Sudden and unexpected acceleration on Blue Cruise

melissphillips

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So I just took my MachE in for the recalls that were on it and when it was there, they did all the software updates and I now have Blue Cruise. On the way home, I turned on the Adaptive Cruise Control like normal, and it went into hands-free mode as expected, then went back into hands-on mode when on a ramp as expected. But when I got to the bottom of that ramp which lead to a 4-lane highway again, suddenly my speed went from 58 to 85 on the cruise control. I thought it was me and I'd done something wrong. So I turned it off and went home to watch a few videos to learn more.

Later this evening I took it back out again and found that it pretty reliable does the same thing time and time again, sometimes to 75, sometimes to 85 but it happens when the road opens up from 3 lanes to 4 or after a ramp has come into the highway. I turned on my phone and was able to reliable catch it on video. Now when this happened right as a car was also merging in front of me I noticed that although the target speed had jumped to 85 the adaptive cruise control was holding the speed at a lower speed in order to maintain the proper distance between cars, so at least there is that. But as soon as that car would have changed lanes I would have zoomed right up to 85 - which by the way, the car also knew I was in a 65 MPH zone.

After a few miles and a few exits where I had watched it happen repeatedly (and videoed it happening), I decided to head back home, exited the highway and when I tapped the breaks, of course, the adaptive cruise control went into inactive with the 55 I had been going showing with a strikethrough. I sat at the light waiting to go back in the other direction and right as the light turned green to turn back on the on ramp I noticed the number under the strikethrough had gone up to 75. While I was sitting still.

I turned the cruise control off and on and that reset it to the current speed, I tapped my breaks to inactivate it and watched the speed that was struck through and sure enough, it went up and down as I was driving, going between 75 and 85 even though I wasn't actively using the cruise control the target speed was changing.

The only time the target speed seems to static is when I'm in Hand On mode.

This is basically rendered the cruise control unsafe and unusable in my car. Has anyone else experienced this?
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JohnnyForensic

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Or instead of turning off speed sign recognition, check to see what the tolerance value is set to. It sounds like you might have it set to 20 over the limit, which is the maximum setting if I remember correctly. It’s under the adaptive cruise control settings.
 

SnBGC

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The speed limit recognition threw me off too. Apparently it gets turned on as a consequence of the BC software install.
 

Mach-Lee

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You have speed sign recognition set to +20 MPH. It takes off when it sees a speed limit sign. Go into your settings and change it to +5 or whatever you drive at. Or turn it off if it bugs you.

I bet the dealer techs were playing with that.
 


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melissphillips

melissphillips

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Okay thanks guys - best forum ever! Yes, I don't know if that was there before and just set to 0 or if it's new and the default is set to max or maybe the techs played with it but thank goodness - yes it was set to the maximum tolerance. I thought the car was all kinds of jacked up and crazy.
 

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I have a +5 tolerance set and turned off my speed sign recognition. Turned on BC on country road with probably 40-45 speed limit. It accelerated from driving speed very quickly so I tapped brake and looked at the display… 70 was its goal. I have no idea where that came from. It usually sets to mph at time of engaging BC (would have been 40ish). Has not been in for any service and now that all my OTA notifications are gone from my messages, I don’t know what I’ve received.
 

MellowJohnny

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Happened to me today as well, which is odd because I turned off Speed Sign Recognition months ago. So it seems some update in the last while (I'm on 4.1.3) must have reset it?

I'm guessing it was perhaps 4.1.2 since there were a lot of moving parts in that one :)
 

azerik

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Mine is seemingly reverting to whatever it was set to previously. Like key off doesn’t reset it. I was on a huge ramp with terrible expansion joints. Bumped the cruise and it took off. With the sway bars and skinny tires I came real close to it customizing the right side of the car in concrete grey. No sign to be seen. I’m on 4.1.3 now
 

azerik

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Stumbled upon a different issue on the Lightning forum. If not holding the brake when keying off the trip meters randomly don’t reset. I’m wondering if this is the case as I’ve been 1pd and key off while hitting the parking brake.
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