WTF is wrong with my car??!!! Scary thing just happend look at below and please give me your input

Asked by May 21, 2014 at 12:02 PM about the 2001 Pontiac Grand Prix GT

Question type: Maintenance & Repair

Using cruise control in my 2001 grand Prix
coming up a mountain and it excelerated up
to 80 and rpms shot to almost 7. I turned
off cruise control  and applied the brake but
it just kept accelerating.

8 Answers

20,425

And you lived to tell about it- have your cruise control checked- most likely it strained to the max and got stuck somehow trying to maintain constant speed uphill- are you sure you stepped on the brake and not the accelerator? the brakes should slow the car down even if the engine is still pulling- BTW it is bad practice to use cruise control in the mountains- the car will speed up unnecessarily going up a steep slope, in order to maintain that set speed- (almost impossible to maintain when going up a steep grade)- adjust your driving to accept a little slowing down when going uphill and a little speeding up going down- turn the cruise off and you get there just as fast-

1 out of 1 people think this is helpful.

Not nessisarly in the mountains more like a steep hill I've driven this road a million times with cruise control and never had this happen

15,815

I agree that you should be able to use your cruise on a legally driveable road,but. you are putting a lot of faith in a bunch of electric signals that the car is trying to interpret and adjust to when you are driving on a road that is hilly. Basically all the wires and sensors are exposed to the weather on a constant daily basis and metal rusts,contacts get dirty, etc.,etc,. I am still waiting for the newest gereration of screw ups when the dam things try to park themselves as you're speeding down the hyway. Christ- my cable TV box has been know to click off and that's just because it got too dusty or too humid

4,415

The problem is unrelated to the cruise control. Check the throttle cables and return springs, as well as the throttle position sensor. Even a slightly sticky pedal return will cause the engine to accelerate, requiring a heavy brake force to slow the car. Good luck!

15,815

I can see that a stuck cable would prevent the cable from decreasing the speed (ie: prevent return) BUT I CAN'T see how it would move the cable to acceleration?

4,415

The throttle on EFI engines will hang open for many reasons, such as carbon buildup or dirt. A weak return spring will also let it open under high RPM. Since the post stated that Cruise Control was shut off and the engine continued to accelerate, the problem is mechanical as stated, or the throttle body/throttle position sensor needs to be checked. A throttle hanging at less than 10% of WOT will cause the engine to gain RPM. http://www.buzzle.com/articles/symptoms-of-a-bad-throttle-position-sensor.html

15,815

buzzle article systems do not match what Jacquie posted - no to symptoms 1 to 4 , no to symptom 5 because she was breaking not pushing on the pedal, article says valve pops open giving burst of acceleration ( doesn't mention continued acceleration ) and somehow I doubt a mechanically stuck throttle would cause continued acceleration on a hilly road. I still think Jamnblues is closer to the answer.

15,815

The DANGER of this problem is really more important than argueing over the possible causes, I don't think there is only one cause - please Google "cruise control" + "disengage" + "acceleration" - this happens a lot more often then I would have ever imagined! Law suits, injury,death and no real answers. I'm going back to my original opinion about my TV box and the dam things trying to park themselves while driving down the highway. Get this computer junk out of our cars!

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