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Discussion Starter · #1 ·
After all the publicity Toyota has been receiving lately, this is going to be hard to believe, but my Forte EX accelerated by itself last week. I was driving from Johnson City, TN to Asheville, NC. This is a mountainous area, and I was using the cruise control on the interstate. I had the cruise set for about 65 mph. As I was going downhill, the car overran the cruise just a little. As I started back up the next hill and the car slowed to 65, the cruise kicked in just as it should, but this time it continued to accelerate, going uphill, until it reached almost 75 mph. At that point, it started easing up, and I gradually slowed back down to the set speed.

There wasn't much traffic on the road, and I wasn't in any danger, so I just let it do it's thing to see what would happen. I could have shifted into neutral or turned off the car at any time if neccessary, so I didnt' panic. But it was a bit disconcerting.

Does anyone have any suggestions on what could have caused this, or what I should do about it?

Thanks, Ron
 

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Hey Ron! I did a similar drive from nashville to ashville a few years ago and I totally know the roads you are talking about, they were so much fun! Did you pass through that beautiful valley town in Virginia?

Anyway, I believe the manual says to not use cruise on hills for that very reason, and even on my drive, my rental ford 'exploder' behaved he same. Crusie computers ate not designed for hills.

I would like to say that I believe you aren't experiencing the Toyota phenomena.
 

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Discussion Starter · #3 ·
D113,
Thanks for the reply. I don't think I'm having the Toyota problem either, but I disagree that cruise control is not meant for hills. I live in Johnson City, TN and I drive on hills every day. I have cruise in every car I drive, and none of them do this. Cruise contol is designed to sense the vehicle speed, and adjust the throttle to match the set speed. In this case it kept accelerating beyond the set speed.
 

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I undestamd what you are saying but I've had thus happen on a ford explorer and a cavalier. I think it all relates to gear ratios too. If it's having trouble in 4th it will drop to third and really rev until it feels that it doesn't need third to overcome the hill. There's also BIG difference in the ashville trip's hills as they are actually mountains and not simple rolling hills. I'm not trying to argue but doesn't the manual warn of these conditions? I too have used cc on rolling hills but on mountain like ones you will have sporadic results too depending in engine size and vehicle weight.
 

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You might want to call your dealer on this......... I know that for my first oil change they ask me some question about cruise and they reprograme something in order to have the cruise control work flawlessly!! Not a recall but.........
 

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Discussion Starter · #6 ·
I undestamd what you are saying but I've had thus happen on a ford explorer and a cavalier. I think it all relates to gear ratios too. If it's having trouble in 4th it will drop to third and really rev until it feels that it doesn't need third to overcome the hill. There's also BIG difference in the ashville trip's hills as they are actually mountains and not simple rolling hills. I'm not trying to argue but doesn't the manual warn of these conditions? I too have used cc on rolling hills but on mountain like ones you will have sporadic results too depending in engine size and vehicle weight.
Thanks again. I have had the experience of the car downshifting in order to overcome the hill, but that won't make it exceed the set speed. I think I'll tell the dealer about it, as suggested by another poster. Maybe there's some electronic adjustment.
 

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What you are describing is normal for cruise control, a similar type of situation happened to me on my 03 Chevy Tahoe... I would never use it on a hill just because it will waste more gas trying to reach the set speed... kinda scary when it accelerates lol, but that's what it was designed to do.
 

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Not an adjustment, exactly. There is a cruise control reprogram available for inconsistent speeds which may help in this case. However I will also agree with D113, your actual topography may also have some influence that the computer will struggle with.

One of the biggest drawbacks of the electronic throttle is simply that it must 'guess' at so many things, as it cannot see out the window. Sometimes... it guesses wrong.
 

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After all the publicity Toyota has been receiving lately, this is going to be hard to believe, but my Forte EX accelerated by itself last week. I was driving from Johnson City, TN to Asheville, NC. This is a mountainous area, and I was using the cruise control on the interstate. I had the cruise set for about 65 mph. As I was going downhill, the car overran the cruise just a little. As I started back up the next hill and the car slowed to 65, the cruise kicked in just as it should, but this time it continued to accelerate, going uphill, until it reached almost 75 mph. At that point, it started easing up, and I gradually slowed back down to the set speed.

There wasn't much traffic on the road, and I wasn't in any danger, so I just let it do it's thing to see what would happen. I could have shifted into neutral or turned off the car at any time if neccessary, so I didnt' panic. But it was a bit disconcerting.

Does anyone have any suggestions on what could have caused this, or what I should do about it?

Thanks, Ron
thats cruise control on a hill in any car
 

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Discussion Starter · #10 ·
Cruise control acceleration

Not an adjustment, exactly. There is a cruise control reprogram available for inconsistent speeds which may help in this case. However I will also agree with D113, your actual topography may also have some influence that the computer will struggle with.

One of the biggest drawbacks of the electronic throttle is simply that it must 'guess' at so many things, as it cannot see out the window. Sometimes... it guesses wrong.
Thanks for all your responses. Several of you said that this is normal for cruise control on a hill. No, it is not. I've driven cars with cruise for over 35 years. They will sometimes go too fast downhill, and sometimes not keep up going uphill. This car accelerated 10mph past the set speed while going uphill. As for the electronic throttle having to 'guess' at so many things, that's not true either. The computer gets an exact signal from the Vehicle Speed Sensor. I is supposed to 'know' how fast the car is going, and adjust the throttle accordingly.

The good advice I got was to let the dealer know what happened, and to ask if there is a cruise control 'reprogram' available. I will follow that advice. Thank you all again.:)
 

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Wow, this thread seems really really strange to me. I've never had that problem on any car I've ever driven. I'm currently leasing a 2010 Explorer and the cruise keeps it to exactly the speed, except going down a hill when it will sometimes pick up a couple mph.

My last car was an old 1992 STS, it was also just fine, although going up a hill it would slam the gas to the floor, downshift, and accelerate like mad... but it didn't ever go over where it was set.

Maybe because I am in Southern California and there really aren't hills like in other parts of the country? I don't know, I can remember as far back as 1979 when I had a 1975 Sedan de Ville in Florida and drove all over the South, and that cruise control was also just fine, it accelerated like mad up a hill but never overshot the mph.

*confused*
 

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Straight out of the Service Action:


Subject (SA094) ECM Upgrade- Auto Cruise Speed Improvement Condition Some Forte (TD), & Forte Coupe (TD) vehicles may experience the following symptoms/conditions:
  • Cruise control (Speed variation during a constant speed on an uphill road)
  • RPM Drop delay while shifting of the gears. (only 2.0 Manual Transmissions)
 

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Discussion Starter · #13 ·
Straight out of the Service Action:



Subject (SA094) ECM Upgrade- Auto Cruise Speed Improvement Condition Some Forte (TD), & Forte Coupe (TD) vehicles may experience the following symptoms/conditions:
  • Cruise control (Speed variation during a constant speed on an uphill road)
  • RPM Drop delay while shifting of the gears. (only 2.0 Manual Transmissions)
Thanks. I did not find the Service Action you referenced above, but I found this at kiatechinfo.com:

KMA is conducting a Service Action SA013 in relation to some early 2010 MY Forte / Koup models which were produced from Feb. 24, 2009 to Aug. 19, 2009. The action will involve a reprogram of the cruise control logic to provide an improvement developed by KMC for uphill driving and to ensure that all Fortes are operating with the same logic. KMA does not believe that customers will be aware of any change in vehicle operation.
 

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Yup, same date range and description, so same programming. US and Canada use different numbering, apparently... no biggy. If your build date is in that range, it will likely help.
 
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