own, quite loudly and noticeably with a "racing" sound. This only lasts a few seconds and then goes back to normal. It's difficult to tell since it happens so quickly, but it seems as though the vehicle speeds up slightly when this happens. I know my heart does!

We took it in to the dealer. No code is thrown when it does this so they were not able to detect anything. I think both husband and techs thought I was imagining things.

After happening multiple times in one trip, I brought it back a few weeks later and one of the techs took the car home for a week. Quick trips through town didn't cause the unintended revving for him; however, a trip out of town on the highway did, several times. Still, no code was thrown.

They have contacted Hyundai corporate but have yet to hear back (a month now). We have not been driving it in that time since.

I have read that there is sometimes a problem with the throttle position sensor on all models of Hyundai, which causes varying degrees of unintended acceleration. We asked about this but were told it couldn't be. I have not pressed the issue, but they won't replace the throttle position sensor without a code since the car is under warranty. Feeling the situation is unsafe, I'd prefer to pay the money for the part and pay for the labor just to be sure but have not brought this up yet. The dealership's only suggestion is that it could be the transmission, but they don't know how/why without codes and so can't fix anything.

Now the dealership is suggesting we drive it until it throws a code (but why would it if it hasn't yet?) Or if a dash light comes on (so far, no dash light). My husband will be doing this next week, but if no dash light happens and no code is thrown, what then? Drive it until it drives us off a cliff?

Other ideas would be appreciated. Thanks!
Do you
have the same problem?
Tuesday, January 13th, 2015 AT 11:18 PM

1 Reply

The problem you described could be a few things. However, each should have set a code. This may sound too simple, but has anyone checked the throttle plate to make sure there is no excessive carbon build up causing the throttle to close slowly? Also, has the engine been checked for vacuum leaks or has the idle air control valve been checked to see if it may be responding incorrectly? The thing is, if a component is still sending a signal to the car's computer, even if it is wrong, the computer will think it's working. Thus, there is no check engine light coming on.

As far as the throttle position sensor, I question that is the problem too, and I'm not sure why they feel the transmission is the issue. That doesn't stand to reason for me.

Regardless, since you have been waiting this long, I recommend contacting the Zone Representative for assistance. Let the person know you have been waiting, feel the problem is a safety issue, and don't feel it is smart to wait till it breaks to determine where the problem is originating. Here are the numbers, addresses. For Hyundai's National and Zone offices. I would contact them and request assistance on this issue.

National Office:
Hyundai Motor America
P.O. Box 20850
Fountain Valley, CA 92728-0850
(Mon - Fri, 5:00 am - 6:00 pm PST)
By Email: consumeraffairs@hmausa. Com

Zone Office:
Central Regional Office
Consumer Affairs Department
700 N. Enterprise Street
Aurora, IL 60504
(630) 907-4700

Let me know what they tell you.

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Wednesday, January 14th, 2015 AT 5:16 AM

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