Crazy Accelerator - help!


#1

My car: Hyundai Tiburon 2006 GT Automatic - 72,000 miles

This problem started 5/7. I was at a stoplight and my foot was on the brake. All of the sudden (while still on the brake) my car wanted to accelerate. Then all of the sudden the car shut off. I had to turn the ignition to off and then turn it back on and it started just fine.

I didn’t have any other problems until last week (6/2) and the past several days - at least once day - my car will be driving fine and then the accelerator will feel like it wants to go by itself. Then I brake and it feels like it still wants to accelerate. It also kind of sputters every so often.

I took it to a mechanic and he checked the throttle and there is nothing wrong with the throttle. So he disconnected the cruise control - thinking maybe it was switching on by itself. Nope, it has done the acceleration thing even with the disconnection.

I should add that I have had my check engine light on - it goes on and off every so often. Sometimes I can go for months without it coming on then other times it comes on all the time. I have had the codes checked and this is what the codes are showing: PO130 - O2 Sensor B1 S1 --however, I had that replaced and that code is still coming on!! And the other code is: PO118 - ENG Collant Temp Sensor Circuit High

I am at a loss??? What is the problem??? Why is my car accelerating by itself??? Can anyone help me figure out what is wrong??

Thanks!


#2

So, did you change the temp sensor?
If the temp sensor is telling the ECU that the engine is running cold, it’ll ramp up the idle.

You’re probably dealing with a defective Idle Air Control system, but my philosophy has always been that if you know you have a particular problem, such as the temp sensor, fix that first and see what happens.


#3

Mountainbike has given excellent advice, as usual.
First things first, so begin by attending to the known issue of the coolant temp sensor and hopefully that will resolve the issue.

However, the symptoms could also be the result of a defective IAC, so that is also a possibility.
In any event, the OP needs to get this attended to immediately before he causes an accident.


#4

I agree with the others. Fix the known problems and check the IAC. Until you do this, you should probably shift into Neutral at stop lights.


#5

Thank you for your advice! I am trying to resolve the problem as quickly as possible - I work a full time job so it’s kind of hard to take it anywhere. I have to take it after work. I took it to the mechanic yesterday and that’s when he couldn’t find anything wrong with the throttle, so he was at a loss at what was wrong. I will probably take it to a place this Wednesday. I can’t tonight…I have to be somewhere after work.

(I’m a she, by the way :slight_smile: )


#6

Is this mechanic someone with whom you have a long relationship and trust?
I’m puzzled as to why he/she was puzzled.


#7

The mechanic is my sister’s boyfriend. He was in kind of a rush. I also don’t understand why he is not sure about the problem. He thought it was a throttle issue.

I spoke with Firestone and they need me to leave my car there for a day…which is hard to do with work. So I probably won’t be able to until Saturday…

My boyfriend told me to shift to neutral also. I will have to start doing that. But the thing is that it doesn’t do it every time.


#8

It actually is a “throttle” issue in a very real sense. Something is causing the throttle to open and allow the engine to race. The question becomes “what?”.

The IAC system modulates the throttle at idle. It is driven by an IAC motor controlled by the car’s computer, the ECU. The ECU performs this idle control based on inputs from a “throttle position sensor” that tells the ECU how much throttle you’ve applied with the pedal, the temperature of the engine as measured by the engine temp sensor (often referred to as the “Coolant Temp Sensor” or CTS), the amount of air being drawn in by the cylinders, and some other sensor signals that tell it how fast the crankshaft is turning and some other stuff.

The temp sensor being a key ingredient here, and its having stored a fault code, leads me to it being the most likely cause.

Your sister’s BF, is he a mechanic?


#9

"Your sister’s BF, is he a mechanic?"

Good question!
For that matter, is the OP sure that this Firestone location has qualified mechanics?

I strongly advise against going to any chain-run operations like Firestone, Pep Boys, Sears, Midas, Meineke, Monro, or–God forbid–AAMCO, because the best mechanics are rarely found at those places.

I would recommend that the OP ask her work colleagues for the name of an honest, reliable independent mechanic whose shop is close to her work location.


#10

Yes, he is a certified mechanic.

I’ve called places that were recommended as good mechanics but they are not very nice on the phone and everybody needs me to leave the car for the day. I might just take off work friday and leave it somewhere thursday night. I just want it fixed.


#11

Thank you for the throttle overview! It makes sense now. As you can probably tell, I know nothing about mechanics or my car.


#12

Doesn’t this car use an electronic throttle? This could be very dangerous, you may need to take it to a dealership. It may have a recall on it and you may get it fixed for free. Check it out.


#13

I actually did take it in last year for a recall and it was fixed for free - BUT this might be something new…I did file a complaint with NHTSA.

This is the recall:

Report Receipt Date: APR 01, 2013
NHTSA Campaign Number: 13V113000
Component(s): EXTERIOR LIGHTING , SERVICE BRAKES, HYDRAULIC
All Products Associated with this Recall expand

Manufacturer: Hyundai Motor Company
SUMMARY:
Hyundai Motor Company (Hyundai) is recalling certain model year 2006-2009 Accent, model year 2007-2011 Azera, Sonata and Sante Fe, model year 2006-2007 and 2009-2011 Tucson and Elantra Touring, model year 2007-2010 Elantra, model year 2008-2011 Veracruz, model year 2009-2010 Genesis, model year 2010-2011 Genesis Coupe, model year 2007-2008 Entourage, and model year 2006-2008 Tiburon vehicles. Originally, in April 2013, Hyundai recalled 1,059,824 model year 2007-2009 Accent and Tucson, model year 2007-2010 Elantra, model year 2007-2011 Santa Fe, model year 2008-2009 Veracruz, model year 2010-2011 Genesis Coupe, and model year 2011 Sonata vehicles. In September 2013, Hyundai informed the agency that it was adding more vehicles to this campaign, representing an additional 652,512 units. The total number of vehicles being recalled is now 1,712,336. In the affected vehicles, the stop lamp switch may malfunction. A malfunctioning stop lamp switch may cause the brake lights to not illuminate when the brake pedal is depressed or may cause an inability to deactivate the cruise control by depressing the brake pedal. Additionally, a malfunctioning stop lamp switch may also result in intermittent operation of the push-button start feature, affect the operation of the brake-transmission shift interlock feature, preventing the shifter from being moved out of the PARK position and cause the Electronic Stability Control (ESC) malfunction light to illuminate.
CONSEQUENCE:
Failure to illuminate the stop lamps during braking or inability to disengage the cruise control could increase the risk of a crash. Additionally, when the ignition is in the ‘ON’ position, the transmission shifter may be able to be moved out of Park without first applying the brake. This may lead to unintentional movement of the car which may increase the risk of a crash.


#14

This is a different problem. Don’t you have a 10 year, 100,000 mile warrantee?


#15

I don’t know. I thought my warranty expired. It might have been a 5 year warranty. I will have to check.


#16

I just found out my car does have the 10 year/100,000 mile warranty.
I’m not sure what it covers because it is limited.


#17

Good point from Keith. The 5 year/60,000 mile bumper to bumper warranty would have covered this for sure. I wonder if the 10 year/100,000 mile powertrain warranty will cover it.

  • 1 for Mountainbike & checking the engine coolant temp sensor. Sounds like that’s the problem.

#18

You should have a 10 year drive train warranty. Anything that makes your car move, like engine and transmission, should be covered. Get the warranty book out of your glove box and see what it says. If there is not a separate book, this information is probably in your owner’s manual. It is still possible that this may be covered by Hyundai.


#19

Good advice from everyone. But remember, if the engine ever starts pushing you faster than you want to go, you can slip the car into neutral. If it’s an automatic it will slide to neutral (N) very easily, and I suggest you try it while driving down a quiet street. Don’t turn off the engine until you have stopped in a safe place. You need it for power steering and power brakes. The engine might roar and sound like it’s going to explode, but it will not explode. First things first, and you come first here.


#20

Thank you all!

I checked on the warranty with the dealership and they said I would have to pay diagnostics no matter what ($139) and that it is limited and the warranty might not even cover what needs to be fixed. They were giving me the runaround, probably because I’m female.

I’ve been paying more attention to the rpms and they are a little crazy all over the place and my engine revs before it does it does the acceleration thing. It never goes below 1 rpm anymore…not sure if that is normal. It usually stays around 2, then sometimes shoots to 3. I have been making sure I use neutral if it feels like it’s going to accelerate on its own.

My boyfriend has been driving my car so he can see for himself what it is doing and of course it doesn’t do it when he is driving. He is checking on the sensor at work today - he gets discounts. He is also going to see if he can replace it himself. If not, then I will have to take it somewhere.

I will let you know if the sensor replacement fixes it.